From 3a97639880a6a965c5e8209e2ff5557008e8b191 Mon Sep 17 00:00:00 2001
From: Jinzhu <wosmvp@gmail.com>
Date: Sun, 23 Aug 2020 10:40:37 +0800
Subject: [PATCH] Fix unordered joins, close #3267

---
 callbacks/query.go  |  8 ++++----
 chainable_api.go    |  5 +----
 statement.go        | 13 +++++++++----
 tests/joins_test.go |  8 ++++++++
 4 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/callbacks/query.go b/callbacks/query.go
index 5ae1e904..f6cb32d5 100644
--- a/callbacks/query.go
+++ b/callbacks/query.go
@@ -104,12 +104,12 @@ func BuildQuerySQL(db *gorm.DB) {
 		}
 
 		joins := []clause.Join{}
-		for name, conds := range db.Statement.Joins {
+		for _, join := range db.Statement.Joins {
 			if db.Statement.Schema == nil {
 				joins = append(joins, clause.Join{
-					Expression: clause.Expr{SQL: name, Vars: conds},
+					Expression: clause.Expr{SQL: join.Name, Vars: join.Conds},
 				})
-			} else if relation, ok := db.Statement.Schema.Relationships.Relations[name]; ok {
+			} else if relation, ok := db.Statement.Schema.Relationships.Relations[join.Name]; ok {
 				tableAliasName := relation.Name
 
 				for _, s := range relation.FieldSchema.DBNames {
@@ -149,7 +149,7 @@ func BuildQuerySQL(db *gorm.DB) {
 				})
 			} else {
 				joins = append(joins, clause.Join{
-					Expression: clause.Expr{SQL: name, Vars: conds},
+					Expression: clause.Expr{SQL: join.Name, Vars: join.Conds},
 				})
 			}
 		}
diff --git a/chainable_api.go b/chainable_api.go
index 9b46a95b..e1b73457 100644
--- a/chainable_api.go
+++ b/chainable_api.go
@@ -172,10 +172,7 @@ func (db *DB) Or(query interface{}, args ...interface{}) (tx *DB) {
 //     db.Joins("JOIN emails ON emails.user_id = users.id AND emails.email = ?", "jinzhu@example.org").Find(&user)
 func (db *DB) Joins(query string, args ...interface{}) (tx *DB) {
 	tx = db.getInstance()
-	if tx.Statement.Joins == nil {
-		tx.Statement.Joins = map[string][]interface{}{}
-	}
-	tx.Statement.Joins[query] = args
+	tx.Statement.Joins = append(tx.Statement.Joins, join{Name: query, Conds: args})
 	return
 }
 
diff --git a/statement.go b/statement.go
index 6114f468..214a15bb 100644
--- a/statement.go
+++ b/statement.go
@@ -29,7 +29,7 @@ type Statement struct {
 	Distinct             bool
 	Selects              []string // selected columns
 	Omits                []string // omit columns
-	Joins                map[string][]interface{}
+	Joins                []join
 	Preloads             map[string][]interface{}
 	Settings             sync.Map
 	ConnPool             ConnPool
@@ -44,6 +44,11 @@ type Statement struct {
 	assigns              []interface{}
 }
 
+type join struct {
+	Name  string
+	Conds []interface{}
+}
+
 // StatementModifier statement modifier interface
 type StatementModifier interface {
 	ModifyStatement(*Statement)
@@ -401,7 +406,6 @@ func (stmt *Statement) clone() *Statement {
 		Distinct:             stmt.Distinct,
 		Selects:              stmt.Selects,
 		Omits:                stmt.Omits,
-		Joins:                map[string][]interface{}{},
 		Preloads:             map[string][]interface{}{},
 		ConnPool:             stmt.ConnPool,
 		Schema:               stmt.Schema,
@@ -417,8 +421,9 @@ func (stmt *Statement) clone() *Statement {
 		newStmt.Preloads[k] = p
 	}
 
-	for k, j := range stmt.Joins {
-		newStmt.Joins[k] = j
+	if len(stmt.Joins) > 0 {
+		newStmt.Joins = make([]join, len(stmt.Joins))
+		copy(newStmt.Joins, stmt.Joins)
 	}
 
 	stmt.Settings.Range(func(k, v interface{}) bool {
diff --git a/tests/joins_test.go b/tests/joins_test.go
index e54d3784..f78ddf67 100644
--- a/tests/joins_test.go
+++ b/tests/joins_test.go
@@ -1,6 +1,7 @@
 package tests_test
 
 import (
+	"regexp"
 	"sort"
 	"testing"
 
@@ -88,6 +89,13 @@ func TestJoinConds(t *testing.T) {
 	if db5.Error != nil {
 		t.Errorf("Should not raise error for join where identical fields in different tables. Error: %s", db5.Error.Error())
 	}
+
+	dryDB := DB.Session(&gorm.Session{DryRun: true})
+	stmt := dryDB.Joins("left join pets on pets.user_id = users.id AND pets.name = ?", user.Pets[0].Name).Joins("join accounts on accounts.user_id = users.id AND accounts.number = ?", user.Account.Number).Where(User{Model: gorm.Model{ID: 1}}).Where(Account{Model: gorm.Model{ID: 1}}).Not(Pet{Model: gorm.Model{ID: 1}}).Find(&users5).Statement
+
+	if !regexp.MustCompile("SELECT .* FROM .users. left join pets.*join accounts.*").MatchString(stmt.SQL.String()) {
+		t.Errorf("joins should be ordered, but got %v", stmt.SQL.String())
+	}
 }
 
 func TestJoinsWithSelect(t *testing.T) {