fix diff round-trip comparison

pkg/diff/diff.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"reflect"
 	"sort"
+	"strconv"
+	"strings"
 
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
 )
@@ -229,11 +231,13 @@ func compareColumns(source, target map[string]*models.Column) *ColumnDiff {
 
 func compareColumnDetails(source, target *models.Column) map[string]any {
 	changes := make(map[string]any)
+	sourceType, sourceLength, sourceDefault := comparableColumn(source)
+	targetType, targetLength, targetDefault := comparableColumn(target)
 
-	if source.Type != target.Type {
+	if sourceType != targetType {
 		changes["type"] = map[string]string{"source": source.Type, "target": target.Type}
 	}
-	if source.Length != target.Length {
+	if sourceLength != targetLength {
 		changes["length"] = map[string]int{"source": source.Length, "target": target.Length}
 	}
 	if source.Precision != target.Precision {
@@ -245,8 +249,8 @@ func compareColumnDetails(source, target *models.Column) map[string]any {
 	if source.NotNull != target.NotNull {
 		changes["not_null"] = map[string]bool{"source": source.NotNull, "target": target.NotNull}
 	}
-	if !reflect.DeepEqual(source.Default, target.Default) {
+	if !reflect.DeepEqual(sourceDefault, targetDefault) {
-		changes["default"] = map[string]any{"source": source.Default, "target": target.Default}
+		changes["default"] = map[string]any{"source": sourceDefault, "target": targetDefault}
 	}
 	if source.AutoIncrement != target.AutoIncrement {
 		changes["auto_increment"] = map[string]bool{"source": source.AutoIncrement, "target": target.AutoIncrement}
@@ -258,6 +262,28 @@ func compareColumnDetails(source, target *models.Column) map[string]any {
 	return changes
 }
 
+// comparableColumn accepts DBML's compact type/default spelling as well as
+// PostgreSQL's normalized fields (for example varchar(255) vs varchar + 255).
+func comparableColumn(column *models.Column) (string, int, any) {
+	typeName := strings.TrimSpace(column.Type)
+	defaultValue := column.Default
+	lower := strings.ToLower(typeName)
+	if i := strings.Index(lower, " default "); i >= 0 {
+		if defaultValue == nil {
+			defaultValue = strings.TrimSpace(typeName[i+len(" default "):])
+		}
+		typeName = strings.TrimSpace(typeName[:i])
+	}
+	length := column.Length
+	if open := strings.LastIndex(typeName, "("); open >= 0 && strings.HasSuffix(typeName, ")") {
+		if parsed, err := strconv.Atoi(strings.TrimSpace(typeName[open+1 : len(typeName)-1])); err == nil && length == 0 {
+			length = parsed
+		}
+		typeName = strings.TrimSpace(typeName[:open])
+	}
+	return strings.ToLower(typeName), length, defaultValue
+}
+
 func compareIndexes(source, target map[string]*models.Index) *IndexDiff {
 	diff := &IndexDiff{
 		Missing:  make([]*models.Index, 0),
@@ -265,34 +291,87 @@ func compareIndexes(source, target map[string]*models.Index) *IndexDiff {
 		Modified: make([]*IndexChange, 0),
 	}
 
-	// Find missing and modified indexes
+	// Match by name first, then by definition. PostgreSQL and DBML can assign
+	// different names to the same index (for example, posts_user_id_title_idx
+	// and uidx_posts_user_id_title), so a name-only comparison reports false
+	// drift after a merge/diff round trip.
+	unmatchedSource := make(map[string]*models.Index, len(source))
+	unmatchedTarget := make(map[string]*models.Index, len(target))
+	for name, index := range source {
+		unmatchedSource[name] = index
+	}
+	for name, index := range target {
+		unmatchedTarget[name] = index
+	}
+
 	for _, name := range sortedKeys(source) {
 		srcIdx := source[name]
-		if tgtIdx, exists := target[name]; !exists {
+		tgtIdx, exists := target[name]
+		if !exists {
+			continue
+		}
+		delete(unmatchedSource, name)
+		delete(unmatchedTarget, name)
+		if changes := compareIndexDetails(srcIdx, tgtIdx); len(changes) > 0 {
+			diff.Modified = append(diff.Modified, &IndexChange{
+				Name:    name,
+				Source:  srcIdx,
+				Target:  tgtIdx,
+				Changes: changes,
+			})
+		}
+	}
+
+	// Pair remaining indexes by their structural identity, independent of the
+	// generated/name field. The sorted iteration makes ambiguous matches
+	// deterministic; duplicate definitions are still represented as separate
+	// indexes by consuming one target at a time.
+	remainingTarget := make(map[string][]*models.Index)
+	for _, name := range sortedKeys(unmatchedTarget) {
+		index := unmatchedTarget[name]
+		key := indexDefinitionKey(index)
+		remainingTarget[key] = append(remainingTarget[key], index)
+	}
+	for _, name := range sortedKeys(unmatchedSource) {
+		srcIdx := unmatchedSource[name]
+		key := indexDefinitionKey(srcIdx)
+		candidates := remainingTarget[key]
+		if len(candidates) == 0 {
 			diff.Missing = append(diff.Missing, srcIdx)
-		} else {
+			continue
-			if changes := compareIndexDetails(srcIdx, tgtIdx); len(changes) > 0 {
+		}
-				diff.Modified = append(diff.Modified, &IndexChange{
+		tgtIdx := candidates[0]
-					Name:    name,
+		remainingTarget[key] = candidates[1:]
-					Source:  srcIdx,
+		if changes := compareIndexDetails(srcIdx, tgtIdx); len(changes) > 0 {
-					Target:  tgtIdx,
+			diff.Modified = append(diff.Modified, &IndexChange{
-					Changes: changes,
+				Name:    srcIdx.Name,
-				})
+				Source:  srcIdx,
-			}
+				Target:  tgtIdx,
+				Changes: changes,
+			})
 		}
 	}
 
-	// Find extra indexes
+	for _, key := range sortedKeys(remainingTarget) {
-	for _, name := range sortedKeys(target) {
+		for _, index := range remainingTarget[key] {
-		tgtIdx := target[name]
+			diff.Extra = append(diff.Extra, index)
-		if _, exists := source[name]; !exists {
-			diff.Extra = append(diff.Extra, tgtIdx)
 		}
 	}
-
 	return diff
 }
 
+func indexDefinitionKey(index *models.Index) string {
+	return fmt.Sprintf("%t:%s:%s", index.Unique, strings.Join(index.Columns, ","), strings.Join(index.Include, ","))
+}
+
+func comparableIndexType(indexType string) string {
+	indexType = strings.ToLower(strings.TrimSpace(indexType))
+	if indexType == "" {
+		return "btree"
+	}
+	return indexType
+}
+
 func compareIndexDetails(source, target *models.Index) map[string]any {
 	changes := make(map[string]any)
 
@@ -302,7 +381,7 @@ func compareIndexDetails(source, target *models.Index) map[string]any {
 	if source.Unique != target.Unique {
 		changes["unique"] = map[string]bool{"source": source.Unique, "target": target.Unique}
 	}
-	if source.Type != target.Type {
+	if comparableIndexType(source.Type) != comparableIndexType(target.Type) {
 		changes["type"] = map[string]string{"source": source.Type, "target": target.Type}
 	}
 	if source.Where != target.Where {
@@ -312,7 +391,26 @@ func compareIndexDetails(source, target *models.Index) map[string]any {
 	return changes
 }
 
+// Compare constraints.
+// Primary-key constraints are excluded: a PK is already represented by the
+// column's IsPrimaryKey flag, which compareColumns already compares. The
+// PostgreSQL reader additionally materialises each PK as a primary_key
+// constraint and a unique btree index; the DBML reader keeps PKs as column
+// flags only. Comparing the constraint maps directly would therefore report
+// every PK as an "extra" constraint and the generated index as an "extra"
+// index on a freshly-applied schema. Filtering them here keeps the round
+// trip stable without losing real PK information.
 func compareConstraints(source, target map[string]*models.Constraint) *ConstraintDiff {
+	filteredSource := filterPrimaryKeyConstraints(source)
+	filteredTarget := filterPrimaryKeyConstraints(target)
+	sourceByKey := make(map[string]*models.Constraint, len(filteredSource))
+	targetByKey := make(map[string]*models.Constraint, len(filteredTarget))
+	for _, constraint := range filteredSource {
+		sourceByKey[constraintCompareKey(constraint)] = constraint
+	}
+	for _, constraint := range filteredTarget {
+		targetByKey[constraintCompareKey(constraint)] = constraint
+	}
 	diff := &ConstraintDiff{
 		Missing:  make([]*models.Constraint, 0),
 		Extra:    make([]*models.Constraint, 0),
@@ -320,9 +418,9 @@ func compareConstraints(source, target map[string]*models.Constraint) *Constrain
 	}
 
 	// Find missing and modified constraints
-	for _, name := range sortedKeys(source) {
+	for _, name := range sortedKeys(sourceByKey) {
-		srcCon := source[name]
+		srcCon := sourceByKey[name]
-		if tgtCon, exists := target[name]; !exists {
+		if tgtCon, exists := targetByKey[name]; !exists {
 			diff.Missing = append(diff.Missing, srcCon)
 		} else {
 			if changes := compareConstraintDetails(srcCon, tgtCon); len(changes) > 0 {
@@ -337,9 +435,9 @@ func compareConstraints(source, target map[string]*models.Constraint) *Constrain
 	}
 
 	// Find extra constraints
-	for _, name := range sortedKeys(target) {
+	for _, name := range sortedKeys(targetByKey) {
-		tgtCon := target[name]
+		tgtCon := targetByKey[name]
-		if _, exists := source[name]; !exists {
+		if _, exists := sourceByKey[name]; !exists {
 			diff.Extra = append(diff.Extra, tgtCon)
 		}
 	}
@@ -347,6 +445,29 @@ func compareConstraints(source, target map[string]*models.Constraint) *Constrain
 	return diff
 }
 
+// filterPrimaryKeyConstraints drops primary_key constraints from a single
+// map. Primary keys are compared by the column IsPrimaryKey flag in
+// compareColumns, so comparing the primary_key constraints here only
+// produces duplicate "extra" entries (every PK is extra on the DBML side).
+// Other constraint types are preserved untouched.
+func filterPrimaryKeyConstraints(m map[string]*models.Constraint) map[string]*models.Constraint {
+	out := make(map[string]*models.Constraint, len(m))
+	for name, c := range m {
+		if c.Type == models.PrimaryKeyConstraint {
+			continue
+		}
+		out[name] = c
+	}
+	return out
+}
+
+func constraintCompareKey(constraint *models.Constraint) string {
+	if constraint.Type != models.ForeignKeyConstraint {
+		return constraint.SQLName()
+	}
+	return fmt.Sprintf("fk:%s:%s:%s:%s:%s:%s", strings.ToLower(constraint.Schema), strings.ToLower(constraint.Table), strings.Join(constraint.Columns, ","), strings.ToLower(constraint.ReferencedSchema), strings.ToLower(constraint.ReferencedTable), strings.Join(constraint.ReferencedColumns, ","))
+}
+
 func compareConstraintDetails(source, target *models.Constraint) map[string]any {
 	changes := make(map[string]any)
 
@@ -362,16 +483,23 @@ func compareConstraintDetails(source, target *models.Constraint) map[string]any
 	if !reflect.DeepEqual(source.ReferencedColumns, target.ReferencedColumns) {
 		changes["referenced_columns"] = map[string][]string{"source": source.ReferencedColumns, "target": target.ReferencedColumns}
 	}
-	if source.OnDelete != target.OnDelete {
+	if normalizeConstraintAction(source.OnDelete) != normalizeConstraintAction(target.OnDelete) {
 		changes["on_delete"] = map[string]string{"source": source.OnDelete, "target": target.OnDelete}
 	}
-	if source.OnUpdate != target.OnUpdate {
+	if normalizeConstraintAction(source.OnUpdate) != normalizeConstraintAction(target.OnUpdate) {
 		changes["on_update"] = map[string]string{"source": source.OnUpdate, "target": target.OnUpdate}
 	}
 
 	return changes
 }
 
+func normalizeConstraintAction(action string) string {
+	if strings.EqualFold(strings.TrimSpace(action), "NO ACTION") {
+		return ""
+	}
+	return strings.ToUpper(strings.TrimSpace(action))
+}
+
 func compareRelationships(source, target map[string]*models.Relationship) *RelationshipDiff {
 	diff := &RelationshipDiff{
 		Missing:  make([]*models.Relationship, 0),

pkg/diff/diff_test.go

@@ -301,6 +301,22 @@ func TestCompareIndexes(t *testing.T) {
 				return len(d.Modified) == 1 && d.Modified[0].Name == "idx_name"
 			},
 		},
+		{
+			name: "equivalent indexes with different generated names",
+			source: map[string]*models.Index{
+				"uidx_posts_user_id_title": {
+					Name: "uidx_posts_user_id_title", Columns: []string{"user_id", "title"}, Unique: true,
+				},
+			},
+			target: map[string]*models.Index{
+				"posts_user_id_title_idx": {
+					Name: "posts_user_id_title_idx", Columns: []string{"user_id", "title"}, Unique: true, Type: "btree",
+				},
+			},
+			want: func(d *IndexDiff) bool {
+				return len(d.Missing) == 0 && len(d.Extra) == 0 && len(d.Modified) == 0
+			},
+		},
 	}
 
 	for _, tt := range tests {

pkg/readers/dbml/reader.go

@@ -571,6 +571,28 @@ func (r *Reader) parseDBML(content string) (*models.Database, error) {
 		}
 	}
 
+	// PostgreSQL readers derive relationships from foreign keys. Do the same
+	// for DBML refs so diffing equivalent schemas compares the same model.
+	for _, schema := range schemaMap {
+		for _, table := range schema.Tables {
+			for _, constraint := range table.Constraints {
+				if constraint.Type != models.ForeignKeyConstraint {
+					continue
+				}
+				name := fmt.Sprintf("%s_to_%s", table.Name, constraint.ReferencedTable)
+				relationship := models.InitRelationship(name, models.OneToMany)
+				relationship.FromTable = table.Name
+				relationship.FromSchema = table.Schema
+				relationship.FromColumns = append([]string(nil), constraint.Columns...)
+				relationship.ToTable = constraint.ReferencedTable
+				relationship.ToSchema = constraint.ReferencedSchema
+				relationship.ToColumns = append([]string(nil), constraint.ReferencedColumns...)
+				relationship.ForeignKey = constraint.Name
+				table.Relationships[name] = relationship
+			}
+		}
+	}
+
 	// Add schemas to database
 	for _, schema := range schemaMap {
 		db.Schemas = append(db.Schemas, schema)

pkg/readers/pgsql/queries.go

@@ -538,8 +538,13 @@ func (r *Reader) queryCheckConstraints(schemaName string) (map[string][]*models.
 		FROM information_schema.table_constraints tc
 		JOIN information_schema.check_constraints cc
 			ON tc.constraint_name = cc.constraint_name
+			AND cc.constraint_schema = tc.table_schema
+		JOIN pg_catalog.pg_constraint pc
+			ON pc.conname = tc.constraint_name
+			AND pc.connamespace = (SELECT oid FROM pg_namespace WHERE nspname = tc.table_schema)
 		WHERE tc.constraint_type = 'CHECK'
 		  AND tc.table_schema = $1
+		AND pc.contype = 'c'
 	`
 
 	rows, err := r.conn.Query(r.ctx, query, schemaName)
@@ -579,7 +584,12 @@ func (r *Reader) queryIndexes(schemaName string) (map[string][]*models.Index, er
 			indexname,
 			indexdef
 		FROM pg_indexes
+		JOIN pg_catalog.pg_class idx ON idx.relname = indexname
+		JOIN pg_catalog.pg_index i ON i.indexrelid = idx.oid
+		JOIN pg_catalog.pg_namespace idx_ns ON idx_ns.oid = idx.relnamespace
 		WHERE schemaname = $1
+		  AND idx_ns.nspname = schemaname
+		  AND NOT i.indisprimary
 		ORDER BY schemaname, tablename, indexname
 	`
 

pkg/readers/pgsql/reader.go

@@ -341,8 +341,10 @@ func (r *Reader) deriveRelationship(table *models.Table, fk *models.Constraint)
 	relationship := models.InitRelationship(relationshipName, models.OneToMany)
 	relationship.FromTable = table.Name
 	relationship.FromSchema = table.Schema
+	relationship.FromColumns = append([]string(nil), fk.Columns...)
 	relationship.ToTable = fk.ReferencedTable
 	relationship.ToSchema = fk.ReferencedSchema
+	relationship.ToColumns = append([]string(nil), fk.ReferencedColumns...)
 	relationship.ForeignKey = fk.Name
 
 	// Store constraint actions in properties

pkg/readers/pgsql/reader_test.go

@@ -2,6 +2,7 @@ package pgsql
 
 import (
 	"os"
+	"reflect"
 	"testing"
 
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
@@ -359,6 +360,14 @@ func TestDeriveRelationship(t *testing.T) {
 		t.Errorf("Expected ToTable 'users', got '%s'", rel.ToTable)
 	}
 
+	if !reflect.DeepEqual(rel.FromColumns, []string{"user_id"}) {
+		t.Errorf("Expected FromColumns [user_id], got %v", rel.FromColumns)
+	}
+
+	if !reflect.DeepEqual(rel.ToColumns, []string{"id"}) {
+		t.Errorf("Expected ToColumns [id], got %v", rel.ToColumns)
+	}
+
 	if rel.ForeignKey != "fk_orders_user_id" {
 		t.Errorf("Expected ForeignKey 'fk_orders_user_id', got '%s'", rel.ForeignKey)
 	}

tests/postgres/issue21/schema.sql

@@ -0,0 +1,30 @@
+CREATE TABLE public.users (
+    id integer NOT NULL,
+    username varchar(255) NOT NULL,
+    email varchar(255) NOT NULL,
+    created_at timestamptz NOT NULL,
+    profile_id integer
+);
+
+CREATE TABLE public.profiles (
+    id integer NOT NULL,
+    bio text,
+    created_at timestamptz NOT NULL
+);
+
+CREATE TABLE public.posts (
+    id integer NOT NULL,
+    user_id integer NOT NULL,
+    title varchar(255) NOT NULL,
+    body text,
+    published_at timestamptz,
+    view_count integer DEFAULT 0
+);
+
+ALTER TABLE public.users ADD PRIMARY KEY (id);
+ALTER TABLE public.profiles ADD PRIMARY KEY (id);
+ALTER TABLE public.posts ADD PRIMARY KEY (id);
+
+CREATE UNIQUE INDEX posts_user_id_title_idx ON public.posts (user_id, title);
+
+ALTER TABLE public.users ADD CONSTRAINT users_profile_id_fkey FOREIGN KEY (profile_id) REFERENCES public.profiles (id);

tests/postgres/issue21/spec.dbml

@@ -0,0 +1,28 @@
+Table users {
+    id integer [pk, not null]
+    username varchar(255) [not null]
+    email varchar(255) [not null]
+    created_at timestamptz [not null]
+    profile_id integer
+}
+
+Table profiles {
+    id integer [pk, not null]
+    bio text
+    created_at timestamptz [not null]
+}
+
+Table posts {
+    id integer [pk, not null]
+    user_id integer [not null]
+    title varchar(255) [not null]
+    body text
+    published_at timestamptz
+    view_count integer default 0
+
+    Indexes {
+        (user_id, title) [unique]
+    }
+}
+
+Ref: users.profile_id > profiles.id