fix(spec): unwrap SQL wrapper metadata types

pkg/resolvemcp/tools.go

@@ -85,13 +85,19 @@ func buildModelInfo(schema, entity string, model interface{}) modelInfo {
 
 		// Skip relation fields (slice or user-defined struct that isn't time.Time).
 		fieldType, found := modelType.FieldByName(d.Name)
+		var unwrappedType reflect.Type
+		isSQLType := false
 		if found {
 			ft := fieldType.Type
-			if ft.Kind() == reflect.Pointer {
+			if sqlType, ok := unwrapSQLType(ft); ok {
+				unwrappedType = sqlType
+				ft = sqlType
+				isSQLType = true
+			} else if ft.Kind() == reflect.Pointer {
 				ft = ft.Elem()
 			}
 			isUserStruct := ft.Kind() == reflect.Struct && ft.Name() != "Time" && ft.PkgPath() != ""
-			if ft.Kind() == reflect.Slice || isUserStruct {
+			if !isSQLType && (ft.Kind() == reflect.Slice || isUserStruct) {
 				info.relationNames = append(info.relationNames, jsonName)
 				continue
 			}
@@ -104,6 +110,9 @@ func buildModelInfo(schema, entity string, model interface{}) modelInfo {
 
 		// Derive Go type name, unwrapping pointer if needed.
 		goType := d.DataType
+		if isSQLType {
+			goType = unwrappedType.Name()
+		}
 		if goType == "" && found {
 			ft := fieldType.Type
 			for ft.Kind() == reflect.Pointer {
@@ -125,7 +134,7 @@ func buildModelInfo(schema, entity string, model interface{}) modelInfo {
 			isPrimary: isPrimary,
 			isUnique:  d.SQLKey == "unique" || d.SQLKey == "uniqueindex",
 			isFK:      d.SQLKey == "foreign_key",
-			nullable:  d.Nullable,
+			nullable:  isSQLType || d.Nullable,
 		}
 		info.columns = append(info.columns, ci)
 	}
@@ -134,6 +143,25 @@ func buildModelInfo(schema, entity string, model interface{}) modelInfo {
 	return info
 }
 
+// unwrapSQLType returns the value type wrapped by a spectypes SQL value. These
+// types are scalar columns even when their Go representation is a struct or a
+// slice (for example, SqlNull[string] and SqlJSONB).
+func unwrapSQLType(t reflect.Type) (reflect.Type, bool) {
+	for t.Kind() == reflect.Pointer {
+		t = t.Elem()
+	}
+
+	if t.PkgPath() != "github.com/bitechdev/ResolveSpec/pkg/spectypes" {
+		return nil, false
+	}
+	if t.Kind() == reflect.Struct {
+		if value, ok := t.FieldByName("Val"); ok {
+			return value.Type, true
+		}
+	}
+	return t, true
+}
+
 // fieldJSONName returns the JSON tag name for a struct field, falling back to the field name.
 func fieldJSONName(modelType reflect.Type, fieldName string) string {
 	field, ok := modelType.FieldByName(fieldName)

pkg/resolvemcp/tools_test.go

@@ -0,0 +1,34 @@
+package resolvemcp
+
+import (
+	"testing"
+
+	"github.com/bitechdev/ResolveSpec/pkg/spectypes"
+)
+
+func TestBuildModelInfo_UnwrapsSQLTypes(t *testing.T) {
+	type related struct {
+		ID int64 `json:"id"`
+	}
+	type model struct {
+		Name     spectypes.SqlString `gorm:"column:name" json:"name"`
+		Metadata spectypes.SqlJSONB  `gorm:"column:metadata;type:jsonb" json:"metadata"`
+		Related  related             `json:"related"`
+	}
+
+	info := buildModelInfo("public", "models", model{})
+	columns := make(map[string]columnInfo, len(info.columns))
+	for _, column := range info.columns {
+		columns[column.jsonName] = column
+	}
+
+	if column, ok := columns["name"]; !ok || column.goType != "string" || !column.nullable {
+		t.Errorf("expected name SQL wrapper column, got %+v", column)
+	}
+	if column, ok := columns["metadata"]; !ok || !column.nullable {
+		t.Errorf("expected metadata SQL wrapper column, got %+v", column)
+	}
+	if len(info.relationNames) != 1 || info.relationNames[0] != "related" {
+		t.Errorf("expected only related to be a relation, got %v", info.relationNames)
+	}
+}