export tag identifier (#1865)

#1864 Export tag identifier so we can change that form `xorm` to others

This will be useful when in some migration scenarios such as migrate `sqlx` to `xorm`, the former uses `db` as the identifier and has a very simple rule which can be covered by xorm parser rules

Co-authored-by: clannadxr <clannadxr@hotmail.com>
Reviewed-on: https://gitea.com/xorm/xorm/pulls/1865
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: clannadxr <clannadxr@noreply.gitea.io>
Co-committed-by: clannadxr <clannadxr@noreply.gitea.io>

engine.go

@@ -209,6 +209,11 @@ func (engine *Engine) SetColumnMapper(mapper names.Mapper) {
 	engine.tagParser.SetColumnMapper(mapper)
 }
 
+// SetTagIdentifier set the tag identifier
+func (engine *Engine) SetTagIdentifier(tagIdentifier string) {
+	engine.tagParser.SetIdentifier(tagIdentifier)
+}
+
 // Quote Use QuoteStr quote the string sql
 func (engine *Engine) Quote(value string) string {
 	value = strings.TrimSpace(value)

engine_group.go

@@ -167,6 +167,14 @@ func (eg *EngineGroup) SetMapper(mapper names.Mapper) {
 	}
 }
 
+// SetTagIdentifier set the tag identifier
+func (eg *EngineGroup) SetTagIdentifier(tagIdentifier string) {
+	eg.Engine.SetTagIdentifier(tagIdentifier)
+	for i := 0; i < len(eg.slaves); i++ {
+		eg.slaves[i].SetTagIdentifier(tagIdentifier)
+	}
+}
+
 // SetMaxIdleConns set the max idle connections on pool, default is 2
 func (eg *EngineGroup) SetMaxIdleConns(conns int) {
 	eg.Engine.DB().SetMaxIdleConns(conns)

interface.go

@@ -101,6 +101,7 @@ type EngineInterface interface {
 	SetCacher(string, caches.Cacher)
 	SetConnMaxLifetime(time.Duration)
 	SetColumnMapper(names.Mapper)
+	SetTagIdentifier(string)
 	SetDefaultCacher(caches.Cacher)
 	SetLogger(logger interface{})
 	SetLogLevel(log.LogLevel)

tags/parser.go

@@ -63,6 +63,11 @@ func (parser *Parser) SetColumnMapper(mapper names.Mapper) {
 	parser.columnMapper = mapper
 }
 
+func (parser *Parser) SetIdentifier(identifier string) {
+	parser.ClearCaches()
+	parser.identifier = identifier
+}
+
 func (parser *Parser) ParseWithCache(v reflect.Value) (*schemas.Table, error) {
 	t := v.Type()
 	tableI, ok := parser.tableCache.Load(t)

tags/parser_test.go

@@ -80,3 +80,26 @@ func TestUnexportField(t *testing.T) {
 		assert.NotEqual(t, "public", col.Name)
 	}
 }
+
+func TestParseWithOtherIdentifier(t *testing.T) {
+	parser := NewParser(
+		"xorm",
+		dialects.QueryDialect("mysql"),
+		names.GonicMapper{},
+		names.SnakeMapper{},
+		caches.NewManager(),
+	)
+
+	type StructWithDBTag struct {
+		FieldFoo string `db:"foo"`
+	}
+	parser.SetIdentifier("db")
+	table, err := parser.Parse(reflect.ValueOf(new(StructWithDBTag)))
+	assert.NoError(t, err)
+	assert.EqualValues(t, "struct_with_db_tag", table.Name)
+	assert.EqualValues(t, 1, len(table.Columns()))
+
+	for _, col := range table.Columns() {
+		assert.EqualValues(t, "foo", col.Name)
+	}
+}