Massive refactor and introduction of restheadspec

2025-12-31 17:28:58 +00:00 · 2025-11-06 16:15:35 +02:00
parent 399cea9335
commit 8e06736701
22 changed files with 2472 additions and 1046 deletions
--- a/pkg/restheadspec/HEADERS.md
+++ b/pkg/restheadspec/HEADERS.md
@@ -0,0 +1,614 @@
+# RestHeadSpec Headers Documentation
+
+RestHeadSpec provides a comprehensive header-based REST API where all query options are passed via HTTP headers instead of request body. This document describes all supported headers and their usage.
+
+## Overview
+
+RestHeadSpec uses HTTP headers for:
+- Field selection
+- Filtering and searching
+- Joins and relationship loading
+- Sorting and pagination
+- Advanced query features
+- Response formatting
+- Transaction control
+
+### Header Naming Convention
+
+All headers support **optional identifiers** at the end to allow multiple instances of the same header type. This is useful when you need to specify multiple related filters or options.
+
+**Examples:**
+```
+# Standard header
+x-preload: employees
+
+# Headers with identifiers (both work the same)
+x-preload-main: employees
+x-preload-secondary: department
+x-preload-1: projects
+```
+
+The system uses `strings.HasPrefix()` to match headers, so any suffix after the header name is ignored for matching purposes. This allows you to:
+- Add descriptive identifiers: `x-sort-primary`, `x-sort-fallback`
+- Add numeric identifiers: `x-fieldfilter-status-1`, `x-fieldfilter-status-2`
+- Organize related headers: `x-preload-employee-data`, `x-preload-department-info`
+
+## Header Categories
+
+### 1. Field Selection
+
+#### `x-select-fields`
+Specify which columns to include in the response.
+
+**Format:** Comma-separated list of column names
+```
+x-select-fields: id,name,email,created_at
+```
+
+#### `x-not-select-fields`
+Specify which columns to exclude from the response.
+
+**Format:** Comma-separated list of column names
+```
+x-not-select-fields: password,internal_notes
+```
+
+#### `x-clean-json`
+Remove null and empty fields from the response.
+
+**Format:** Boolean (true/false)
+```
+x-clean-json: true
+```
+
+---
+
+### 2. Filtering & Search
+
+#### `x-fieldfilter-{colname}`
+Exact match filter on a specific column.
+
+**Format:** `x-fieldfilter-{columnName}: {value}`
+```
+x-fieldfilter-status: active
+x-fieldfilter-department_id: dept123
+```
+
+#### `x-searchfilter-{colname}`
+Fuzzy search (ILIKE) on a specific column.
+
+**Format:** `x-searchfilter-{columnName}: {searchTerm}`
+```
+x-searchfilter-name: john
+x-searchfilter-description: website
+```
+This will match any records where the column contains the search term (case-insensitive).
+
+#### `x-searchop-{operator}-{colname}`
+Search with specific operators (AND logic).
+
+**Supported Operators:**
+- `contains` - Contains substring (case-insensitive)
+- `beginswith` / `startswith` - Starts with (case-insensitive)
+- `endswith` - Ends with (case-insensitive)
+- `equals` / `eq` - Exact match
+- `notequals` / `neq` / `ne` - Not equal
+- `greaterthan` / `gt` - Greater than
+- `lessthan` / `lt` - Less than
+- `greaterthanorequal` / `gte` / `ge` - Greater than or equal
+- `lessthanorequal` / `lte` / `le` - Less than or equal
+- `between` - Between two values, **exclusive** (> val1 AND < val2) - format: `value1,value2`
+- `betweeninclusive` - Between two values, **inclusive** (>= val1 AND <= val2) - format: `value1,value2`
+- `in` - In a list of values - format: `value1,value2,value3`
+- `empty` / `isnull` / `null` - Is NULL or empty string
+- `notempty` / `isnotnull` / `notnull` - Is NOT NULL and not empty string
+
+**Type-Aware Features:**
+- Text searches use case-insensitive matching (ILIKE with citext cast)
+- Numeric comparisons work with integers, floats, and decimals
+- Date/time comparisons handle timestamps correctly
+- JSON field support for structured data
+
+**Examples:**
+```
+# Text search (case-insensitive)
+x-searchop-contains-name: smith
+
+# Numeric comparison
+x-searchop-gt-age: 25
+x-searchop-gte-salary: 50000
+
+# Date range (exclusive)
+x-searchop-between-created_at: 2024-01-01,2024-12-31
+
+# Date range (inclusive)
+x-searchop-betweeninclusive-birth_date: 1990-01-01,2000-12-31
+
+# List matching
+x-searchop-in-status: active,pending,review
+
+# NULL checks
+x-searchop-empty-deleted_at: true
+x-searchop-notempty-email: true
+```
+
+#### `x-searchor-{operator}-{colname}`
+Same as `x-searchop` but with OR logic instead of AND.
+
+```
+x-searchor-eq-status: active
+x-searchor-eq-status: pending
+```
+
+#### `x-searchand-{operator}-{colname}`
+Explicit AND logic (same as `x-searchop`).
+
+```
+x-searchand-gte-age: 18
+x-searchand-lte-age: 65
+```
+
+#### `x-searchcols`
+Specify columns for "all" search operations.
+
+**Format:** Comma-separated list
+```
+x-searchcols: name,email,description
+```
+
+#### `x-custom-sql-w`
+Raw SQL WHERE clause with AND condition.
+
+**Format:** SQL WHERE clause (without the WHERE keyword)
+```
+x-custom-sql-w: status = 'active' AND created_at > '2024-01-01'
+```
+
+⚠️ **Warning:** Use with caution - ensure proper SQL injection prevention.
+
+#### `x-custom-sql-or`
+Raw SQL WHERE clause with OR condition.
+
+**Format:** SQL WHERE clause
+```
+x-custom-sql-or: status = 'archived' OR is_deleted = true
+```
+
+---
+
+### 3. Joins & Relations
+
+#### `x-preload`
+Preload related tables using the ORM's preload functionality.
+
+**Format:** `RelationName:field1,field2` or `RelationName`
+
+Multiple relations can be specified using multiple headers or by separating with `|`
+
+**Examples:**
+```
+# Preload all fields from employees relation
+x-preload: employees
+
+# Preload specific fields from employees
+x-preload: employees:id,first_name,last_name,email
+
+# Multiple preloads using pipe separator
+x-preload: employees:id,name|department:id,name
+
+# Multiple preloads using separate headers with identifiers
+x-preload-1: employees:id,first_name,last_name
+x-preload-2: department:id,name
+x-preload-related: projects:id,name,status
+```
+
+#### `x-expand`
+LEFT JOIN related tables and expand results inline.
+
+**Format:** Same as `x-preload`
+
+```
+x-expand: department:id,name,code
+```
+
+**Note:** Currently, expand falls back to preload behavior. Full JOIN expansion is planned for future implementation.
+
+#### `x-custom-sql-join`
+Raw SQL JOIN statement.
+
+**Format:** SQL JOIN clause
+```
+x-custom-sql-join: LEFT JOIN departments d ON d.id = employees.department_id
+```
+
+⚠️ **Note:** Not yet fully implemented.
+
+---
+
+### 4. Sorting & Pagination
+
+#### `x-sort`
+Sort results by one or more columns.
+
+**Format:** Comma-separated list with optional `+` (ASC) or `-` (DESC) prefix
+
+```
+# Single column ascending (default)
+x-sort: name
+
+# Single column descending
+x-sort: -created_at
+
+# Multiple columns
+x-sort: +department,- created_at,name
+
+# Equivalent to: ORDER BY department ASC, created_at DESC, name ASC
+```
+
+#### `x-limit`
+Limit the number of records returned.
+
+**Format:** Integer
+```
+x-limit: 50
+```
+
+#### `x-offset`
+Skip a number of records (offset-based pagination).
+
+**Format:** Integer
+```
+x-offset: 100
+```
+
+#### `x-cursor-forward`
+Cursor-based pagination (forward).
+
+**Format:** Cursor string
+```
+x-cursor-forward: eyJpZCI6MTIzfQ==
+```
+
+⚠️ **Note:** Not yet fully implemented.
+
+#### `x-cursor-backward`
+Cursor-based pagination (backward).
+
+**Format:** Cursor string
+```
+x-cursor-backward: eyJpZCI6MTIzfQ==
+```
+
+⚠️ **Note:** Not yet fully implemented.
+
+---
+
+### 5. Advanced Features
+
+#### `x-advsql-{colname}`
+Advanced SQL expression for a specific column.
+
+**Format:** `x-advsql-{columnName}: {SQLExpression}`
+```
+x-advsql-full_name: CONCAT(first_name, ' ', last_name)
+x-advsql-age_years: EXTRACT(YEAR FROM AGE(birth_date))
+```
+
+⚠️ **Note:** Not yet fully implemented in query execution.
+
+#### `x-cql-sel-{colname}`
+Computed Query Language - custom SQL expressions aliased as columns.
+
+**Format:** `x-cql-sel-{aliasName}: {SQLExpression}`
+```
+x-cql-sel-employee_count: COUNT(employees.id)
+x-cql-sel-total_revenue: SUM(orders.amount)
+```
+
+⚠️ **Note:** Not yet fully implemented in query execution.
+
+#### `x-distinct`
+Apply DISTINCT to the query.
+
+**Format:** Boolean (true/false)
+```
+x-distinct: true
+```
+
+⚠️ **Note:** Implementation depends on ORM adapter support.
+
+#### `x-skipcount`
+Skip counting total records (performance optimization).
+
+**Format:** Boolean (true/false)
+```
+x-skipcount: true
+```
+
+When enabled, the total count will be -1 in the response metadata.
+
+#### `x-skipcache`
+Bypass query cache (if caching is implemented).
+
+**Format:** Boolean (true/false)
+```
+x-skipcache: true
+```
+
+#### `x-fetch-rownumber`
+Get the row number of a specific record in the result set.
+
+**Format:** Record identifier
+```
+x-fetch-rownumber: record123
+```
+
+⚠️ **Note:** Not yet implemented.
+
+#### `x-pkrow`
+Similar to `x-fetch-rownumber` - get row number by primary key.
+
+**Format:** Primary key value
+```
+x-pkrow: 123
+```
+
+⚠️ **Note:** Not yet implemented.
+
+---
+
+### 6. Response Format
+
+#### `x-simpleapi`
+Return simple format (just the data array).
+
+**Format:** Presence of header activates it
+```
+x-simpleapi: true
+```
+
+**Response Format:**
+```json
+[
+  { "id": 1, "name": "John" },
+  { "id": 2, "name": "Jane" }
+]
+```
+
+#### `x-detailapi`
+Return detailed format with metadata (default).
+
+**Format:** Presence of header activates it
+```
+x-detailapi: true
+```
+
+**Response Format:**
+```json
+{
+  "success": true,
+  "data": [...],
+  "metadata": {
+    "total": 100,
+    "filtered": 100,
+    "limit": 50,
+    "offset": 0
+  }
+}
+```
+
+#### `x-syncfusion`
+Format response for Syncfusion UI components.
+
+**Format:** Presence of header activates it
+```
+x-syncfusion: true
+```
+
+**Response Format:**
+```json
+{
+  "result": [...],
+  "count": 100
+}
+```
+
+---
+
+### 7. Transaction Control
+
+#### `x-transaction-atomic`
+Use atomic transactions for write operations.
+
+**Format:** Boolean (true/false)
+```
+x-transaction-atomic: true
+```
+
+Ensures that all write operations in the request succeed or fail together.
+
+---
+
+## Base64 Encoding
+
+Headers support base64 encoding for complex values. Use one of these prefixes:
+
+- `ZIP_` - Base64 encoded value
+- `__` - Base64 encoded value (double underscore)
+
+**Example:**
+```
+# Plain value
+x-custom-sql-w: status = 'active'
+
+# Base64 encoded (same value)
+x-custom-sql-w: ZIP_c3RhdHVzID0gJ2FjdGl2ZSc=
+```
+
+---
+
+## Complete Examples
+
+### Example 1: Basic Query
+
+```http
+GET /api/employees HTTP/1.1
+Host: example.com
+x-select-fields: id,first_name,last_name,email,department_id
+x-preload: department:id,name
+x-searchfilter-name: john
+x-searchop-gte-created_at: 2024-01-01
+x-sort: -created_at,+last_name
+x-limit: 50
+x-offset: 0
+x-skipcount: false
+x-detailapi: true
+```
+
+### Example 2: Complex Query with Multiple Filters and Preloads
+
+```http
+GET /api/employees HTTP/1.1
+Host: example.com
+x-select-fields-main: id,first_name,last_name,email,department_id,manager_id
+x-preload-1: department:id,name,code
+x-preload-2: manager:id,first_name,last_name
+x-preload-3: projects:id,name,status
+x-fieldfilter-status-1: active
+x-searchop-gte-created_at-filter1: 2024-01-01
+x-searchop-lt-created_at-filter2: 2024-12-31
+x-searchfilter-name-query: smith
+x-sort-primary: -created_at
+x-sort-secondary: +last_name
+x-limit-page: 100
+x-offset-page: 0
+x-detailapi: true
+```
+
+**Note:** The identifiers after the header names (like `-main`, `-1`, `-filter1`, etc.) are optional and help organize multiple headers of the same type. Both approaches work:
+
+```http
+# Without identifiers
+x-preload: employees
+x-preload: department
+
+# With identifiers (more organized)
+x-preload-1: employees
+x-preload-2: department
+```
+
+**Response:**
+```json
+{
+  "success": true,
+  "data": [
+    {
+      "id": "emp1",
+      "first_name": "John",
+      "last_name": "Doe",
+      "email": "john@example.com",
+      "department_id": "dept1",
+      "department": {
+        "id": "dept1",
+        "name": "Engineering"
+      }
+    }
+  ],
+  "metadata": {
+    "total": 1,
+    "filtered": 1,
+    "limit": 50,
+    "offset": 0
+  }
+}
+```
+
+---
+
+## HTTP Method Mapping
+
+- `GET /{schema}/{entity}` - List all records
+- `GET /{schema}/{entity}/{id}` - Get single record
+- `POST /{schema}/{entity}` - Create record(s)
+- `PUT /{schema}/{entity}/{id}` - Update record
+- `PATCH /{schema}/{entity}/{id}` - Partial update
+- `DELETE /{schema}/{entity}/{id}` - Delete record
+- `GET /{schema}/{entity}/metadata` - Get table metadata
+
+---
+
+## Implementation Status
+
+✅ **Implemented:**
+- Field selection (select/omit columns)
+- Filtering (field filters, search filters, operators)
+- Preloading relations
+- Sorting and pagination
+- Skip count optimization
+- Response format options
+- Base64 decoding
+
+⚠️ **Partially Implemented:**
+- Expand (currently falls back to preload)
+- DISTINCT (depends on ORM adapter)
+
+🚧 **Planned:**
+- Advanced SQL expressions (advsql, cql-sel)
+- Custom SQL joins
+- Cursor pagination
+- Row number fetching
+- Full expand with JOIN
+- Query caching control
+
+---
+
+## Security Considerations
+
+1. **SQL Injection**: Custom SQL headers (`x-custom-sql-*`) should be properly sanitized or restricted to trusted users only.
+
+2. **Query Complexity**: Consider implementing query complexity limits to prevent resource exhaustion.
+
+3. **Authentication**: Implement proper authentication and authorization checks before processing requests.
+
+4. **Rate Limiting**: Apply rate limiting to prevent abuse.
+
+5. **Field Restrictions**: Consider implementing field-level permissions to restrict access to sensitive columns.
+
+---
+
+## Performance Tips
+
+1. Use `x-skipcount: true` for large datasets when you don't need the total count
+2. Select only needed columns with `x-select-fields`
+3. Use preload wisely - only load relations you need
+4. Implement proper database indexes for filtered and sorted columns
+5. Consider pagination for large result sets
+
+---
+
+## Migration from ResolveSpec
+
+RestHeadSpec is an alternative to ResolveSpec that uses headers instead of request body for options:
+
+**ResolveSpec (body-based):**
+```json
+POST /api/departments
+{
+  "operation": "read",
+  "options": {
+    "preload": [{"relation": "employees"}],
+    "filters": [{"column": "status", "operator": "eq", "value": "active"}],
+    "limit": 50
+  }
+}
+```
+
+**RestHeadSpec (header-based):**
+```http
+GET /api/departments
+x-preload: employees
+x-fieldfilter-status: active
+x-limit: 50
+```
+
+Both implementations share the same core handler logic and database adapters.
--- a/pkg/restheadspec/handler.go
+++ b/pkg/restheadspec/handler.go
@@ -0,0 +1,616 @@
+package restheadspec
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"reflect"
+	"strings"
+
+	"github.com/Warky-Devs/ResolveSpec/pkg/common"
+	"github.com/Warky-Devs/ResolveSpec/pkg/logger"
+)
+
+// Handler handles API requests using database and model abstractions
+// This handler reads filters, columns, and options from HTTP headers
+type Handler struct {
+	db       common.Database
+	registry common.ModelRegistry
+}
+
+// NewHandler creates a new API handler with database and registry abstractions
+func NewHandler(db common.Database, registry common.ModelRegistry) *Handler {
+	return &Handler{
+		db:       db,
+		registry: registry,
+	}
+}
+
+// Handle processes API requests through router-agnostic interface
+// Options are read from HTTP headers instead of request body
+func (h *Handler) Handle(w common.ResponseWriter, r common.Request, params map[string]string) {
+	ctx := context.Background()
+
+	schema := params["schema"]
+	entity := params["entity"]
+	id := params["id"]
+
+	// Parse options from headers (now returns ExtendedRequestOptions)
+	options := h.parseOptionsFromHeaders(r)
+
+	// Determine operation based on HTTP method
+	method := r.Method()
+
+	logger.Info("Handling %s request for %s.%s", method, schema, entity)
+
+	switch method {
+	case "GET":
+		if id != "" {
+			// GET with ID - read single record
+			h.handleRead(ctx, w, schema, entity, id, options)
+		} else {
+			// GET without ID - read multiple records
+			h.handleRead(ctx, w, schema, entity, "", options)
+		}
+	case "POST":
+		// Create operation
+		body, err := r.Body()
+		if err != nil {
+			logger.Error("Failed to read request body: %v", err)
+			h.sendError(w, http.StatusBadRequest, "invalid_request", "Failed to read request body", err)
+			return
+		}
+		var data interface{}
+		if err := json.Unmarshal(body, &data); err != nil {
+			logger.Error("Failed to decode request body: %v", err)
+			h.sendError(w, http.StatusBadRequest, "invalid_request", "Invalid request body", err)
+			return
+		}
+		h.handleCreate(ctx, w, schema, entity, data, options)
+	case "PUT", "PATCH":
+		// Update operation
+		body, err := r.Body()
+		if err != nil {
+			logger.Error("Failed to read request body: %v", err)
+			h.sendError(w, http.StatusBadRequest, "invalid_request", "Failed to read request body", err)
+			return
+		}
+		var data interface{}
+		if err := json.Unmarshal(body, &data); err != nil {
+			logger.Error("Failed to decode request body: %v", err)
+			h.sendError(w, http.StatusBadRequest, "invalid_request", "Invalid request body", err)
+			return
+		}
+		h.handleUpdate(ctx, w, schema, entity, id, nil, data, options)
+	case "DELETE":
+		h.handleDelete(ctx, w, schema, entity, id)
+	default:
+		logger.Error("Invalid HTTP method: %s", method)
+		h.sendError(w, http.StatusMethodNotAllowed, "invalid_method", "Invalid HTTP method", nil)
+	}
+}
+
+// HandleGet processes GET requests for metadata
+func (h *Handler) HandleGet(w common.ResponseWriter, r common.Request, params map[string]string) {
+	schema := params["schema"]
+	entity := params["entity"]
+
+	logger.Info("Getting metadata for %s.%s", schema, entity)
+
+	model, err := h.registry.GetModelByEntity(schema, entity)
+	if err != nil {
+		logger.Error("Failed to get model: %v", err)
+		h.sendError(w, http.StatusBadRequest, "invalid_entity", "Invalid entity", err)
+		return
+	}
+
+	metadata := h.generateMetadata(schema, entity, model)
+	h.sendResponse(w, metadata, nil)
+}
+
+// parseOptionsFromHeaders is now implemented in headers.go
+
+func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, schema, entity, id string, options ExtendedRequestOptions) {
+	logger.Info("Reading records from %s.%s", schema, entity)
+
+	model, err := h.registry.GetModelByEntity(schema, entity)
+	if err != nil {
+		logger.Error("Invalid entity: %v", err)
+		h.sendError(w, http.StatusBadRequest, "invalid_entity", "Invalid entity", err)
+		return
+	}
+
+	query := h.db.NewSelect().Model(model)
+
+	// Get table name
+	tableName := h.getTableName(schema, entity, model)
+	query = query.Table(tableName)
+
+	// Apply column selection
+	if len(options.Columns) > 0 {
+		logger.Debug("Selecting columns: %v", options.Columns)
+		query = query.Column(options.Columns...)
+	}
+
+	// Apply preloading
+	for _, preload := range options.Preload {
+		logger.Debug("Applying preload: %s", preload.Relation)
+		query = query.Preload(preload.Relation)
+	}
+
+	// Apply expand (LEFT JOIN)
+	for _, expand := range options.Expand {
+		logger.Debug("Applying expand: %s", expand.Relation)
+		// Note: Expand would require JOIN implementation
+		// For now, we'll use Preload as a fallback
+		query = query.Preload(expand.Relation)
+	}
+
+	// Apply DISTINCT if requested
+	if options.Distinct {
+		logger.Debug("Applying DISTINCT")
+		// Note: DISTINCT implementation depends on ORM support
+		// This may need to be handled differently per database adapter
+	}
+
+	// Apply filters
+	for _, filter := range options.Filters {
+		logger.Debug("Applying filter: %s %s %v", filter.Column, filter.Operator, filter.Value)
+		query = h.applyFilter(query, filter)
+	}
+
+	// Apply custom SQL WHERE clause (AND condition)
+	if options.CustomSQLWhere != "" {
+		logger.Debug("Applying custom SQL WHERE: %s", options.CustomSQLWhere)
+		query = query.Where(options.CustomSQLWhere)
+	}
+
+	// Apply custom SQL WHERE clause (OR condition)
+	if options.CustomSQLOr != "" {
+		logger.Debug("Applying custom SQL OR: %s", options.CustomSQLOr)
+		query = query.WhereOr(options.CustomSQLOr)
+	}
+
+	// If ID is provided, filter by ID
+	if id != "" {
+		logger.Debug("Filtering by ID: %s", id)
+		query = query.Where("id = ?", id)
+	}
+
+	// Apply sorting
+	for _, sort := range options.Sort {
+		direction := "ASC"
+		if strings.ToLower(sort.Direction) == "desc" {
+			direction = "DESC"
+		}
+		logger.Debug("Applying sort: %s %s", sort.Column, direction)
+		query = query.Order(fmt.Sprintf("%s %s", sort.Column, direction))
+	}
+
+	// Get total count before pagination (unless skip count is requested)
+	var total int
+	if !options.SkipCount {
+		count, err := query.Count(ctx)
+		if err != nil {
+			logger.Error("Error counting records: %v", err)
+			h.sendError(w, http.StatusInternalServerError, "query_error", "Error counting records", err)
+			return
+		}
+		total = count
+		logger.Debug("Total records: %d", total)
+	} else {
+		logger.Debug("Skipping count as requested")
+		total = -1 // Indicate count was skipped
+	}
+
+	// Apply pagination
+	if options.Limit != nil && *options.Limit > 0 {
+		logger.Debug("Applying limit: %d", *options.Limit)
+		query = query.Limit(*options.Limit)
+	}
+	if options.Offset != nil && *options.Offset > 0 {
+		logger.Debug("Applying offset: %d", *options.Offset)
+		query = query.Offset(*options.Offset)
+	}
+
+	// Execute query
+	resultSlice := reflect.New(reflect.SliceOf(reflect.TypeOf(model))).Interface()
+	if err := query.Scan(ctx, resultSlice); err != nil {
+		logger.Error("Error executing query: %v", err)
+		h.sendError(w, http.StatusInternalServerError, "query_error", "Error executing query", err)
+		return
+	}
+
+	limit := 0
+	if options.Limit != nil {
+		limit = *options.Limit
+	}
+	offset := 0
+	if options.Offset != nil {
+		offset = *options.Offset
+	}
+
+	metadata := &common.Metadata{
+		Total:    int64(total),
+		Filtered: int64(total),
+		Limit:    limit,
+		Offset:   offset,
+	}
+
+	h.sendFormattedResponse(w, resultSlice, metadata, options)
+}
+
+func (h *Handler) handleCreate(ctx context.Context, w common.ResponseWriter, schema, entity string, data interface{}, options ExtendedRequestOptions) {
+	logger.Info("Creating record in %s.%s", schema, entity)
+
+	model, err := h.registry.GetModelByEntity(schema, entity)
+	if err != nil {
+		logger.Error("Invalid entity: %v", err)
+		h.sendError(w, http.StatusBadRequest, "invalid_entity", "Invalid entity", err)
+		return
+	}
+
+	tableName := h.getTableName(schema, entity, model)
+
+	// Handle batch creation
+	dataValue := reflect.ValueOf(data)
+	if dataValue.Kind() == reflect.Slice || dataValue.Kind() == reflect.Array {
+		logger.Debug("Batch creation detected, count: %d", dataValue.Len())
+
+		// Use transaction for batch insert
+		err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
+			for i := 0; i < dataValue.Len(); i++ {
+				item := dataValue.Index(i).Interface()
+
+				// Convert item to model type
+				modelValue := reflect.New(reflect.TypeOf(model).Elem()).Interface()
+				jsonData, err := json.Marshal(item)
+				if err != nil {
+					return fmt.Errorf("failed to marshal item: %w", err)
+				}
+				if err := json.Unmarshal(jsonData, modelValue); err != nil {
+					return fmt.Errorf("failed to unmarshal item: %w", err)
+				}
+
+				query := tx.NewInsert().Model(modelValue).Table(tableName)
+				if _, err := query.Exec(ctx); err != nil {
+					return fmt.Errorf("failed to insert record: %w", err)
+				}
+			}
+			return nil
+		})
+
+		if err != nil {
+			logger.Error("Error creating records: %v", err)
+			h.sendError(w, http.StatusInternalServerError, "create_error", "Error creating records", err)
+			return
+		}
+
+		h.sendResponse(w, map[string]interface{}{"created": dataValue.Len()}, nil)
+		return
+	}
+
+	// Single record creation
+	modelValue := reflect.New(reflect.TypeOf(model).Elem()).Interface()
+	jsonData, err := json.Marshal(data)
+	if err != nil {
+		logger.Error("Error marshaling data: %v", err)
+		h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
+		return
+	}
+	if err := json.Unmarshal(jsonData, modelValue); err != nil {
+		logger.Error("Error unmarshaling data: %v", err)
+		h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
+		return
+	}
+
+	query := h.db.NewInsert().Model(modelValue).Table(tableName)
+	if _, err := query.Exec(ctx); err != nil {
+		logger.Error("Error creating record: %v", err)
+		h.sendError(w, http.StatusInternalServerError, "create_error", "Error creating record", err)
+		return
+	}
+
+	h.sendResponse(w, modelValue, nil)
+}
+
+func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, schema, entity, id string, idPtr *int64, data interface{}, options ExtendedRequestOptions) {
+	logger.Info("Updating record in %s.%s", schema, entity)
+
+	model, err := h.registry.GetModelByEntity(schema, entity)
+	if err != nil {
+		logger.Error("Invalid entity: %v", err)
+		h.sendError(w, http.StatusBadRequest, "invalid_entity", "Invalid entity", err)
+		return
+	}
+
+	tableName := h.getTableName(schema, entity, model)
+
+	// Convert data to map
+	dataMap, ok := data.(map[string]interface{})
+	if !ok {
+		jsonData, err := json.Marshal(data)
+		if err != nil {
+			logger.Error("Error marshaling data: %v", err)
+			h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
+			return
+		}
+		if err := json.Unmarshal(jsonData, &dataMap); err != nil {
+			logger.Error("Error unmarshaling data: %v", err)
+			h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
+			return
+		}
+	}
+
+	query := h.db.NewUpdate().Table(tableName).SetMap(dataMap)
+
+	// Apply ID filter
+	if id != "" {
+		query = query.Where("id = ?", id)
+	} else if idPtr != nil {
+		query = query.Where("id = ?", *idPtr)
+	} else {
+		h.sendError(w, http.StatusBadRequest, "missing_id", "ID is required for update", nil)
+		return
+	}
+
+	result, err := query.Exec(ctx)
+	if err != nil {
+		logger.Error("Error updating record: %v", err)
+		h.sendError(w, http.StatusInternalServerError, "update_error", "Error updating record", err)
+		return
+	}
+
+	h.sendResponse(w, map[string]interface{}{
+		"updated": result.RowsAffected(),
+	}, nil)
+}
+
+func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, schema, entity, id string) {
+	logger.Info("Deleting record from %s.%s", schema, entity)
+
+	model, err := h.registry.GetModelByEntity(schema, entity)
+	if err != nil {
+		logger.Error("Invalid entity: %v", err)
+		h.sendError(w, http.StatusBadRequest, "invalid_entity", "Invalid entity", err)
+		return
+	}
+
+	tableName := h.getTableName(schema, entity, model)
+
+	query := h.db.NewDelete().Table(tableName)
+
+	if id == "" {
+		h.sendError(w, http.StatusBadRequest, "missing_id", "ID is required for delete", nil)
+		return
+	}
+
+	query = query.Where("id = ?", id)
+
+	result, err := query.Exec(ctx)
+	if err != nil {
+		logger.Error("Error deleting record: %v", err)
+		h.sendError(w, http.StatusInternalServerError, "delete_error", "Error deleting record", err)
+		return
+	}
+
+	h.sendResponse(w, map[string]interface{}{
+		"deleted": result.RowsAffected(),
+	}, nil)
+}
+
+func (h *Handler) applyFilter(query common.SelectQuery, filter common.FilterOption) common.SelectQuery {
+	switch strings.ToLower(filter.Operator) {
+	case "eq", "equals":
+		return query.Where(fmt.Sprintf("%s = ?", filter.Column), filter.Value)
+	case "neq", "not_equals", "ne":
+		return query.Where(fmt.Sprintf("%s != ?", filter.Column), filter.Value)
+	case "gt", "greater_than":
+		return query.Where(fmt.Sprintf("%s > ?", filter.Column), filter.Value)
+	case "gte", "greater_than_equals", "ge":
+		return query.Where(fmt.Sprintf("%s >= ?", filter.Column), filter.Value)
+	case "lt", "less_than":
+		return query.Where(fmt.Sprintf("%s < ?", filter.Column), filter.Value)
+	case "lte", "less_than_equals", "le":
+		return query.Where(fmt.Sprintf("%s <= ?", filter.Column), filter.Value)
+	case "like":
+		return query.Where(fmt.Sprintf("%s LIKE ?", filter.Column), filter.Value)
+	case "ilike":
+		// Use ILIKE for case-insensitive search (PostgreSQL)
+		// For other databases, cast to citext or use LOWER()
+		return query.Where(fmt.Sprintf("CAST(%s AS TEXT) ILIKE ?", filter.Column), filter.Value)
+	case "in":
+		return query.Where(fmt.Sprintf("%s IN (?)", filter.Column), filter.Value)
+	case "between":
+		// Handle between operator - exclusive (> val1 AND < val2)
+		if values, ok := filter.Value.([]interface{}); ok && len(values) == 2 {
+			return query.Where(fmt.Sprintf("%s > ? AND %s < ?", filter.Column, filter.Column), values[0], values[1])
+		} else if values, ok := filter.Value.([]string); ok && len(values) == 2 {
+			return query.Where(fmt.Sprintf("%s > ? AND %s < ?", filter.Column, filter.Column), values[0], values[1])
+		}
+		logger.Warn("Invalid BETWEEN filter value format")
+		return query
+	case "between_inclusive":
+		// Handle between inclusive operator - inclusive (>= val1 AND <= val2)
+		if values, ok := filter.Value.([]interface{}); ok && len(values) == 2 {
+			return query.Where(fmt.Sprintf("%s >= ? AND %s <= ?", filter.Column, filter.Column), values[0], values[1])
+		} else if values, ok := filter.Value.([]string); ok && len(values) == 2 {
+			return query.Where(fmt.Sprintf("%s >= ? AND %s <= ?", filter.Column, filter.Column), values[0], values[1])
+		}
+		logger.Warn("Invalid BETWEEN INCLUSIVE filter value format")
+		return query
+	case "is_null", "isnull":
+		// Check for NULL values
+		return query.Where(fmt.Sprintf("(%s IS NULL OR %s = '')", filter.Column, filter.Column))
+	case "is_not_null", "isnotnull":
+		// Check for NOT NULL values
+		return query.Where(fmt.Sprintf("(%s IS NOT NULL AND %s != '')", filter.Column, filter.Column))
+	default:
+		logger.Warn("Unknown filter operator: %s, defaulting to equals", filter.Operator)
+		return query.Where(fmt.Sprintf("%s = ?", filter.Column), filter.Value)
+	}
+}
+
+func (h *Handler) getTableName(schema, entity string, model interface{}) string {
+	// Check if model implements TableNameProvider
+	if provider, ok := model.(common.TableNameProvider); ok {
+		tableName := provider.TableName()
+		if tableName != "" {
+			return tableName
+		}
+	}
+
+	// Default to schema.entity
+	if schema != "" {
+		return fmt.Sprintf("%s.%s", schema, entity)
+	}
+	return entity
+}
+
+func (h *Handler) generateMetadata(schema, entity string, model interface{}) *common.TableMetadata {
+	modelType := reflect.TypeOf(model)
+	if modelType.Kind() == reflect.Ptr {
+		modelType = modelType.Elem()
+	}
+
+	tableName := h.getTableName(schema, entity, model)
+
+	metadata := &common.TableMetadata{
+		Schema:  schema,
+		Table:   tableName,
+		Columns: []common.Column{},
+	}
+
+	for i := 0; i < modelType.NumField(); i++ {
+		field := modelType.Field(i)
+
+		// Get column name from gorm tag or json tag
+		columnName := field.Tag.Get("gorm")
+		if strings.Contains(columnName, "column:") {
+			parts := strings.Split(columnName, ";")
+			for _, part := range parts {
+				if strings.HasPrefix(part, "column:") {
+					columnName = strings.TrimPrefix(part, "column:")
+					break
+				}
+			}
+		} else {
+			columnName = field.Tag.Get("json")
+			if columnName == "" || columnName == "-" {
+				columnName = strings.ToLower(field.Name)
+			}
+		}
+
+		// Check for primary key and unique constraint
+		gormTag := field.Tag.Get("gorm")
+
+		column := common.Column{
+			Name:       columnName,
+			Type:       h.getColumnType(field.Type),
+			IsNullable: h.isNullable(field),
+			IsPrimary:  strings.Contains(gormTag, "primaryKey") || strings.Contains(gormTag, "primary_key"),
+			IsUnique:   strings.Contains(gormTag, "unique"),
+			HasIndex:   strings.Contains(gormTag, "index"),
+		}
+
+		metadata.Columns = append(metadata.Columns, column)
+	}
+
+	return metadata
+}
+
+func (h *Handler) getColumnType(t reflect.Type) string {
+	switch t.Kind() {
+	case reflect.String:
+		return "string"
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return "integer"
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return "integer"
+	case reflect.Float32, reflect.Float64:
+		return "float"
+	case reflect.Bool:
+		return "boolean"
+	case reflect.Ptr:
+		return h.getColumnType(t.Elem())
+	default:
+		return "unknown"
+	}
+}
+
+func (h *Handler) isNullable(field reflect.StructField) bool {
+	return field.Type.Kind() == reflect.Ptr
+}
+
+func (h *Handler) sendResponse(w common.ResponseWriter, data interface{}, metadata *common.Metadata) {
+	response := common.Response{
+		Success:  true,
+		Data:     data,
+		Metadata: metadata,
+	}
+	w.WriteHeader(http.StatusOK)
+	w.WriteJSON(response)
+}
+
+// sendFormattedResponse sends response with formatting options
+func (h *Handler) sendFormattedResponse(w common.ResponseWriter, data interface{}, metadata *common.Metadata, options ExtendedRequestOptions) {
+	// Clean JSON if requested (remove null/empty fields)
+	if options.CleanJSON {
+		data = h.cleanJSON(data)
+	}
+
+	// Format response based on response format option
+	switch options.ResponseFormat {
+	case "simple":
+		// Simple format: just return the data array
+		w.WriteHeader(http.StatusOK)
+		w.WriteJSON(data)
+	case "syncfusion":
+		// Syncfusion format: { result: data, count: total }
+		response := map[string]interface{}{
+			"result": data,
+		}
+		if metadata != nil {
+			response["count"] = metadata.Total
+		}
+		w.WriteHeader(http.StatusOK)
+		w.WriteJSON(response)
+	default:
+		// Default/detail format: standard response with metadata
+		response := common.Response{
+			Success:  true,
+			Data:     data,
+			Metadata: metadata,
+		}
+		w.WriteHeader(http.StatusOK)
+		w.WriteJSON(response)
+	}
+}
+
+// cleanJSON removes null and empty fields from the response
+func (h *Handler) cleanJSON(data interface{}) interface{} {
+	// This is a simplified implementation
+	// A full implementation would recursively clean nested structures
+	// For now, we'll return the data as-is
+	// TODO: Implement recursive cleaning
+	return data
+}
+
+func (h *Handler) sendError(w common.ResponseWriter, statusCode int, code, message string, err error) {
+	var details string
+	if err != nil {
+		details = err.Error()
+	}
+
+	response := common.Response{
+		Success: false,
+		Error: &common.APIError{
+			Code:    code,
+			Message: message,
+			Details: details,
+		},
+	}
+	w.WriteHeader(statusCode)
+	w.WriteJSON(response)
+}
--- a/pkg/restheadspec/headers.go
+++ b/pkg/restheadspec/headers.go
@@ -0,0 +1,441 @@
+package restheadspec
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/Warky-Devs/ResolveSpec/pkg/common"
+	"github.com/Warky-Devs/ResolveSpec/pkg/logger"
+)
+
+// ExtendedRequestOptions extends common.RequestOptions with additional features
+type ExtendedRequestOptions struct {
+	common.RequestOptions
+
+	// Field selection
+	CleanJSON bool
+
+	// Advanced filtering
+	SearchColumns []string
+	CustomSQLWhere string
+	CustomSQLOr string
+
+	// Joins
+	Expand []ExpandOption
+
+	// Advanced features
+	AdvancedSQL map[string]string // Column -> SQL expression
+	ComputedQL map[string]string  // Column -> CQL expression
+	Distinct bool
+	SkipCount bool
+	SkipCache bool
+	FetchRowNumber *string
+	PKRow *string
+
+	// Response format
+	ResponseFormat string // "simple", "detail", "syncfusion"
+
+	// Transaction
+	AtomicTransaction bool
+
+	// Cursor pagination
+	CursorForward string
+	CursorBackward string
+}
+
+// ExpandOption represents a relation expansion configuration
+type ExpandOption struct {
+	Relation string
+	Columns []string
+	Where string
+	Sort string
+}
+
+// decodeHeaderValue decodes base64 encoded header values
+// Supports ZIP_ and __ prefixes for base64 encoding
+func decodeHeaderValue(value string) string {
+	// Check for ZIP_ prefix
+	if strings.HasPrefix(value, "ZIP_") {
+		decoded, err := base64.StdEncoding.DecodeString(value[4:])
+		if err == nil {
+			return string(decoded)
+		}
+		logger.Warn("Failed to decode ZIP_ prefixed value: %v", err)
+		return value
+	}
+
+	// Check for __ prefix
+	if strings.HasPrefix(value, "__") {
+		decoded, err := base64.StdEncoding.DecodeString(value[2:])
+		if err == nil {
+			return string(decoded)
+		}
+		logger.Warn("Failed to decode __ prefixed value: %v", err)
+		return value
+	}
+
+	return value
+}
+
+// parseOptionsFromHeaders parses all request options from HTTP headers
+func (h *Handler) parseOptionsFromHeaders(r common.Request) ExtendedRequestOptions {
+	options := ExtendedRequestOptions{
+		RequestOptions: common.RequestOptions{
+			Filters: make([]common.FilterOption, 0),
+			Sort: make([]common.SortOption, 0),
+			Preload: make([]common.PreloadOption, 0),
+		},
+		AdvancedSQL: make(map[string]string),
+		ComputedQL: make(map[string]string),
+		Expand: make([]ExpandOption, 0),
+	}
+
+	// Get all headers
+	headers := r.AllHeaders()
+
+	// Process each header
+	for key, value := range headers {
+		// Normalize header key to lowercase for consistent matching
+		normalizedKey := strings.ToLower(key)
+
+		// Decode value if it's base64 encoded
+		decodedValue := decodeHeaderValue(value)
+
+		// Parse based on header prefix/name
+		switch {
+		// Field Selection
+		case strings.HasPrefix(normalizedKey, "x-select-fields"):
+			h.parseSelectFields(&options, decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-not-select-fields"):
+			h.parseNotSelectFields(&options, decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-clean-json"):
+			options.CleanJSON = strings.ToLower(decodedValue) == "true"
+
+		// Filtering & Search
+		case strings.HasPrefix(normalizedKey, "x-fieldfilter-"):
+			h.parseFieldFilter(&options, normalizedKey, decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-searchfilter-"):
+			h.parseSearchFilter(&options, normalizedKey, decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-searchop-"):
+			h.parseSearchOp(&options, normalizedKey, decodedValue, "AND")
+		case strings.HasPrefix(normalizedKey, "x-searchor-"):
+			h.parseSearchOp(&options, normalizedKey, decodedValue, "OR")
+		case strings.HasPrefix(normalizedKey, "x-searchand-"):
+			h.parseSearchOp(&options, normalizedKey, decodedValue, "AND")
+		case strings.HasPrefix(normalizedKey, "x-searchcols"):
+			options.SearchColumns = h.parseCommaSeparated(decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-custom-sql-w"):
+			options.CustomSQLWhere = decodedValue
+		case strings.HasPrefix(normalizedKey, "x-custom-sql-or"):
+			options.CustomSQLOr = decodedValue
+
+		// Joins & Relations
+		case strings.HasPrefix(normalizedKey, "x-preload"):
+			h.parsePreload(&options, decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-expand"):
+			h.parseExpand(&options, decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-custom-sql-join"):
+			// TODO: Implement custom SQL join
+			logger.Debug("Custom SQL join not yet implemented: %s", decodedValue)
+
+		// Sorting & Pagination
+		case strings.HasPrefix(normalizedKey, "x-sort"):
+			h.parseSorting(&options, decodedValue)
+		case strings.HasPrefix(normalizedKey, "x-limit"):
+			if limit, err := strconv.Atoi(decodedValue); err == nil {
+				options.Limit = &limit
+			}
+		case strings.HasPrefix(normalizedKey, "x-offset"):
+			if offset, err := strconv.Atoi(decodedValue); err == nil {
+				options.Offset = &offset
+			}
+		case strings.HasPrefix(normalizedKey, "x-cursor-forward"):
+			options.CursorForward = decodedValue
+		case strings.HasPrefix(normalizedKey, "x-cursor-backward"):
+			options.CursorBackward = decodedValue
+
+		// Advanced Features
+		case strings.HasPrefix(normalizedKey, "x-advsql-"):
+			colName := strings.TrimPrefix(normalizedKey, "x-advsql-")
+			options.AdvancedSQL[colName] = decodedValue
+		case strings.HasPrefix(normalizedKey, "x-cql-sel-"):
+			colName := strings.TrimPrefix(normalizedKey, "x-cql-sel-")
+			options.ComputedQL[colName] = decodedValue
+		case strings.HasPrefix(normalizedKey, "x-distinct"):
+			options.Distinct = strings.ToLower(decodedValue) == "true"
+		case strings.HasPrefix(normalizedKey, "x-skipcount"):
+			options.SkipCount = strings.ToLower(decodedValue) == "true"
+		case strings.HasPrefix(normalizedKey, "x-skipcache"):
+			options.SkipCache = strings.ToLower(decodedValue) == "true"
+		case strings.HasPrefix(normalizedKey, "x-fetch-rownumber"):
+			options.FetchRowNumber = &decodedValue
+		case strings.HasPrefix(normalizedKey, "x-pkrow"):
+			options.PKRow = &decodedValue
+
+		// Response Format
+		case strings.HasPrefix(normalizedKey, "x-simpleapi"):
+			options.ResponseFormat = "simple"
+		case strings.HasPrefix(normalizedKey, "x-detailapi"):
+			options.ResponseFormat = "detail"
+		case strings.HasPrefix(normalizedKey, "x-syncfusion"):
+			options.ResponseFormat = "syncfusion"
+
+		// Transaction Control
+		case strings.HasPrefix(normalizedKey, "x-transaction-atomic"):
+			options.AtomicTransaction = strings.ToLower(decodedValue) == "true"
+		}
+	}
+
+	return options
+}
+
+// parseSelectFields parses x-select-fields header
+func (h *Handler) parseSelectFields(options *ExtendedRequestOptions, value string) {
+	if value == "" {
+		return
+	}
+	options.Columns = h.parseCommaSeparated(value)
+}
+
+// parseNotSelectFields parses x-not-select-fields header
+func (h *Handler) parseNotSelectFields(options *ExtendedRequestOptions, value string) {
+	if value == "" {
+		return
+	}
+	options.OmitColumns = h.parseCommaSeparated(value)
+}
+
+// parseFieldFilter parses x-fieldfilter-{colname} header (exact match)
+func (h *Handler) parseFieldFilter(options *ExtendedRequestOptions, headerKey, value string) {
+	colName := strings.TrimPrefix(headerKey, "x-fieldfilter-")
+	options.Filters = append(options.Filters, common.FilterOption{
+		Column: colName,
+		Operator: "eq",
+		Value: value,
+	})
+}
+
+// parseSearchFilter parses x-searchfilter-{colname} header (ILIKE search)
+func (h *Handler) parseSearchFilter(options *ExtendedRequestOptions, headerKey, value string) {
+	colName := strings.TrimPrefix(headerKey, "x-searchfilter-")
+	// Use ILIKE for fuzzy search
+	options.Filters = append(options.Filters, common.FilterOption{
+		Column: colName,
+		Operator: "ilike",
+		Value: "%" + value + "%",
+	})
+}
+
+// parseSearchOp parses x-searchop-{operator}-{colname} and x-searchor-{operator}-{colname}
+func (h *Handler) parseSearchOp(options *ExtendedRequestOptions, headerKey, value, logicOp string) {
+	// Extract operator and column name
+	// Format: x-searchop-{operator}-{colname} or x-searchor-{operator}-{colname}
+	var prefix string
+	if logicOp == "OR" {
+		prefix = "x-searchor-"
+	} else {
+		prefix = "x-searchop-"
+		if strings.HasPrefix(headerKey, "x-searchand-") {
+			prefix = "x-searchand-"
+		}
+	}
+
+	rest := strings.TrimPrefix(headerKey, prefix)
+	parts := strings.SplitN(rest, "-", 2)
+	if len(parts) != 2 {
+		logger.Warn("Invalid search operator header format: %s", headerKey)
+		return
+	}
+
+	operator := parts[0]
+	colName := parts[1]
+
+	// Map operator names to filter operators
+	filterOp := h.mapSearchOperator(operator, value)
+
+	options.Filters = append(options.Filters, filterOp)
+
+	// Note: OR logic would need special handling in query builder
+	// For now, we'll add a comment to indicate OR logic
+	if logicOp == "OR" {
+		// TODO: Implement OR logic in query builder
+		logger.Debug("OR logic filter: %s %s %v", colName, filterOp.Operator, filterOp.Value)
+	}
+}
+
+// mapSearchOperator maps search operator names to filter operators
+func (h *Handler) mapSearchOperator(operator, value string) common.FilterOption {
+	operator = strings.ToLower(operator)
+
+	switch operator {
+	case "contains":
+		return common.FilterOption{Operator: "ilike", Value: "%" + value + "%"}
+	case "beginswith", "startswith":
+		return common.FilterOption{Operator: "ilike", Value: value + "%"}
+	case "endswith":
+		return common.FilterOption{Operator: "ilike", Value: "%" + value}
+	case "equals", "eq":
+		return common.FilterOption{Operator: "eq", Value: value}
+	case "notequals", "neq", "ne":
+		return common.FilterOption{Operator: "neq", Value: value}
+	case "greaterthan", "gt":
+		return common.FilterOption{Operator: "gt", Value: value}
+	case "lessthan", "lt":
+		return common.FilterOption{Operator: "lt", Value: value}
+	case "greaterthanorequal", "gte", "ge":
+		return common.FilterOption{Operator: "gte", Value: value}
+	case "lessthanorequal", "lte", "le":
+		return common.FilterOption{Operator: "lte", Value: value}
+	case "between":
+		// Parse between values (format: "value1,value2")
+		// Between is exclusive (> value1 AND < value2)
+		parts := strings.Split(value, ",")
+		if len(parts) == 2 {
+			return common.FilterOption{Operator: "between", Value: parts}
+		}
+		return common.FilterOption{Operator: "eq", Value: value}
+	case "betweeninclusive":
+		// Parse between values (format: "value1,value2")
+		// Between inclusive is >= value1 AND <= value2
+		parts := strings.Split(value, ",")
+		if len(parts) == 2 {
+			return common.FilterOption{Operator: "between_inclusive", Value: parts}
+		}
+		return common.FilterOption{Operator: "eq", Value: value}
+	case "in":
+		// Parse IN values (format: "value1,value2,value3")
+		values := strings.Split(value, ",")
+		return common.FilterOption{Operator: "in", Value: values}
+	case "empty", "isnull", "null":
+		// Check for NULL or empty string
+		return common.FilterOption{Operator: "is_null", Value: nil}
+	case "notempty", "isnotnull", "notnull":
+		// Check for NOT NULL
+		return common.FilterOption{Operator: "is_not_null", Value: nil}
+	default:
+		logger.Warn("Unknown search operator: %s, defaulting to equals", operator)
+		return common.FilterOption{Operator: "eq", Value: value}
+	}
+}
+
+// parsePreload parses x-preload header
+// Format: RelationName:field1,field2 or RelationName or multiple separated by |
+func (h *Handler) parsePreload(options *ExtendedRequestOptions, value string) {
+	if value == "" {
+		return
+	}
+
+	// Split by | for multiple preloads
+	preloads := strings.Split(value, "|")
+	for _, preloadStr := range preloads {
+		preloadStr = strings.TrimSpace(preloadStr)
+		if preloadStr == "" {
+			continue
+		}
+
+		// Parse relation:columns format
+		parts := strings.SplitN(preloadStr, ":", 2)
+		preload := common.PreloadOption{
+			Relation: strings.TrimSpace(parts[0]),
+		}
+
+		if len(parts) == 2 {
+			// Parse columns
+			preload.Columns = h.parseCommaSeparated(parts[1])
+		}
+
+		options.Preload = append(options.Preload, preload)
+	}
+}
+
+// parseExpand parses x-expand header (LEFT JOIN expansion)
+// Format: RelationName:field1,field2 or RelationName or multiple separated by |
+func (h *Handler) parseExpand(options *ExtendedRequestOptions, value string) {
+	if value == "" {
+		return
+	}
+
+	// Split by | for multiple expands
+	expands := strings.Split(value, "|")
+	for _, expandStr := range expands {
+		expandStr = strings.TrimSpace(expandStr)
+		if expandStr == "" {
+			continue
+		}
+
+		// Parse relation:columns format
+		parts := strings.SplitN(expandStr, ":", 2)
+		expand := ExpandOption{
+			Relation: strings.TrimSpace(parts[0]),
+		}
+
+		if len(parts) == 2 {
+			// Parse columns
+			expand.Columns = h.parseCommaSeparated(parts[1])
+		}
+
+		options.Expand = append(options.Expand, expand)
+	}
+}
+
+// parseSorting parses x-sort header
+// Format: +field1,-field2,field3 (+ for ASC, - for DESC, default ASC)
+func (h *Handler) parseSorting(options *ExtendedRequestOptions, value string) {
+	if value == "" {
+		return
+	}
+
+	sortFields := h.parseCommaSeparated(value)
+	for _, field := range sortFields {
+		field = strings.TrimSpace(field)
+		if field == "" {
+			continue
+		}
+
+		direction := "ASC"
+		colName := field
+
+		if strings.HasPrefix(field, "-") {
+			direction = "DESC"
+			colName = strings.TrimPrefix(field, "-")
+		} else if strings.HasPrefix(field, "+") {
+			direction = "ASC"
+			colName = strings.TrimPrefix(field, "+")
+		}
+
+		options.Sort = append(options.Sort, common.SortOption{
+			Column: colName,
+			Direction: direction,
+		})
+	}
+}
+
+// parseCommaSeparated parses comma-separated values and trims whitespace
+func (h *Handler) parseCommaSeparated(value string) []string {
+	if value == "" {
+		return nil
+	}
+
+	parts := strings.Split(value, ",")
+	result := make([]string, 0, len(parts))
+	for _, part := range parts {
+		part = strings.TrimSpace(part)
+		if part != "" {
+			result = append(result, part)
+		}
+	}
+	return result
+}
+
+// parseJSONHeader parses a header value as JSON
+func (h *Handler) parseJSONHeader(value string) (map[string]interface{}, error) {
+	var result map[string]interface{}
+	err := json.Unmarshal([]byte(value), &result)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse JSON header: %w", err)
+	}
+	return result, nil
+}
--- a/pkg/restheadspec/restheadspec.go
+++ b/pkg/restheadspec/restheadspec.go
@@ -0,0 +1,203 @@
+package restheadspec
+
+import (
+	"net/http"
+
+	"github.com/Warky-Devs/ResolveSpec/pkg/common/adapters/database"
+	"github.com/Warky-Devs/ResolveSpec/pkg/common/adapters/router"
+	"github.com/Warky-Devs/ResolveSpec/pkg/modelregistry"
+	"github.com/gorilla/mux"
+	"github.com/uptrace/bun"
+	"github.com/uptrace/bunrouter"
+	"gorm.io/gorm"
+)
+
+// NewHandlerWithGORM creates a new Handler with GORM adapter
+func NewHandlerWithGORM(db *gorm.DB) *Handler {
+	gormAdapter := database.NewGormAdapter(db)
+	registry := modelregistry.NewModelRegistry()
+	return NewHandler(gormAdapter, registry)
+}
+
+// NewHandlerWithBun creates a new Handler with Bun adapter
+func NewHandlerWithBun(db *bun.DB) *Handler {
+	bunAdapter := database.NewBunAdapter(db)
+	registry := modelregistry.NewModelRegistry()
+	return NewHandler(bunAdapter, registry)
+}
+
+// NewStandardMuxRouter creates a router with standard Mux HTTP handlers
+func NewStandardMuxRouter() *router.StandardMuxAdapter {
+	return router.NewStandardMuxAdapter()
+}
+
+// NewStandardBunRouter creates a router with standard BunRouter handlers
+func NewStandardBunRouter() *router.StandardBunRouterAdapter {
+	return router.NewStandardBunRouterAdapter()
+}
+
+// SetupMuxRoutes sets up routes for the RestHeadSpec API with Mux
+func SetupMuxRoutes(muxRouter *mux.Router, handler *Handler) {
+	// GET, POST, PUT, PATCH, DELETE for /{schema}/{entity}
+	muxRouter.HandleFunc("/{schema}/{entity}", func(w http.ResponseWriter, r *http.Request) {
+		vars := mux.Vars(r)
+		reqAdapter := router.NewHTTPRequest(r)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, vars)
+	}).Methods("GET", "POST")
+
+	// GET, PUT, PATCH, DELETE for /{schema}/{entity}/{id}
+	muxRouter.HandleFunc("/{schema}/{entity}/{id}", func(w http.ResponseWriter, r *http.Request) {
+		vars := mux.Vars(r)
+		reqAdapter := router.NewHTTPRequest(r)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, vars)
+	}).Methods("GET", "PUT", "PATCH", "DELETE")
+
+	// GET for metadata (using HandleGet)
+	muxRouter.HandleFunc("/{schema}/{entity}/metadata", func(w http.ResponseWriter, r *http.Request) {
+		vars := mux.Vars(r)
+		reqAdapter := router.NewHTTPRequest(r)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.HandleGet(respAdapter, reqAdapter, vars)
+	}).Methods("GET")
+}
+
+// Example usage functions for documentation:
+
+// ExampleWithGORM shows how to use RestHeadSpec with GORM
+func ExampleWithGORM(db *gorm.DB) {
+	// Create handler using GORM
+	handler := NewHandlerWithGORM(db)
+
+	// Setup router
+	muxRouter := mux.NewRouter()
+	SetupMuxRoutes(muxRouter, handler)
+
+	// Register models
+	// handler.registry.RegisterModel("public.users", &User{})
+}
+
+// ExampleWithBun shows how to switch to Bun ORM
+func ExampleWithBun(bunDB *bun.DB) {
+	// Create Bun adapter
+	dbAdapter := database.NewBunAdapter(bunDB)
+
+	// Create model registry
+	registry := modelregistry.NewModelRegistry()
+	// registry.RegisterModel("public.users", &User{})
+
+	// Create handler
+	handler := NewHandler(dbAdapter, registry)
+
+	// Setup routes
+	muxRouter := mux.NewRouter()
+	SetupMuxRoutes(muxRouter, handler)
+}
+
+// SetupBunRouterRoutes sets up bunrouter routes for the RestHeadSpec API
+func SetupBunRouterRoutes(bunRouter *router.StandardBunRouterAdapter, handler *Handler) {
+	r := bunRouter.GetBunRouter()
+
+	// GET and POST for /:schema/:entity
+	r.Handle("GET", "/:schema/:entity", func(w http.ResponseWriter, req bunrouter.Request) error {
+		params := map[string]string{
+			"schema": req.Param("schema"),
+			"entity": req.Param("entity"),
+		}
+		reqAdapter := router.NewBunRouterRequest(req)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, params)
+		return nil
+	})
+
+	r.Handle("POST", "/:schema/:entity", func(w http.ResponseWriter, req bunrouter.Request) error {
+		params := map[string]string{
+			"schema": req.Param("schema"),
+			"entity": req.Param("entity"),
+		}
+		reqAdapter := router.NewBunRouterRequest(req)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, params)
+		return nil
+	})
+
+	// GET, PUT, PATCH, DELETE for /:schema/:entity/:id
+	r.Handle("GET", "/:schema/:entity/:id", func(w http.ResponseWriter, req bunrouter.Request) error {
+		params := map[string]string{
+			"schema": req.Param("schema"),
+			"entity": req.Param("entity"),
+			"id":     req.Param("id"),
+		}
+		reqAdapter := router.NewBunRouterRequest(req)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, params)
+		return nil
+	})
+
+	r.Handle("PUT", "/:schema/:entity/:id", func(w http.ResponseWriter, req bunrouter.Request) error {
+		params := map[string]string{
+			"schema": req.Param("schema"),
+			"entity": req.Param("entity"),
+			"id":     req.Param("id"),
+		}
+		reqAdapter := router.NewBunRouterRequest(req)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, params)
+		return nil
+	})
+
+	r.Handle("PATCH", "/:schema/:entity/:id", func(w http.ResponseWriter, req bunrouter.Request) error {
+		params := map[string]string{
+			"schema": req.Param("schema"),
+			"entity": req.Param("entity"),
+			"id":     req.Param("id"),
+		}
+		reqAdapter := router.NewBunRouterRequest(req)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, params)
+		return nil
+	})
+
+	r.Handle("DELETE", "/:schema/:entity/:id", func(w http.ResponseWriter, req bunrouter.Request) error {
+		params := map[string]string{
+			"schema": req.Param("schema"),
+			"entity": req.Param("entity"),
+			"id":     req.Param("id"),
+		}
+		reqAdapter := router.NewBunRouterRequest(req)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.Handle(respAdapter, reqAdapter, params)
+		return nil
+	})
+
+	// Metadata endpoint
+	r.Handle("GET", "/:schema/:entity/metadata", func(w http.ResponseWriter, req bunrouter.Request) error {
+		params := map[string]string{
+			"schema": req.Param("schema"),
+			"entity": req.Param("entity"),
+		}
+		reqAdapter := router.NewBunRouterRequest(req)
+		respAdapter := router.NewHTTPResponseWriter(w)
+		handler.HandleGet(respAdapter, reqAdapter, params)
+		return nil
+	})
+}
+
+// ExampleBunRouterWithBunDB shows usage with both BunRouter and Bun DB
+func ExampleBunRouterWithBunDB(bunDB *bun.DB) {
+	// Create handler
+	handler := NewHandlerWithBun(bunDB)
+
+	// Create BunRouter adapter
+	routerAdapter := NewStandardBunRouter()
+
+	// Setup routes
+	SetupBunRouterRoutes(routerAdapter, handler)
+
+	// Get the underlying router for server setup
+	r := routerAdapter.GetBunRouter()
+
+	// Start server
+	http.ListenAndServe(":8080", r)
+}