Build relationships if fields are not ignored, fix #3181

schema/relationship.go

@@ -300,7 +300,7 @@ func (schema *Schema) buildMany2ManyRelation(relation *Relationship, field *Fiel
 
 	// build references
 	for _, f := range relation.JoinTable.Fields {
-		if f.Creatable {
+		if f.Creatable || f.Readable || f.Updatable {
 			// use same data type for foreign keys
 			f.DataType = fieldsMap[f.Name].DataType
 			f.GORMDataType = fieldsMap[f.Name].GORMDataType

schema/relationship_test.go

@@ -220,6 +220,29 @@ func TestMany2ManyOverrideJoinForeignKey(t *testing.T) {
 	})
 }
 
+func TestBuildReadonlyMany2ManyRelation(t *testing.T) {
+	type Profile struct {
+		gorm.Model
+		Name      string
+		UserRefer uint
+	}
+
+	type User struct {
+		gorm.Model
+		Profiles []Profile `gorm:"->;many2many:user_profile;JoinForeignKey:UserReferID;JoinReferences:ProfileRefer"`
+		Refer    uint
+	}
+
+	checkStructRelation(t, &User{}, Relation{
+		Name: "Profiles", Type: schema.Many2Many, Schema: "User", FieldSchema: "Profile",
+		JoinTable: JoinTable{Name: "user_profile", Table: "user_profile"},
+		References: []Reference{
+			{"ID", "User", "UserReferID", "user_profile", "", true},
+			{"ID", "Profile", "ProfileRefer", "user_profile", "", false},
+		},
+	})
+}
+
 func TestMany2ManyWithMultiPrimaryKeys(t *testing.T) {
 	type Tag struct {
 		ID     uint   `gorm:"primary_key"`

schema/schema.go

@@ -133,7 +133,7 @@ func Parse(dest interface{}, cacheStore *sync.Map, namer Namer) (*Schema, error)
 
 		if field.DBName != "" {
 			// nonexistence or shortest path or first appear prioritized if has permission
-			if v, ok := schema.FieldsByDBName[field.DBName]; !ok || (field.Creatable && len(field.BindNames) < len(v.BindNames)) {
+			if v, ok := schema.FieldsByDBName[field.DBName]; !ok || ((field.Creatable || field.Updatable || field.Readable) && len(field.BindNames) < len(v.BindNames)) {
 				if _, ok := schema.FieldsByDBName[field.DBName]; !ok {
 					schema.DBNames = append(schema.DBNames, field.DBName)
 				}
@@ -219,7 +219,7 @@ func Parse(dest interface{}, cacheStore *sync.Map, namer Namer) (*Schema, error)
 	if _, loaded := cacheStore.LoadOrStore(modelType, schema); !loaded {
 		if _, embedded := schema.cacheStore.Load(embeddedCacheKey); !embedded {
 			for _, field := range schema.Fields {
-				if field.DataType == "" && field.Creatable {
+				if field.DataType == "" && (field.Creatable || field.Updatable || field.Readable) {
 					if schema.parseRelation(field); schema.err != nil {
 						return schema, schema.err
 					}