Fix few cases with postgres

migrator/migrator.go

@@ -74,7 +74,7 @@ func (m Migrator) FullDataTypeOf(field *schema.Field) (expr clause.Expr) {
 	}
 
 	if field.HasDefaultValue && field.DefaultValue != "" {
-		if field.DataType == schema.String {
+		if field.DataType == schema.String && field.DefaultValueInterface != nil {
 			defaultStmt := &gorm.Statement{Vars: []interface{}{field.DefaultValue}}
 			m.Dialector.BindVarTo(defaultStmt, defaultStmt, field.DefaultValue)
 			expr.SQL += " DEFAULT " + m.Dialector.Explain(defaultStmt.SQL.String(), field.DefaultValue)

schema/field.go

@@ -203,7 +203,10 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 		}
 	case reflect.String:
 		field.DataType = String
-		if field.HasDefaultValue {
+		isFunc := strings.Contains(field.DefaultValue, "(") &&
+			strings.Contains(field.DefaultValue, ")")
+
+		if field.HasDefaultValue && !isFunc {
 			field.DefaultValue = strings.Trim(field.DefaultValue, "'")
 			field.DefaultValue = strings.Trim(field.DefaultValue, "\"")
 			field.DefaultValueInterface = field.DefaultValue
@@ -253,6 +256,10 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 		}
 	}
 
+	if field.DataType == "" && field.DBDataType != "" {
+		field.DataType = String
+	}
+
 	// setup permission
 	if _, ok := field.TagSettings["-"]; ok {
 		field.Creatable = false

tests/go.mod

@@ -3,7 +3,9 @@ module gorm.io/gorm/tests
 go 1.14
 
 require (
+	github.com/google/uuid v1.1.1
 	github.com/jinzhu/now v1.1.1
+	github.com/lib/pq v1.6.0
 	gorm.io/driver/mysql v0.0.0-20200609004954-b8310c61c3f2
 	gorm.io/driver/postgres v0.0.0-20200602015520-15fcc29eb286
 	gorm.io/driver/sqlite v1.0.0

tests/postgres_test.go

@@ -0,0 +1,39 @@
+package tests_test
+
+import (
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/lib/pq"
+	"gorm.io/gorm"
+)
+
+func TestPostgres(t *testing.T) {
+	if DB.Dialector.Name() != "postgres" {
+		t.Skip()
+	}
+
+	type Harumph struct {
+		gorm.Model
+		Test   uuid.UUID      `gorm:"type:uuid;not null;default:gen_random_uuid()"`
+		Things pq.StringArray `gorm:"type:text[]"`
+	}
+
+	if err := DB.Exec("CREATE EXTENSION IF NOT EXISTS pgcrypto;").Error; err != nil {
+		t.Errorf("Failed to create extension pgcrypto, got error %v", err)
+	}
+
+	DB.Migrator().DropTable(&Harumph{})
+
+	if err := DB.AutoMigrate(&Harumph{}); err != nil {
+		t.Fatalf("Failed to migrate for uuid default value, got error: %v", err)
+	}
+
+	harumph := Harumph{}
+	DB.Create(&harumph)
+
+	var result Harumph
+	if err := DB.First(&result, "id = ?", harumph.ID).Error; err != nil {
+		t.Errorf("No error should happen, but got %v", err)
+	}
+}