Empty sort appended bug fix

.golangci.bck.yml

@@ -0,0 +1,110 @@
+run:
+  timeout: 5m
+  tests: true
+  skip-dirs:
+    - vendor
+    - .github
+
+linters:
+  enable:
+    - errcheck
+    - gosimple
+    - govet
+    - ineffassign
+    - staticcheck
+    - unused
+    - gofmt
+    - goimports
+    - misspell
+    - gocritic
+    - revive
+    - stylecheck
+  disable:
+    - typecheck # Can cause issues with generics in some cases
+
+linters-settings:
+  errcheck:
+    check-type-assertions: false
+    check-blank: false
+
+  govet:
+    check-shadowing: false
+
+  gofmt:
+    simplify: true
+
+  goimports:
+    local-prefixes: github.com/bitechdev/ResolveSpec
+
+  gocritic:
+    enabled-checks:
+      - appendAssign
+      - assignOp
+      - boolExprSimplify
+      - builtinShadow
+      - captLocal
+      - caseOrder
+      - defaultCaseOrder
+      - dupArg
+      - dupBranchBody
+      - dupCase
+      - dupSubExpr
+      - elseif
+      - emptyFallthrough
+      - equalFold
+      - flagName
+      - ifElseChain
+      - indexAlloc
+      - initClause
+      - methodExprCall
+      - nilValReturn
+      - rangeExprCopy
+      - rangeValCopy
+      - regexpMust
+      - singleCaseSwitch
+      - sloppyLen
+      - stringXbytes
+      - switchTrue
+      - typeAssertChain
+      - typeSwitchVar
+      - underef
+      - unlabelStmt
+      - unnamedResult
+      - unnecessaryBlock
+      - weakCond
+      - yodaStyleExpr
+
+  revive:
+    rules:
+      - name: exported
+        disabled: true
+      - name: package-comments
+        disabled: true
+
+issues:
+  exclude-use-default: false
+  max-issues-per-linter: 0
+  max-same-issues: 0
+
+  # Exclude some linters from running on tests files
+  exclude-rules:
+    - path: _test\.go
+      linters:
+        - errcheck
+        - dupl
+        - gosec
+        - gocritic
+
+    # Ignore "error return value not checked" for defer statements
+    - linters:
+        - errcheck
+      text: "Error return value of .((os\\.)?std(out|err)\\..*|.*Close|.*Flush|os\\.Remove(All)?|.*print(f|ln)?|os\\.(Un)?Setenv). is not checked"
+
+    # Ignore complexity in test files
+    - path: _test\.go
+      text: "cognitive complexity|cyclomatic complexity"
+
+output:
+  format: colored-line-number
+  print-issued-lines: true
+  print-linter-name: true

.vscode/tasks.json

@@ -24,21 +24,63 @@
 			"type": "go",
 			"label": "go: test workspace",
 			"command": "test",
-			
 			"options": {
-				"env": {				
-					"CGO_ENABLED": "0"
-				},
-				"cwd": "${workspaceFolder}/bin",
+				"cwd": "${workspaceFolder}"
 			},
 			"args": [
-				"../..."
+				"-v",
+				"-race",
+				"-coverprofile=coverage.out",
+				"-covermode=atomic",
+				"./..."
 			],
 			"problemMatcher": [
 				"$go"
 			],
-			"group": "build",
-			
+			"group": {
+				"kind": "test",
+				"isDefault": true
+			},
+			"presentation": {
+				"reveal": "always",
+				"panel": "new"
+			}
 		},
+		{
+			"type": "shell",
+			"label": "go: vet workspace",
+			"command": "go vet ./...",
+			"options": {
+				"cwd": "${workspaceFolder}"
+			},
+			"problemMatcher": [
+				"$go"
+			],
+			"group": "test"
+		},
+		{
+			"type": "shell",
+			"label": "go: lint workspace",
+			"command": "golangci-lint run --timeout=5m",
+			"options": {
+				"cwd": "${workspaceFolder}"
+			},
+			"problemMatcher": [],
+			"group": "test"
+		},
+		{
+			"type": "shell",
+			"label": "go: full test suite",
+			"dependsOrder": "sequence",
+			"dependsOn": [
+				"go: vet workspace",
+				"go: test workspace"
+			],
+			"problemMatcher": [],
+			"group": {
+				"kind": "test",
+				"isDefault": false
+			}
+		}
 	]
 }

README.md

@@ -32,8 +32,9 @@ Both share the same core architecture and provide dynamic data querying, relatio
   - [Lifecycle Hooks](#lifecycle-hooks)
   - [Cursor Pagination](#cursor-pagination)
 - [Example Usage](#example-usage)
+  - [Recursive CRUD Operations](#recursive-crud-operations-)
 - [Testing](#testing)
-- [What's New in v2.0](#whats-new-in-v20)
+- [What's New](#whats-new)
 
 ## Features
 
@@ -45,6 +46,7 @@ Both share the same core architecture and provide dynamic data querying, relatio
 - **Pagination**: Built-in limit/offset and cursor-based pagination
 - **Computed Columns**: Define virtual columns for complex calculations
 - **Custom Operators**: Add custom SQL conditions when needed
+- **🆕 Recursive CRUD Handler**: Automatically handle nested object graphs with foreign key resolution and per-record operation control via `_request` field
 
 ### Architecture (v2.0+)
 - **🆕 Database Agnostic**: Works with GORM, Bun, or any database layer through adapters
@@ -342,6 +344,92 @@ POST /core/users
 }
 ```
 
+### Recursive CRUD Operations (🆕)
+
+ResolveSpec now supports automatic handling of nested object graphs with intelligent foreign key resolution. This allows you to create, update, or delete entire object hierarchies in a single request.
+
+#### Creating Nested Objects
+
+```json
+POST /core/users
+{
+  "operation": "create",
+  "data": {
+    "name": "John Doe",
+    "email": "john@example.com",
+    "posts": [
+      {
+        "title": "My First Post",
+        "content": "Hello World",
+        "tags": [
+          {"name": "tech"},
+          {"name": "programming"}
+        ]
+      },
+      {
+        "title": "Second Post",
+        "content": "More content"
+      }
+    ],
+    "profile": {
+      "bio": "Software Developer",
+      "website": "https://example.com"
+    }
+  }
+}
+```
+
+#### Per-Record Operation Control with `_request`
+
+Control individual operations for each nested record using the special `_request` field:
+
+```json
+POST /core/users/123
+{
+  "operation": "update",
+  "data": {
+    "name": "John Updated",
+    "posts": [
+      {
+        "_request": "insert",
+        "title": "New Post",
+        "content": "Fresh content"
+      },
+      {
+        "_request": "update",
+        "id": 456,
+        "title": "Updated Post Title"
+      },
+      {
+        "_request": "delete",
+        "id": 789
+      }
+    ]
+  }
+}
+```
+
+**Supported `_request` values**:
+- `insert` - Create a new related record
+- `update` - Update an existing related record
+- `delete` - Delete a related record
+- `upsert` - Create if doesn't exist, update if exists
+
+#### How It Works
+
+1. **Automatic Foreign Key Resolution**: Parent IDs are automatically propagated to child records
+2. **Recursive Processing**: Handles nested relationships at any depth
+3. **Transaction Safety**: All operations execute within database transactions
+4. **Relationship Detection**: Automatically detects belongsTo, hasMany, hasOne, and many2many relationships
+5. **Flexible Operations**: Mix create, update, and delete operations in a single request
+
+#### Benefits
+
+- Reduce API round trips for complex object graphs
+- Maintain referential integrity automatically
+- Simplify client-side code
+- Atomic operations with automatic rollback on errors
+
 ## Installation
 
 ```bash
@@ -811,6 +899,25 @@ This project is licensed under the MIT License - see the [LICENSE](LICENSE) file
 
 ### v2.1 (Latest)
 
+**Recursive CRUD Handler (🆕 Nov 11, 2025)**:
+- **Nested Object Graphs**: Automatically handle complex object hierarchies with parent-child relationships
+- **Foreign Key Resolution**: Automatic propagation of parent IDs to child records
+- **Per-Record Operations**: Control create/update/delete operations per record via `_request` field
+- **Transaction Safety**: All nested operations execute atomically within database transactions
+- **Relationship Detection**: Automatic detection of belongsTo, hasMany, hasOne, and many2many relationships
+- **Deep Nesting Support**: Handle relationships at any depth level
+- **Mixed Operations**: Combine insert, update, and delete operations in a single request
+
+**Primary Key Improvements (Nov 11, 2025)**:
+- **GetPrimaryKeyName**: Enhanced primary key detection for better preload and ID field handling
+- **Better GORM/Bun Support**: Improved compatibility with both ORMs for primary key operations
+- **Computed Column Support**: Fixed computed columns functionality across handlers
+
+**Database Adapter Enhancements (Nov 11, 2025)**:
+- **Bun ORM Relations**: Using Scan model method for better has-many and many-to-many relationship handling
+- **Model Method Support**: Enhanced query building with proper model registration
+- **Improved Type Safety**: Better handling of relationship queries with type-aware scanning
+
 **RestHeadSpec - Header-Based REST API**:
 - **Header-Based Querying**: All query options via HTTP headers instead of request body
 - **Lifecycle Hooks**: Before/after hooks for create, read, update, delete operations
@@ -826,6 +933,7 @@ This project is licensed under the MIT License - see the [LICENSE](LICENSE) file
 - Improved reflection safety
 - Fixed COUNT query issues with table aliasing
 - Better pointer handling throughout the codebase
+- **Comprehensive Test Coverage**: Added standalone CRUD tests for both ResolveSpec and RestHeadSpec
 
 ### v2.0
 

pkg/common/adapters/database/bun.go

@@ -215,6 +215,40 @@ func (b *BunSelectQuery) Preload(relation string, conditions ...interface{}) com
 	return b
 }
 
+func (b *BunSelectQuery) PreloadRelation(relation string, apply ...func(common.SelectQuery) common.SelectQuery) common.SelectQuery {
+	b.query = b.query.Relation(relation, func(sq *bun.SelectQuery) *bun.SelectQuery {
+		if len(apply) == 0 {
+			return sq
+		}
+
+		// Wrap the incoming *bun.SelectQuery in our adapter
+		wrapper := &BunSelectQuery{
+			query: sq,
+			db:    b.db,
+		}
+
+		// Start with the interface value (not pointer)
+		current := common.SelectQuery(wrapper)
+
+		// Apply each function in sequence
+		for _, fn := range apply {
+			if fn != nil {
+				// Pass &current (pointer to interface variable), fn modifies and returns new interface value
+				modified := fn(current)
+				current = modified
+			}
+		}
+
+		// Extract the final *bun.SelectQuery
+		if finalBun, ok := current.(*BunSelectQuery); ok {
+			return finalBun.query
+		}
+
+		return sq // fallback
+	})
+	return b
+}
+
 func (b *BunSelectQuery) Order(order string) common.SelectQuery {
 	b.query = b.query.Order(order)
 	return b

pkg/common/adapters/database/gorm.go

@@ -197,6 +197,36 @@ func (g *GormSelectQuery) Preload(relation string, conditions ...interface{}) co
 	return g
 }
 
+func (g *GormSelectQuery) PreloadRelation(relation string, apply ...func(common.SelectQuery) common.SelectQuery) common.SelectQuery {
+	g.db = g.db.Preload(relation, func(db *gorm.DB) *gorm.DB {
+		if len(apply) == 0 {
+			return db
+		}
+
+		wrapper := &GormSelectQuery{
+			db: db,
+		}
+
+		current := common.SelectQuery(wrapper)
+
+		for _, fn := range apply {
+			if fn != nil {
+
+				modified := fn(current)
+				current = modified
+			}
+		}
+
+		if finalBun, ok := current.(*GormSelectQuery); ok {
+			return finalBun.db
+		}
+
+		return db // fallback
+	})
+
+	return g
+}
+
 func (g *GormSelectQuery) Order(order string) common.SelectQuery {
 	g.db = g.db.Order(order)
 	return g

pkg/common/interfaces.go

@@ -32,6 +32,7 @@ type SelectQuery interface {
 	Join(query string, args ...interface{}) SelectQuery
 	LeftJoin(query string, args ...interface{}) SelectQuery
 	Preload(relation string, conditions ...interface{}) SelectQuery
+	PreloadRelation(relation string, apply ...func(SelectQuery) SelectQuery) SelectQuery
 	Order(order string) SelectQuery
 	Limit(n int) SelectQuery
 	Offset(n int) SelectQuery

pkg/common/recursive_crud.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/bitechdev/ResolveSpec/pkg/logger"
+	"github.com/bitechdev/ResolveSpec/pkg/reflection"
 )
 
 // CRUDRequestProvider interface for models that provide CRUD request strings
@@ -248,7 +249,7 @@ func (p *NestedCUDProcessor) processUpdate(
 
 	logger.Debug("Updating %s with ID %v, data: %+v", tableName, id, data)
 
-	query := p.db.NewUpdate().Table(tableName).SetMap(data).Where("id = ?", id)
+	query := p.db.NewUpdate().Table(tableName).SetMap(data).Where(fmt.Sprintf("%s = ?", QuoteIdent(reflection.GetPrimaryKeyName(tableName))), id)
 
 	result, err := query.Exec(ctx)
 	if err != nil {
@@ -268,7 +269,7 @@ func (p *NestedCUDProcessor) processDelete(ctx context.Context, tableName string
 
 	logger.Debug("Deleting from %s with ID %v", tableName, id)
 
-	query := p.db.NewDelete().Table(tableName).Where("id = ?", id)
+	query := p.db.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", QuoteIdent(reflection.GetPrimaryKeyName(tableName))), id)
 
 	result, err := query.Exec(ctx)
 	if err != nil {

pkg/common/types.go

@@ -35,7 +35,9 @@ type PreloadOption struct {
 	Relation    string         `json:"relation"`
 	Columns     []string       `json:"columns"`
 	OmitColumns []string       `json:"omit_columns"`
+	Sort        []SortOption   `json:"sort"`
 	Filters     []FilterOption `json:"filters"`
+	Where       string         `json:"where"`
 	Limit       *int           `json:"limit"`
 	Offset      *int           `json:"offset"`
 	Updatable   *bool          `json:"updateable"` // if true, the relation can be updated

pkg/common/validation.go

@@ -183,7 +183,8 @@ func (v *ColumnValidator) ValidateRequestOptions(options RequestOptions) error {
 	}
 
 	// Validate Preload columns (if specified)
-	for _, preload := range options.Preload {
+	for idx := range options.Preload {
+		preload := options.Preload[idx]
 		// Note: We don't validate the relation name itself, as it's a relationship
 		// Only validate columns if specified for the preload
 		if err := v.ValidateColumns(preload.Columns); err != nil {
@@ -239,7 +240,8 @@ func (v *ColumnValidator) FilterRequestOptions(options RequestOptions) RequestOp
 
 	// Filter Preload columns
 	validPreloads := make([]PreloadOption, 0, len(options.Preload))
-	for _, preload := range options.Preload {
+	for idx := range options.Preload {
+		preload := options.Preload[idx]
 		filteredPreload := preload
 		filteredPreload.Columns = v.FilterValidColumns(preload.Columns)
 		filteredPreload.OmitColumns = v.FilterValidColumns(preload.OmitColumns)
@@ -270,3 +272,11 @@ func (v *ColumnValidator) GetValidColumns() []string {
 	}
 	return columns
 }
+
+func QuoteIdent(qualifier string) string {
+	return `"` + strings.ReplaceAll(qualifier, `"`, `""`) + `"`
+}
+
+func QuoteLiteral(value string) string {
+	return `'` + strings.ReplaceAll(value, `'`, `''`) + `'`
+}

pkg/reflection/helpers.go

@@ -1,9 +1,15 @@
-package common
+package reflection
 
 import "reflect"
 
 func Len(v any) int {
 	val := reflect.ValueOf(v)
+	valKind := val.Kind()
+
+	if valKind == reflect.Ptr {
+		val = val.Elem()
+	}
+
 	switch val.Kind() {
 	case reflect.Slice, reflect.Array, reflect.Map, reflect.String, reflect.Chan:
 		return val.Len()

pkg/reflection/model_utils.go

@@ -4,15 +4,31 @@ import (
 	"reflect"
 	"strings"
 
-	"github.com/bitechdev/ResolveSpec/pkg/common"
+	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
 )
 
+type PrimaryKeyNameProvider interface {
+	GetIDName() string
+}
+
 // GetPrimaryKeyName extracts the primary key column name from a model
 // It first checks if the model implements PrimaryKeyNameProvider (GetIDName method)
 // Falls back to reflection to find bun:",pk" tag, then gorm:"primaryKey" tag
 func GetPrimaryKeyName(model any) string {
+	if reflect.TypeOf(model) == nil {
+		return ""
+	}
+	// If we are given a string model name, look up the model
+	if reflect.TypeOf(model).Kind() == reflect.String {
+		name := model.(string)
+		m, err := modelregistry.GetModelByName(name)
+		if err == nil {
+			model = m
+		}
+	}
+
 	// Check if model implements PrimaryKeyNameProvider
-	if provider, ok := model.(common.PrimaryKeyNameProvider); ok {
+	if provider, ok := model.(PrimaryKeyNameProvider); ok {
 		return provider.GetIDName()
 	}
 
@@ -22,7 +38,11 @@ func GetPrimaryKeyName(model any) string {
 	}
 
 	// Fall back to GORM tag
-	return getPrimaryKeyFromReflection(model, "gorm")
+	if pkName := getPrimaryKeyFromReflection(model, "gorm"); pkName != "" {
+		return pkName
+	}
+
+	return ""
 }
 
 // GetModelColumns extracts all column names from a model using reflection

pkg/resolvespec/handler.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/bitechdev/ResolveSpec/pkg/common"
 	"github.com/bitechdev/ResolveSpec/pkg/logger"
+	"github.com/bitechdev/ResolveSpec/pkg/reflection"
 )
 
 // Handler handles API requests using database and model abstractions
@@ -199,7 +200,7 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 	if len(options.ComputedColumns) > 0 {
 		for _, cu := range options.ComputedColumns {
 			logger.Debug("Applying computed column: %s", cu.Name)
-			query = query.ColumnExpr("(?) AS "+cu.Name, cu.Expression)
+			query = query.ColumnExpr(fmt.Sprintf("(%s) AS %s", cu.Expression, cu.Name))
 		}
 	}
 
@@ -249,7 +250,8 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 		logger.Debug("Querying single record with ID: %s", id)
 		// For single record, create a new pointer to the struct type
 		singleResult := reflect.New(modelType).Interface()
-		query = query.Where("id = ?", id)
+
+		query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(singleResult))), id)
 		if err := query.Scan(ctx, singleResult); err != nil {
 			logger.Error("Error querying record: %v", err)
 			h.sendError(w, http.StatusInternalServerError, "query_error", "Error executing query", err)
@@ -521,15 +523,15 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, url
 		// Apply conditions
 		if urlID != "" {
 			logger.Debug("Updating by URL ID: %s", urlID)
-			query = query.Where("id = ?", urlID)
+			query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), urlID)
 		} else if reqID != nil {
 			switch id := reqID.(type) {
 			case string:
 				logger.Debug("Updating by request ID: %s", id)
-				query = query.Where("id = ?", id)
+				query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), id)
 			case []string:
 				logger.Debug("Updating by multiple IDs: %v", id)
-				query = query.Where("id IN (?)", id)
+				query = query.Where(fmt.Sprintf("%s IN (?)", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), id)
 			}
 		}
 
@@ -593,7 +595,8 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, url
 		err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
 			for _, item := range updates {
 				if itemID, ok := item["id"]; ok {
-					txQuery := tx.NewUpdate().Table(tableName).SetMap(item).Where("id = ?", itemID)
+
+					txQuery := tx.NewUpdate().Table(tableName).SetMap(item).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 					if _, err := txQuery.Exec(ctx); err != nil {
 						return err
 					}
@@ -659,7 +662,8 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, url
 			for _, item := range updates {
 				if itemMap, ok := item.(map[string]interface{}); ok {
 					if itemID, ok := itemMap["id"]; ok {
-						txQuery := tx.NewUpdate().Table(tableName).SetMap(itemMap).Where("id = ?", itemID)
+
+						txQuery := tx.NewUpdate().Table(tableName).SetMap(itemMap).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 						if _, err := txQuery.Exec(ctx); err != nil {
 							return err
 						}
@@ -695,6 +699,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 	schema := GetSchema(ctx)
 	entity := GetEntity(ctx)
 	tableName := GetTableName(ctx)
+	model := GetModel(ctx)
 
 	logger.Info("Deleting records from %s.%s", schema, entity)
 
@@ -706,7 +711,8 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 			logger.Info("Batch delete with %d IDs ([]string)", len(v))
 			err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
 				for _, itemID := range v {
-					query := tx.NewDelete().Table(tableName).Where("id = ?", itemID)
+
+					query := tx.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 					if _, err := query.Exec(ctx); err != nil {
 						return fmt.Errorf("failed to delete record %s: %w", itemID, err)
 					}
@@ -745,7 +751,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 						continue // Skip items without ID
 					}
 
-					query := tx.NewDelete().Table(tableName).Where("id = ?", itemID)
+					query := tx.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 					result, err := query.Exec(ctx)
 					if err != nil {
 						return fmt.Errorf("failed to delete record %v: %w", itemID, err)
@@ -770,7 +776,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 			err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
 				for _, item := range v {
 					if itemID, ok := item["id"]; ok && itemID != nil {
-						query := tx.NewDelete().Table(tableName).Where("id = ?", itemID)
+						query := tx.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 						result, err := query.Exec(ctx)
 						if err != nil {
 							return fmt.Errorf("failed to delete record %v: %w", itemID, err)
@@ -804,7 +810,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 		return
 	}
 
-	query := h.db.NewDelete().Table(tableName).Where("id = ?", id)
+	query := h.db.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), id)
 
 	result, err := query.Exec(ctx)
 	if err != nil {
@@ -1113,7 +1119,8 @@ func (h *Handler) applyPreloads(model interface{}, query common.SelectQuery, pre
 		return query
 	}
 
-	for _, preload := range preloads {
+	for idx := range preloads {
+		preload := preloads[idx]
 		logger.Debug("Processing preload for relation: %s", preload.Relation)
 		relInfo := h.getRelationshipInfo(modelType, preload.Relation)
 		if relInfo == nil {
@@ -1128,7 +1135,75 @@ func (h *Handler) applyPreloads(model interface{}, query common.SelectQuery, pre
 		// For now, we'll preload without conditions
 		// TODO: Implement column selection and filtering for preloads
 		// This requires a more sophisticated approach with callbacks or query builders
-		query = query.Preload(relationFieldName)
+		// Apply preloading
+
+		logger.Debug("Applying preload: %s", relationFieldName)
+		query = query.PreloadRelation(relationFieldName, func(sq common.SelectQuery) common.SelectQuery {
+			if len(preload.OmitColumns) > 0 {
+				allCols := reflection.GetModelColumns(model)
+				// Remove omitted columns
+				preload.Columns = []string{}
+				for _, col := range allCols {
+					addCols := true
+					for _, omitCol := range preload.OmitColumns {
+						if col == omitCol {
+							addCols = false
+							break
+						}
+					}
+					if addCols {
+						preload.Columns = append(preload.Columns, col)
+					}
+				}
+			}
+
+			if len(preload.Columns) > 0 {
+				// Ensure foreign key is included in column selection for GORM to establish the relationship
+				columns := make([]string, len(preload.Columns))
+				copy(columns, preload.Columns)
+
+				// Add foreign key if not already present
+				if relInfo.foreignKey != "" {
+					// Convert struct field name (e.g., DepartmentID) to snake_case (e.g., department_id)
+					foreignKeyColumn := toSnakeCase(relInfo.foreignKey)
+
+					hasForeignKey := false
+					for _, col := range columns {
+						if col == foreignKeyColumn || col == relInfo.foreignKey {
+							hasForeignKey = true
+							break
+						}
+					}
+					if !hasForeignKey {
+						columns = append(columns, foreignKeyColumn)
+					}
+				}
+
+				sq = sq.Column(columns...)
+			}
+
+			if len(preload.Filters) > 0 {
+				for _, filter := range preload.Filters {
+					sq = h.applyFilter(sq, filter)
+				}
+			}
+			if len(preload.Sort) > 0 {
+				for _, sort := range preload.Sort {
+					sq = sq.Order(fmt.Sprintf("%s %s", sort.Column, sort.Direction))
+				}
+			}
+
+			if len(preload.Where) > 0 {
+				sq = sq.Where(preload.Where)
+			}
+
+			if preload.Limit != nil && *preload.Limit > 0 {
+				sq = sq.Limit(*preload.Limit)
+			}
+
+			return sq
+		})
+
 		logger.Debug("Applied Preload for relation: %s (field: %s)", preload.Relation, relationFieldName)
 	}
 
@@ -1186,3 +1261,28 @@ func (h *Handler) extractTagValue(tag, key string) string {
 	}
 	return ""
 }
+
+// toSnakeCase converts a PascalCase or camelCase string to snake_case
+func toSnakeCase(s string) string {
+	var result strings.Builder
+	runes := []rune(s)
+
+	for i := 0; i < len(runes); i++ {
+		r := runes[i]
+
+		if i > 0 && r >= 'A' && r <= 'Z' {
+			// Check if previous character is lowercase or if next character is lowercase
+			prevIsLower := runes[i-1] >= 'a' && runes[i-1] <= 'z'
+			nextIsLower := i+1 < len(runes) && runes[i+1] >= 'a' && runes[i+1] <= 'z'
+
+			// Add underscore if this is the start of a new word
+			// (previous was lowercase OR this is followed by lowercase)
+			if prevIsLower || nextIsLower {
+				result.WriteByte('_')
+			}
+		}
+
+		result.WriteRune(r)
+	}
+	return strings.ToLower(result.String())
+}

pkg/restheadspec/handler.go

@@ -257,14 +257,28 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 	if len(options.ComputedQL) > 0 {
 		for colName, colExpr := range options.ComputedQL {
 			logger.Debug("Applying computed column: %s", colName)
-			query = query.ColumnExpr("(?) AS "+colName, colExpr)
+			query = query.ColumnExpr(fmt.Sprintf("(%s) AS %s", colExpr, colName))
+			for colIndex := range options.Columns {
+				if options.Columns[colIndex] == colName {
+					// Remove the computed column from the selected columns to avoid duplication
+					options.Columns = append(options.Columns[:colIndex], options.Columns[colIndex+1:]...)
+					break
+				}
+			}
 		}
 	}
 
 	if len(options.ComputedColumns) > 0 {
 		for _, cu := range options.ComputedColumns {
 			logger.Debug("Applying computed column: %s", cu.Name)
-			query = query.ColumnExpr("(?) AS "+cu.Name, cu.Expression)
+			query = query.ColumnExpr(fmt.Sprintf("(%s) AS %s", cu.Expression, cu.Name))
+			for colIndex := range options.Columns {
+				if options.Columns[colIndex] == cu.Name {
+					// Remove the computed column from the selected columns to avoid duplication
+					options.Columns = append(options.Columns[:colIndex], options.Columns[colIndex+1:]...)
+					break
+				}
+			}
 		}
 	}
 
@@ -274,18 +288,95 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 		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)
+	// Apply expand (Just expand to Preload for now)
 	for _, expand := range options.Expand {
 		logger.Debug("Applying expand: %s", expand.Relation)
+		sorts := make([]common.SortOption, 0)
+		for _, s := range strings.Split(expand.Sort, ",") {
+			if s == "" {
+				continue
+			}
+			dir := "ASC"
+			if strings.HasPrefix(s, "-") || strings.HasSuffix(strings.ToUpper(s), " DESC") {
+				dir = "DESC"
+				s = strings.TrimPrefix(s, "-")
+				s = strings.TrimSuffix(strings.ToLower(s), " desc")
+			}
+			sorts = append(sorts, common.SortOption{
+				Column: s, Direction: dir,
+			})
+		}
 		// Note: Expand would require JOIN implementation
 		// For now, we'll use Preload as a fallback
-		query = query.Preload(expand.Relation)
+		// query = query.Preload(expand.Relation)
+		if options.Preload == nil {
+			options.Preload = make([]common.PreloadOption, 0)
+		}
+		skip := false
+		for idx := range options.Preload {
+			if options.Preload[idx].Relation == expand.Relation {
+				skip = true
+				continue
+			}
+		}
+		if !skip {
+			options.Preload = append(options.Preload, common.PreloadOption{
+				Relation: expand.Relation,
+				Columns:  expand.Columns,
+				Sort:     sorts,
+				Where:    expand.Where,
+			})
+		}
+	}
+
+	// Apply preloading
+	for idx := range options.Preload {
+		preload := options.Preload[idx]
+		logger.Debug("Applying preload: %s", preload.Relation)
+		query = query.PreloadRelation(preload.Relation, func(sq common.SelectQuery) common.SelectQuery {
+			if len(preload.OmitColumns) > 0 {
+				allCols := reflection.GetModelColumns(model)
+				// Remove omitted columns
+				preload.Columns = []string{}
+				for _, col := range allCols {
+					addCols := true
+					for _, omitCol := range preload.OmitColumns {
+						if col == omitCol {
+							addCols = false
+							break
+						}
+					}
+					if addCols {
+						preload.Columns = append(preload.Columns, col)
+					}
+				}
+			}
+
+			if len(preload.Columns) > 0 {
+				sq = sq.Column(preload.Columns...)
+			}
+
+			if len(preload.Filters) > 0 {
+				for _, filter := range preload.Filters {
+					sq = h.applyFilter(sq, filter, "", false, "AND")
+				}
+			}
+			if len(preload.Sort) > 0 {
+				for _, sort := range preload.Sort {
+					sq = sq.Order(fmt.Sprintf("%s %s", sort.Column, sort.Direction))
+				}
+			}
+
+			if len(preload.Where) > 0 {
+				sq = sq.Where(preload.Where)
+			}
+
+			if preload.Limit != nil && *preload.Limit > 0 {
+				sq = sq.Limit(*preload.Limit)
+			}
+
+			return sq
+		})
 	}
 
 	// Apply DISTINCT if requested
@@ -326,8 +417,10 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 
 	// If ID is provided, filter by ID
 	if id != "" {
-		logger.Debug("Filtering by ID: %s", id)
-		query = query.Where("id = ?", id)
+		pkName := reflection.GetPrimaryKeyName(model)
+		logger.Debug("Filtering by ID=%s: %s", pkName, id)
+
+		query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(pkName)), id)
 	}
 
 	// Apply sorting
@@ -433,7 +526,7 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 
 	metadata := &common.Metadata{
 		Total:    int64(total),
-		Count:    int64(common.Len(modelPtr)),
+		Count:    int64(reflection.Len(modelPtr)),
 		Filtered: int64(total),
 		Limit:    limit,
 		Offset:   offset,
@@ -794,13 +887,13 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id
 	}
 
 	query := h.db.NewUpdate().Table(tableName).SetMap(dataMap)
-
+	pkName := reflection.GetPrimaryKeyName(model)
 	// Apply ID filter
 	switch {
 	case id != "":
-		query = query.Where("id = ?", id)
+		query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(pkName)), id)
 	case idPtr != nil:
-		query = query.Where("id = ?", *idPtr)
+		query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(pkName)), *idPtr)
 	default:
 		h.sendError(w, http.StatusBadRequest, "missing_id", "ID is required for update", nil)
 		return
@@ -883,7 +976,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 						continue
 					}
 
-					query := tx.NewDelete().Table(tableName).Where("id = ?", itemID)
+					query := tx.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 
 					result, err := query.Exec(ctx)
 					if err != nil {
@@ -950,7 +1043,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 						continue
 					}
 
-					query := tx.NewDelete().Table(tableName).Where("id = ?", itemID)
+					query := tx.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 					result, err := query.Exec(ctx)
 					if err != nil {
 						return fmt.Errorf("failed to delete record %v: %w", itemID, err)
@@ -1001,7 +1094,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 							continue
 						}
 
-						query := tx.NewDelete().Table(tableName).Where("id = ?", itemID)
+						query := tx.NewDelete().Table(tableName).Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), itemID)
 						result, err := query.Exec(ctx)
 						if err != nil {
 							return fmt.Errorf("failed to delete record %v: %w", itemID, err)
@@ -1061,7 +1154,7 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 		return
 	}
 
-	query = query.Where("id = ?", id)
+	query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(reflection.GetPrimaryKeyName(model))), id)
 
 	// Execute BeforeScan hooks - pass query chain so hooks can modify it
 	hookCtx.Query = query
@@ -1441,6 +1534,9 @@ func (h *Handler) FetchRowNumber(ctx context.Context, tableName string, pkName s
 	if len(options.Sort) > 0 {
 		sortParts := make([]string, 0, len(options.Sort))
 		for _, sort := range options.Sort {
+			if sort.Column == "" {
+				continue
+			}
 			direction := "ASC"
 			if strings.EqualFold(sort.Direction, "desc") {
 				direction = "DESC"

pkg/restheadspec/headers.go

@@ -146,7 +146,12 @@ func (h *Handler) parseOptionsFromHeaders(r common.Request) ExtendedRequestOptio
 
 		// Joins & Relations
 		case strings.HasPrefix(normalizedKey, "x-preload"):
-			h.parsePreload(&options, decodedValue)
+			if strings.HasSuffix(normalizedKey, "-where") {
+				continue
+			}
+			whereClaude := headers[fmt.Sprintf("%s-where", key)]
+			h.parsePreload(&options, decodedValue, decodeHeaderValue(whereClaude))
+
 		case strings.HasPrefix(normalizedKey, "x-expand"):
 			h.parseExpand(&options, decodedValue)
 		case strings.HasPrefix(normalizedKey, "x-custom-sql-join"):
@@ -341,7 +346,15 @@ func (h *Handler) mapSearchOperator(colName, operator, value string) common.Filt
 
 // parsePreload parses x-preload header
 // Format: RelationName:field1,field2 or RelationName or multiple separated by |
-func (h *Handler) parsePreload(options *ExtendedRequestOptions, value string) {
+func (h *Handler) parsePreload(options *ExtendedRequestOptions, values ...string) {
+	if len(values) == 0 {
+		return
+	}
+	value := values[0]
+	whereClause := ""
+	if len(values) > 1 {
+		whereClause = values[1]
+	}
 	if value == "" {
 		return
 	}
@@ -358,6 +371,7 @@ func (h *Handler) parsePreload(options *ExtendedRequestOptions, value string) {
 		parts := strings.SplitN(preloadStr, ":", 2)
 		preload := common.PreloadOption{
 			Relation: strings.TrimSpace(parts[0]),
+			Where:    whereClause,
 		}
 
 		if len(parts) == 2 {