Huge preload chains causing errors, workaround to do seperate selects.

pkg/common/adapters/database/bun.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"reflect"
 	"strings"
 
 	"github.com/uptrace/bun"
@@ -99,12 +100,20 @@ func (b *BunAdapter) RunInTransaction(ctx context.Context, fn func(common.Databa
 
 // BunSelectQuery implements SelectQuery for Bun
 type BunSelectQuery struct {
-	query      *bun.SelectQuery
+	query            *bun.SelectQuery
-	db         bun.IDB // Store DB connection for count queries
+	db               bun.IDB // Store DB connection for count queries
-	hasModel   bool    // Track if Model() was called
+	hasModel         bool    // Track if Model() was called
-	schema     string  // Separated schema name
+	schema           string  // Separated schema name
-	tableName  string  // Just the table name, without schema
+	tableName        string  // Just the table name, without schema
-	tableAlias string
+	tableAlias       string
+	deferredPreloads []deferredPreload // Preloads to execute as separate queries
+}
+
+// deferredPreload represents a preload that will be executed as a separate query
+// to avoid PostgreSQL identifier length limits
+type deferredPreload struct {
+	relation string
+	apply    []func(common.SelectQuery) common.SelectQuery
 }
 
 func (b *BunSelectQuery) Model(model interface{}) common.SelectQuery {
@@ -233,7 +242,92 @@ func (b *BunSelectQuery) Preload(relation string, conditions ...interface{}) com
 	return b
 }
 
+// // shortenAliasForPostgres shortens a table/relation alias if it would exceed PostgreSQL's 63-char limit
+// // when combined with typical column names
+// func shortenAliasForPostgres(relationPath string) (string, bool) {
+// 	// Convert relation path to the alias format Bun uses: dots become double underscores
+// 	// Also convert to lowercase and use snake_case as Bun does
+// 	parts := strings.Split(relationPath, ".")
+// 	alias := strings.ToLower(strings.Join(parts, "__"))
+
+// 	// PostgreSQL truncates identifiers to 63 chars
+// 	// If the alias + typical column name would exceed this, we need to shorten
+// 	// Reserve at least 30 chars for column names (e.g., "__rid_mastertype_hubtype")
+// 	const maxAliasLength = 30
+
+// 	if len(alias) > maxAliasLength {
+// 		// Create a shortened alias using a hash of the original
+// 		hash := md5.Sum([]byte(alias))
+// 		hashStr := hex.EncodeToString(hash[:])[:8]
+
+// 		// Keep first few chars of original for readability + hash
+// 		prefixLen := maxAliasLength - 9 // 9 = 1 underscore + 8 hash chars
+// 		if prefixLen > len(alias) {
+// 			prefixLen = len(alias)
+// 		}
+
+// 		shortened := alias[:prefixLen] + "_" + hashStr
+// 		logger.Debug("Shortened alias '%s' (%d chars) to '%s' (%d chars) to avoid PostgreSQL 63-char limit",
+// 			alias, len(alias), shortened, len(shortened))
+// 		return shortened, true
+// 	}
+
+// 	return alias, false
+// }
+
+// // estimateColumnAliasLength estimates the length of a column alias in a nested preload
+// // Bun creates aliases like: relationChain__columnName
+// func estimateColumnAliasLength(relationPath string, columnName string) int {
+// 	relationParts := strings.Split(relationPath, ".")
+// 	aliasChain := strings.ToLower(strings.Join(relationParts, "__"))
+// 	// Bun adds "__" between alias and column name
+// 	return len(aliasChain) + 2 + len(columnName)
+// }
+
 func (b *BunSelectQuery) PreloadRelation(relation string, apply ...func(common.SelectQuery) common.SelectQuery) common.SelectQuery {
+	// Check if this relation chain would create problematic long aliases
+	relationParts := strings.Split(relation, ".")
+	aliasChain := strings.ToLower(strings.Join(relationParts, "__"))
+
+	// PostgreSQL's identifier limit is 63 characters
+	const postgresIdentifierLimit = 63
+	const safeAliasLimit = 35 // Leave room for column names
+
+	// If the alias chain is too long, defer this preload to be executed as a separate query
+	if len(aliasChain) > safeAliasLimit {
+		logger.Info("Preload relation '%s' creates long alias chain '%s' (%d chars). "+
+			"Using separate query to avoid PostgreSQL %d-char identifier limit.",
+			relation, aliasChain, len(aliasChain), postgresIdentifierLimit)
+
+		// For nested preloads (e.g., "Parent.Child"), split into separate preloads
+		// This avoids the long concatenated alias
+		if len(relationParts) > 1 {
+			// Load first level normally: "Parent"
+			firstLevel := relationParts[0]
+			remainingPath := strings.Join(relationParts[1:], ".")
+
+			logger.Info("Splitting nested preload: loading '%s' first, then '%s' separately",
+				firstLevel, remainingPath)
+
+			// Apply the first level preload normally
+			b.query = b.query.Relation(firstLevel)
+
+			// Store the remaining nested preload to be executed after the main query
+			b.deferredPreloads = append(b.deferredPreloads, deferredPreload{
+				relation: relation,
+				apply:    apply,
+			})
+
+			return b
+		}
+
+		// Single level but still too long - just warn and continue
+		logger.Warn("Single-level preload '%s' has a very long name (%d chars). "+
+			"Consider renaming the field to avoid potential issues.",
+			relation, len(aliasChain))
+	}
+
+	// Normal preload handling
 	b.query = b.query.Relation(relation, func(sq *bun.SelectQuery) *bun.SelectQuery {
 		defer func() {
 			if r := recover(); r != nil {
@@ -309,7 +403,23 @@ func (b *BunSelectQuery) Scan(ctx context.Context, dest interface{}) (err error)
 	if dest == nil {
 		return fmt.Errorf("destination cannot be nil")
 	}
-	return b.query.Scan(ctx, dest)
+
+	// Execute the main query first
+	err = b.query.Scan(ctx, dest)
+	if err != nil {
+		return err
+	}
+
+	// Execute any deferred preloads
+	if len(b.deferredPreloads) > 0 {
+		err = b.executeDeferredPreloads(ctx, dest)
+		if err != nil {
+			logger.Warn("Failed to execute deferred preloads: %v", err)
+			// Don't fail the whole query, just log the warning
+		}
+	}
+
+	return nil
 }
 
 func (b *BunSelectQuery) ScanModel(ctx context.Context) (err error) {
@@ -322,7 +432,132 @@ func (b *BunSelectQuery) ScanModel(ctx context.Context) (err error) {
 		return fmt.Errorf("model is nil")
 	}
 
-	return b.query.Scan(ctx)
+	// Execute the main query first
+	err = b.query.Scan(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Execute any deferred preloads
+	if len(b.deferredPreloads) > 0 {
+		model := b.query.GetModel()
+		err = b.executeDeferredPreloads(ctx, model.Value())
+		if err != nil {
+			logger.Warn("Failed to execute deferred preloads: %v", err)
+			// Don't fail the whole query, just log the warning
+		}
+	}
+
+	return nil
+}
+
+// executeDeferredPreloads executes preloads that were deferred to avoid PostgreSQL identifier length limits
+func (b *BunSelectQuery) executeDeferredPreloads(ctx context.Context, dest interface{}) error {
+	if len(b.deferredPreloads) == 0 {
+		return nil
+	}
+
+	for _, dp := range b.deferredPreloads {
+		err := b.executeSingleDeferredPreload(ctx, dest, dp)
+		if err != nil {
+			return fmt.Errorf("failed to execute deferred preload '%s': %w", dp.relation, err)
+		}
+	}
+
+	return nil
+}
+
+// executeSingleDeferredPreload executes a single deferred preload
+// For a relation like "Parent.Child", it:
+// 1. Finds all loaded Parent records in dest
+// 2. Loads Child records for those Parents using a separate query (loading only "Child", not "Parent.Child")
+// 3. Bun automatically assigns the Child records to the appropriate Parent.Child field
+func (b *BunSelectQuery) executeSingleDeferredPreload(ctx context.Context, dest interface{}, dp deferredPreload) error {
+	relationParts := strings.Split(dp.relation, ".")
+	if len(relationParts) < 2 {
+		return fmt.Errorf("deferred preload must be nested (e.g., 'Parent.Child'), got: %s", dp.relation)
+	}
+
+	// The parent relation that was already loaded
+	parentRelation := relationParts[0]
+	// The child relation we need to load
+	childRelation := strings.Join(relationParts[1:], ".")
+
+	logger.Debug("Executing deferred preload: loading '%s' on already-loaded '%s'", childRelation, parentRelation)
+
+	// Use reflection to access the parent relation field(s) in the loaded records
+	// Then load the child relation for those parent records
+	destValue := reflect.ValueOf(dest)
+	if destValue.Kind() == reflect.Ptr {
+		destValue = destValue.Elem()
+	}
+
+	// Handle both slice and single record
+	if destValue.Kind() == reflect.Slice {
+		// Iterate through each record in the slice
+		for i := 0; i < destValue.Len(); i++ {
+			record := destValue.Index(i)
+			if err := b.loadChildRelationForRecord(ctx, record, parentRelation, childRelation, dp.apply); err != nil {
+				logger.Warn("Failed to load child relation '%s' for record %d: %v", childRelation, i, err)
+				// Continue with other records
+			}
+		}
+	} else {
+		// Single record
+		if err := b.loadChildRelationForRecord(ctx, destValue, parentRelation, childRelation, dp.apply); err != nil {
+			return fmt.Errorf("failed to load child relation '%s': %w", childRelation, err)
+		}
+	}
+
+	return nil
+}
+
+// loadChildRelationForRecord loads a child relation for a single parent record
+func (b *BunSelectQuery) loadChildRelationForRecord(ctx context.Context, record reflect.Value, parentRelation, childRelation string, apply []func(common.SelectQuery) common.SelectQuery) error {
+	// Ensure we're working with the actual struct value, not a pointer
+	if record.Kind() == reflect.Ptr {
+		record = record.Elem()
+	}
+
+	// Get the parent relation field
+	parentField := record.FieldByName(parentRelation)
+	if !parentField.IsValid() {
+		// Parent relation field doesn't exist
+		logger.Debug("Parent relation field '%s' not found in record", parentRelation)
+		return nil
+	}
+
+	// Check if the parent field is nil (for pointer fields)
+	if parentField.Kind() == reflect.Ptr && parentField.IsNil() {
+		// Parent relation not loaded or nil, skip
+		logger.Debug("Parent relation field '%s' is nil, skipping child preload", parentRelation)
+		return nil
+	}
+
+	// Get the interface value to pass to Bun
+	parentValue := parentField.Interface()
+
+	// Load the child relation on the parent record
+	// This uses a shorter alias since we're only loading "Child", not "Parent.Child"
+	return b.db.NewSelect().
+		Model(parentValue).
+		Relation(childRelation, func(sq *bun.SelectQuery) *bun.SelectQuery {
+			// Apply any custom query modifications
+			if len(apply) > 0 {
+				wrapper := &BunSelectQuery{query: sq, db: b.db}
+				current := common.SelectQuery(wrapper)
+				for _, fn := range apply {
+					if fn != nil {
+						current = fn(current)
+					}
+				}
+				if finalBun, ok := current.(*BunSelectQuery); ok {
+					return finalBun.query
+				}
+			}
+			return sq
+		}).
+		Scan(ctx)
 }
 
 func (b *BunSelectQuery) Count(ctx context.Context) (count int, err error) {

pkg/resolvespec/handler.go

@@ -199,7 +199,9 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 	// Apply column selection
 	if len(options.Columns) > 0 {
 		logger.Debug("Selecting columns: %v", options.Columns)
-		query = query.Column(options.Columns...)
+		for _, col := range options.Columns {
+			query = query.Column(reflection.ExtractSourceColumn(col))
+		}
 	}
 
 	if len(options.ComputedColumns) > 0 {

pkg/restheadspec/handler.go

@@ -213,6 +213,10 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 	tableName := GetTableName(ctx)
 	model := GetModel(ctx)
 
+	if id == "" {
+		options.SingleRecordAsObject = false
+	}
+
 	// Execute BeforeRead hooks
 	hookCtx := &HookContext{
 		Context:   ctx,
@@ -299,7 +303,10 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 	// Apply column selection
 	if len(options.Columns) > 0 {
 		logger.Debug("Selecting columns: %v", options.Columns)
-		query = query.Column(options.Columns...)
+		for _, col := range options.Columns {
+			query = query.Column(reflection.ExtractSourceColumn(col))
+		}
+
 	}
 
 	// Apply expand (Just expand to Preload for now)
@@ -652,7 +659,6 @@ func (h *Handler) applyPreloadWithRecursion(query common.SelectQuery, preload co
 				sq = sq.Order(fmt.Sprintf("%s %s", sort.Column, sort.Direction))
 			}
 		}
-		
 
 		// Apply WHERE clause
 		if len(preload.Where) > 0 {

pkg/restheadspec/headers.go

@@ -162,9 +162,17 @@ func (h *Handler) parseOptionsFromHeaders(r common.Request, model interface{}) E
 		case strings.HasPrefix(key, "x-searchcols"):
 			options.SearchColumns = h.parseCommaSeparated(decodedValue)
 		case strings.HasPrefix(key, "x-custom-sql-w"):
-			options.CustomSQLWhere = decodedValue
+			if options.CustomSQLWhere != "" {
+				options.CustomSQLWhere = fmt.Sprintf("%s AND (%s)", options.CustomSQLWhere, decodedValue)
+			} else {
+				options.CustomSQLWhere = decodedValue
+			}
 		case strings.HasPrefix(key, "x-custom-sql-or"):
-			options.CustomSQLOr = decodedValue
+			if options.CustomSQLOr != "" {
+				options.CustomSQLOr = fmt.Sprintf("%s OR (%s)", options.CustomSQLOr, decodedValue)
+			} else {
+				options.CustomSQLOr = decodedValue
+			}
 
 		// Joins & Relations
 		case strings.HasPrefix(key, "x-preload"):
@@ -226,6 +234,7 @@ func (h *Handler) parseOptionsFromHeaders(r common.Request, model interface{}) E
 		case strings.HasPrefix(key, "x-cql-sel-"):
 			colName := strings.TrimPrefix(key, "x-cql-sel-")
 			options.ComputedQL[colName] = decodedValue
+
 		case strings.HasPrefix(key, "x-distinct"):
 			options.Distinct = strings.EqualFold(decodedValue, "true")
 		case strings.HasPrefix(key, "x-skipcount"):
@@ -267,7 +276,7 @@ func (h *Handler) parseOptionsFromHeaders(r common.Request, model interface{}) E
 		h.resolveRelationNamesInOptions(&options, model)
 	}
 
-	//Always sort according to the primary key if no sorting is specified
+	// Always sort according to the primary key if no sorting is specified
 	if len(options.Sort) == 0 {
 		pkName := reflection.GetPrimaryKeyName(model)
 		options.Sort = []common.SortOption{{Column: pkName, Direction: "ASC"}}
@@ -783,7 +792,7 @@ func (h *Handler) resolveRelationName(model interface{}, nameOrTable string) str
 		field := modelType.Field(i)
 		if field.Name == nameOrTable {
 			// It's already a field name
-			logger.Debug("Input '%s' is a field name", nameOrTable)
+			// logger.Debug("Input '%s' is a field name", nameOrTable)
 			return nameOrTable
 		}
 	}