From 79864af9ffee6e12051f6bbdfaab31df77f3bc61 Mon Sep 17 00:00:00 2001
From: Jinzhu <wosmvp@gmail.com>
Date: Wed, 30 Dec 2020 11:16:40 +0800
Subject: [PATCH] Allow customize auto increment increment

---
 callbacks/create.go |  4 +-
 schema/field.go     | 92 ++++++++++++++++++++++++---------------------
 2 files changed, 51 insertions(+), 45 deletions(-)

diff --git a/callbacks/create.go b/callbacks/create.go
index 052f3344..9166eb67 100644
--- a/callbacks/create.go
+++ b/callbacks/create.go
@@ -71,7 +71,7 @@ func Create(config *Config) func(db *gorm.DB) {
 												_, isZero := db.Statement.Schema.PrioritizedPrimaryField.ValueOf(rv)
 												if isZero {
 													db.Statement.Schema.PrioritizedPrimaryField.Set(rv, insertID)
-													insertID--
+													insertID -= db.Statement.Schema.PrioritizedPrimaryField.AutoIncrementIncrement
 												}
 											}
 										} else {
@@ -83,7 +83,7 @@ func Create(config *Config) func(db *gorm.DB) {
 
 												if _, isZero := db.Statement.Schema.PrioritizedPrimaryField.ValueOf(rv); isZero {
 													db.Statement.Schema.PrioritizedPrimaryField.Set(rv, insertID)
-													insertID++
+													insertID += db.Statement.Schema.PrioritizedPrimaryField.AutoIncrementIncrement
 												}
 											}
 										}
diff --git a/schema/field.go b/schema/field.go
index 86b4a061..17cc6c43 100644
--- a/schema/field.go
+++ b/schema/field.go
@@ -37,55 +37,57 @@ const (
 )
 
 type Field struct {
-	Name                  string
-	DBName                string
-	BindNames             []string
-	DataType              DataType
-	GORMDataType          DataType
-	PrimaryKey            bool
-	AutoIncrement         bool
-	Creatable             bool
-	Updatable             bool
-	Readable              bool
-	HasDefaultValue       bool
-	AutoCreateTime        TimeType
-	AutoUpdateTime        TimeType
-	DefaultValue          string
-	DefaultValueInterface interface{}
-	NotNull               bool
-	Unique                bool
-	Comment               string
-	Size                  int
-	Precision             int
-	Scale                 int
-	FieldType             reflect.Type
-	IndirectFieldType     reflect.Type
-	StructField           reflect.StructField
-	Tag                   reflect.StructTag
-	TagSettings           map[string]string
-	Schema                *Schema
-	EmbeddedSchema        *Schema
-	OwnerSchema           *Schema
-	ReflectValueOf        func(reflect.Value) reflect.Value
-	ValueOf               func(reflect.Value) (value interface{}, zero bool)
-	Set                   func(reflect.Value, interface{}) error
+	Name                   string
+	DBName                 string
+	BindNames              []string
+	DataType               DataType
+	GORMDataType           DataType
+	PrimaryKey             bool
+	AutoIncrement          bool
+	AutoIncrementIncrement int64
+	Creatable              bool
+	Updatable              bool
+	Readable               bool
+	HasDefaultValue        bool
+	AutoCreateTime         TimeType
+	AutoUpdateTime         TimeType
+	DefaultValue           string
+	DefaultValueInterface  interface{}
+	NotNull                bool
+	Unique                 bool
+	Comment                string
+	Size                   int
+	Precision              int
+	Scale                  int
+	FieldType              reflect.Type
+	IndirectFieldType      reflect.Type
+	StructField            reflect.StructField
+	Tag                    reflect.StructTag
+	TagSettings            map[string]string
+	Schema                 *Schema
+	EmbeddedSchema         *Schema
+	OwnerSchema            *Schema
+	ReflectValueOf         func(reflect.Value) reflect.Value
+	ValueOf                func(reflect.Value) (value interface{}, zero bool)
+	Set                    func(reflect.Value, interface{}) error
 }
 
 func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 	var err error
 
 	field := &Field{
-		Name:              fieldStruct.Name,
-		BindNames:         []string{fieldStruct.Name},
-		FieldType:         fieldStruct.Type,
-		IndirectFieldType: fieldStruct.Type,
-		StructField:       fieldStruct,
-		Creatable:         true,
-		Updatable:         true,
-		Readable:          true,
-		Tag:               fieldStruct.Tag,
-		TagSettings:       ParseTagSetting(fieldStruct.Tag.Get("gorm"), ";"),
-		Schema:            schema,
+		Name:                   fieldStruct.Name,
+		BindNames:              []string{fieldStruct.Name},
+		FieldType:              fieldStruct.Type,
+		IndirectFieldType:      fieldStruct.Type,
+		StructField:            fieldStruct,
+		Creatable:              true,
+		Updatable:              true,
+		Readable:               true,
+		Tag:                    fieldStruct.Tag,
+		TagSettings:            ParseTagSetting(fieldStruct.Tag.Get("gorm"), ";"),
+		Schema:                 schema,
+		AutoIncrementIncrement: 1,
 	}
 
 	for field.IndirectFieldType.Kind() == reflect.Ptr {
@@ -149,6 +151,10 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 		field.HasDefaultValue = true
 	}
 
+	if num, ok := field.TagSettings["AUTOINCREMENTINCREMENT"]; ok {
+		field.AutoIncrementIncrement, _ = strconv.ParseInt(num, 10, 64)
+	}
+
 	if v, ok := field.TagSettings["DEFAULT"]; ok {
 		field.HasDefaultValue = true
 		field.DefaultValue = v