From 29ac1920900ed00e18f838cba30d717b3dd8bc85 Mon Sep 17 00:00:00 2001
From: Jinzhu <wosmvp@gmail.com>
Date: Wed, 2 Jul 2014 17:47:30 +0800
Subject: [PATCH] Add Compatibility Mode

---
 common_dialect.go | 100 ++++++++++++++++++++++++++++++++++++++++++++++
 dialect.go        |   4 ++
 main_test.go      |  20 ++++++++++
 3 files changed, 124 insertions(+)
 create mode 100644 common_dialect.go

diff --git a/common_dialect.go b/common_dialect.go
new file mode 100644
index 00000000..7d5d76fa
--- /dev/null
+++ b/common_dialect.go
@@ -0,0 +1,100 @@
+package gorm
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+type commonDialect struct{}
+
+func (s *commonDialect) BinVar(i int) string {
+	return "?"
+}
+
+func (s *commonDialect) SupportLastInsertId() bool {
+	return true
+}
+
+func (d *commonDialect) SqlTag(value reflect.Value, size int) string {
+	switch value.Kind() {
+	case reflect.Bool:
+		return "BOOLEAN"
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uintptr:
+		return "INTEGER"
+	case reflect.Int64, reflect.Uint64:
+		return "BIGINT"
+	case reflect.Float32, reflect.Float64:
+		return "FLOAT"
+	case reflect.String:
+		if size > 0 && size < 65532 {
+			return fmt.Sprintf("VARCHAR(%d)", size)
+		} else {
+			return "VARCHAR(65532)"
+		}
+	case reflect.Struct:
+		if value.Type() == timeType {
+			return "TIMESTAMP"
+		}
+	default:
+		if _, ok := value.Interface().([]byte); ok {
+			if size > 0 && size < 65532 {
+				return fmt.Sprintf("BINARY(%d)", size)
+			} else {
+				return "BINARY(65532)"
+			}
+		}
+	}
+	panic(fmt.Sprintf("invalid sql type %s (%s) for commonDialect", value.Type().Name(), value.Kind().String()))
+}
+
+func (s *commonDialect) PrimaryKeyTag(value reflect.Value, size int) string {
+	suffix_str := " NOT NULL PRIMARY KEY"
+	switch value.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uintptr:
+		return "INTEGER" + suffix_str
+	case reflect.Int64, reflect.Uint64:
+		return "BIGINT" + suffix_str
+	default:
+		panic("Invalid primary key type")
+	}
+}
+
+func (s *commonDialect) ReturningStr(key string) string {
+	return ""
+}
+
+func (s *commonDialect) Quote(key string) string {
+	return fmt.Sprintf("`%s`", key)
+}
+
+func (s *commonDialect) databaseName(scope *Scope) string {
+	from := strings.Index(scope.db.parent.source, "/") + 1
+	to := strings.Index(scope.db.parent.source, "?")
+	if to == -1 {
+		to = len(scope.db.parent.source)
+	}
+	return scope.db.parent.source[from:to]
+}
+
+func (s *commonDialect) HasTable(scope *Scope, tableName string) bool {
+	var count int
+	newScope := scope.New(nil)
+	newScope.Raw(fmt.Sprintf("SELECT count(*) FROM INFORMATION_SCHEMA.tables where table_name = %v AND table_schema = %v",
+		newScope.AddToVars(tableName),
+		newScope.AddToVars(s.databaseName(scope))))
+	newScope.DB().QueryRow(newScope.Sql, newScope.SqlVars...).Scan(&count)
+	return count > 0
+}
+
+func (s *commonDialect) HasColumn(scope *Scope, tableName string, columnName string) bool {
+	var count int
+	newScope := scope.New(nil)
+	newScope.Raw(fmt.Sprintf("SELECT count(*) FROM information_schema.columns WHERE table_schema = %v AND table_name = %v AND column_name = %v",
+		newScope.AddToVars(s.databaseName(scope)),
+		newScope.AddToVars(tableName),
+		newScope.AddToVars(columnName),
+	))
+	newScope.DB().QueryRow(newScope.Sql, newScope.SqlVars...).Scan(&count)
+	return count > 0
+}
diff --git a/dialect.go b/dialect.go
index d1176039..20ba32d4 100644
--- a/dialect.go
+++ b/dialect.go
@@ -1,6 +1,7 @@
 package gorm
 
 import (
+	"fmt"
 	"reflect"
 	"time"
 )
@@ -27,6 +28,9 @@ func NewDialect(driver string) Dialect {
 		d = &mysql{}
 	case "sqlite3":
 		d = &sqlite3{}
+	default:
+		fmt.Printf("`%v` is not officially supported, running under compatibility mode.\n", driver)
+		d = &commonDialect{}
 	}
 	return d
 }
diff --git a/main_test.go b/main_test.go
index 39aac884..6616b992 100644
--- a/main_test.go
+++ b/main_test.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 
+	testdb "github.com/erikstmartin/go-testdb"
 	_ "github.com/go-sql-driver/mysql"
 	"github.com/jinzhu/gorm"
 	_ "github.com/lib/pq"
@@ -2098,3 +2099,22 @@ func TestCreate(t *testing.T) {
 		t.Error("Should not be able to create record with predefined duplicate Id")
 	}
 }
+
+func TestCompatibilityMode(t *testing.T) {
+	db, _ := gorm.Open("testdb", "")
+	testdb.SetQueryFunc(func(query string) (driver.Rows, error) {
+		columns := []string{"id", "name", "age"}
+		result := `
+		1,Tim,20
+		2,Joe,25
+		3,Bob,30
+		`
+		return testdb.RowsFromCSVString(columns, result), nil
+	})
+
+	var users []User
+	db.Find(&users)
+	if (users[0].Name != "Tim") || len(users) != 3 {
+		t.Errorf("Unexcepted result returned")
+	}
+}