From 2d0b215ef4dc42d4b3a0cb255fa3f69bcab3f984 Mon Sep 17 00:00:00 2001
From: Arseny Sazanov <arseny.sazanov@gmail.com>
Date: Fri, 29 Jan 2021 02:21:01 +0300
Subject: [PATCH] upgrade ORM alias support

---
 reflect/orm/orm.go      | 28 +++++++++++++++++++++------
 reflect/orm/orm_test.go | 42 ++++++++++++++++++++++++++++++++---------
 2 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/reflect/orm/orm.go b/reflect/orm/orm.go
index 8005c20..63365b5 100644
--- a/reflect/orm/orm.go
+++ b/reflect/orm/orm.go
@@ -34,6 +34,7 @@ type (
 		Aliases    []Alias
 		Join       Join
 		TableName  Table
+		TableAlias Alias
 		StructName Typ
 	}
 )
@@ -45,8 +46,10 @@ var (
 
 // custom tag for "sugar" columns values prepare for Update squirrel library staff
 const (
-	tagDB           = "db" // must be for all DTO structs fields, this tag also used by sqlx
-	tagOrmUseIN     = "orm_use_in"
+	tagDB       = "db" // must be for all DTO structs fields, this tag also used by sqlx
+	tagOrmUseIN = "orm_use_in"
+
+	underscored     = "_" // special name fo field contains tag orn_tab_name, orm_alias, orm_join
 	tagOrmAlias     = "orm_alias"
 	tagOrmJoin      = "orm_join"
 	tagOrmTableName = "orm_table_name"
@@ -108,17 +111,28 @@ func GetDataForUpdate(obj interface{}) map[Column]Argument {
 	return cv
 }
 
-func GetTableName(obj interface{}) string {
+func GetTableName(obj interface{}) Table {
 	meta := GetMetaDTO(obj)
 	return meta.TableName
 }
 
+func GetTableAlias(obj interface{}) Alias {
+	meta := GetMetaDTO(obj)
+	return meta.TableAlias
+}
+
+func GetTableNameWithAlias(obj interface{}) string {
+	meta := GetMetaDTO(obj)
+	if meta.TableName != "" && meta.TableAlias != "" {
+		return meta.TableName + " as " + meta.TableAlias
+	}
+	return ""
+}
+
 func getNoneCacheMetaDTO(obj interface{}) *MetaDTO {
 	meta := &MetaDTO{
 		ColsMap:    map[ormUseInTagValue][]Column{ormUseInSelect: {}, ormUseInCreate: {}, ormUseInUpdate: {}},
 		Aliases:    []Alias{},
-		Join:       "",
-		TableName:  "",
 		StructName: getObjTypeNameByReflect(obj),
 	}
 	if obj == nil {
@@ -129,6 +143,8 @@ func getNoneCacheMetaDTO(obj interface{}) *MetaDTO {
 
 	meta.TableName = getMetaInfoForOrmTagOnlyOne(tagOrmTableName, obj)
 
+	meta.TableAlias = getMetaInfoForOrmTagOnlyOne(tagOrmAlias, obj)
+
 	meta.Aliases = getMetaInfoForOrmAliasTag(obj)
 
 	for _, v := range []string{ormUseInSelect, ormUseInCreate, ormUseInUpdate} {
@@ -156,7 +172,7 @@ func getMetaInfoForOrmTagOnlyOne(value ormUseInTagValue, obj interface{}) string
 	for i := 0; i < t.NumField(); i++ {
 		field := t.Field(i)
 
-		if tagValue := field.Tag.Get(value); !isTagEmpty(tagValue) {
+		if tagValue := field.Tag.Get(value); !isTagEmpty(tagValue) && field.Name == underscored {
 			return tagValue // we search first usage of tag, for high root component only,
 		}
 	}
diff --git a/reflect/orm/orm_test.go b/reflect/orm/orm_test.go
index ef96b40..7dbe6f2 100644
--- a/reflect/orm/orm_test.go
+++ b/reflect/orm/orm_test.go
@@ -10,10 +10,10 @@ import (
 
 type (
 	BaseDTO struct {
-		ID        int64     `db:"id"          orm_use_in:"select"`
-		CreatedAt time.Time `db:"created_at"  orm_use_in:"select"`
-		UpdatedAt time.Time `db:"updated_at"  orm_use_in:"select,update"`
-		_         bool      `orm_use_in:"select,create,update"`
+		ID        int64       `db:"id"          orm_use_in:"select"`
+		CreatedAt time.Time   `db:"created_at"  orm_use_in:"select"`
+		UpdatedAt time.Time   `db:"updated_at"  orm_use_in:"select,update"`
+		_         interface{} `orm_use_in:"select,create,update"`
 	}
 
 	A struct {
@@ -23,14 +23,14 @@ type (
 		UpdateOnly   int    `db:"update_field"   orm_use_in:"update"`
 		NoDbTagField string `orm_use_for:"update"`
 		NoTagField   string
-		_            bool `orm_table_name:"A"`
+		_            interface{} `orm_table_name:"A" orm_alias:"a"`
 	}
 
 	B struct {
 		BaseDTO
-		CUS  float64 `db:"cus_field"   orm_use_in:"create,update,select"`
-		CUS2 int     `db:"cus2_field"  orm_use_in:"create,update,select"`
-		_    bool    `orm_table_name:"B"`
+		CUS  float64     `db:"cus_field"   orm_use_in:"create,update,select"`
+		CUS2 int         `db:"cus2_field"  orm_use_in:"create,update,select"`
+		_    interface{} `orm_table_name:"B" orm_alias:"b"`
 	}
 
 	C struct {
@@ -41,7 +41,8 @@ type (
 
 	BadStruct struct {
 		*A
-		_ struct{ a int }
+		_              struct{ a int }
+		bad_name_field interface{} `orm_table_name:"B" orm_alias:"b"`
 	}
 )
 
@@ -177,4 +178,27 @@ func (suite *OrmTestSuit) Test_GetTableName() {
 	assert.Equal(t, "B", GetTableName(&B{}))
 	assert.Equal(t, "", GetTableName(&C{}))
 	assert.Equal(t, "", GetTableName(nil))
+	assert.Equal(t, "", GetTableName(&BadStruct{}))
+}
+
+func (suite *OrmTestSuit) Test_GetTableAlias() {
+	t := suite.T()
+
+	assert.Equal(t, "a", GetTableAlias(&A{}))
+	assert.Equal(t, "b", GetTableAlias(&B{}))
+	assert.Equal(t, "", GetTableAlias(&C{}))
+	assert.Equal(t, "", GetTableAlias(nil))
+	assert.Equal(t, "", GetTableAlias(&BadStruct{}))
+}
+
+func (suite *OrmTestSuit) Test_GetTableNameWithAlias() {
+	t := suite.T()
+
+	_ = BadStruct{}.bad_name_field
+
+	assert.Equal(t, "A as a", GetTableNameWithAlias(&A{}))
+	assert.Equal(t, "B as b", GetTableNameWithAlias(&B{}))
+	assert.Equal(t, "", GetTableNameWithAlias(&C{}))
+	assert.Equal(t, "", GetTableNameWithAlias(nil))
+	assert.Equal(t, "", GetTableNameWithAlias(&BadStruct{}))
 }