Batch insert through a new callback

callback.go

@@ -16,6 +16,7 @@ var DefaultCallback = &Callback{}
 //   Field `processors` contains all callback processors, will be used to generate above callbacks in order
 type Callback struct {
 	creates      []*func(scope *Scope)
+	createsBatch []*func(scope *Scope)
 	updates      []*func(scope *Scope)
 	deletes      []*func(scope *Scope)
 	queries      []*func(scope *Scope)
@@ -38,6 +39,7 @@ type CallbackProcessor struct {
 func (c *Callback) clone() *Callback {
 	return &Callback{
 		creates:      c.creates,
+		createsBatch: c.createsBatch,
 		updates:      c.updates,
 		deletes:      c.deletes,
 		queries:      c.queries,
@@ -58,6 +60,11 @@ func (c *Callback) Create() *CallbackProcessor {
 	return &CallbackProcessor{kind: "create", parent: c}
 }
 
+// CreateBatch could be used to register callbacks for creating objects in bulk operations
+func (c *Callback) CreateBatch() *CallbackProcessor {
+	return &CallbackProcessor{kind: "creates_batch", parent: c}
+}
+
 // Update could be used to register callbacks for updating object, refer `Create` for usage
 func (c *Callback) Update() *CallbackProcessor {
 	return &CallbackProcessor{kind: "update", parent: c}
@@ -217,13 +224,15 @@ func sortProcessors(cps []*CallbackProcessor) []*func(scope *Scope) {
 
 // reorder all registered processors, and reset CRUD callbacks
 func (c *Callback) reorder() {
-	var creates, updates, deletes, queries, rowQueries []*CallbackProcessor
+	var creates, createsBatch, updates, deletes, queries, rowQueries []*CallbackProcessor
 
 	for _, processor := range c.processors {
 		if processor.name != "" {
 			switch processor.kind {
 			case "create":
 				creates = append(creates, processor)
+			case "creates_batch":
+				createsBatch = append(createsBatch, processor)
 			case "update":
 				updates = append(updates, processor)
 			case "delete":
@@ -237,6 +246,7 @@ func (c *Callback) reorder() {
 	}
 
 	c.creates = sortProcessors(creates)
+	c.createsBatch = sortProcessors(createsBatch)
 	c.updates = sortProcessors(updates)
 	c.deletes = sortProcessors(deletes)
 	c.queries = sortProcessors(queries)

callback_create_batch.go

@@ -0,0 +1,144 @@
+package gorm
+
+import (
+	"fmt"
+	"reflect"
+
+	"strings"
+)
+
+// Define callbacks for batch creating
+func init() {
+	DefaultCallback.CreateBatch().Register("gorm:begin_transaction", beginTransactionCallback)
+	DefaultCallback.CreateBatch().Register("gorm:create_batch", createBatchCallback)
+	DefaultCallback.CreateBatch().Register("gorm:commit_or_rollback_transaction", commitOrRollbackTransactionCallback)
+}
+
+// createCallback the callback used to insert data into database
+func createBatchCallback(scope *Scope) {
+	value := scope.IndirectValue()
+
+	if value.Kind() != reflect.Slice {
+		scope.Err(fmt.Errorf("createBatchCallback cannot be called for non-slice value, %+v given", value.Interface()))
+		return
+	}
+
+	var (
+		columns                      []string                        // one-dimensional array of strings containing columns
+		blankColumnsWithDefaultValue []string                        // one-dimensional array of strings containing columns
+		placeholders                 = make([][]string, value.Len()) // two-dimensional array of strings containing value placeholders
+		structFields                 = scope.GetModelStruct().StructFields
+	)
+
+	// Filling up the columns
+	for _, field := range fields(scope) {
+		// We don't treat non-normal fields on batch operations (relationships, etc)
+		if !field.IsNormal {
+			continue
+		}
+
+		if field.IsBlank && field.HasDefaultValue {
+			blankColumnsWithDefaultValue = append(blankColumnsWithDefaultValue, scope.Quote(field.DBName))
+			scope.InstanceSet("gorm:blank_columns_with_default_value", blankColumnsWithDefaultValue)
+		} else if !field.IsPrimaryKey || !field.IsBlank {
+			columns = append(columns, scope.Quote(field.DBName))
+		}
+	}
+
+	// Filling up the placeholders
+	for elementIndex := 0; elementIndex < value.Len(); elementIndex++ {
+		valuePlaceholders := []string{}
+
+		for _, structField := range structFields {
+			// When inserting, the primary key is usually auto-increment
+			if !structField.IsPrimaryKey {
+				fieldValue := reflect.Indirect(value.Index(elementIndex)).FieldByName(structField.Names[0]).Interface()
+				valuePlaceholders = append(valuePlaceholders, scope.AddToVars(fieldValue))
+			}
+		}
+
+		placeholders[elementIndex] = valuePlaceholders
+	}
+
+	var (
+		returningColumn = "*"
+		quotedTableName = scope.QuotedTableName()
+		primaryField    = scope.PrimaryField()
+		extraOption     string
+	)
+
+	if str, ok := scope.Get("gorm:insert_option"); ok {
+		extraOption = fmt.Sprint(str)
+	}
+
+	if primaryField != nil {
+		returningColumn = scope.Quote(primaryField.DBName)
+	}
+
+	lastInsertIDReturningSuffix := scope.Dialect().LastInsertIDReturningSuffix(quotedTableName, returningColumn)
+
+	scope.Raw(fmt.Sprintf(
+		"INSERT INTO %v (%v) VALUES %v%v%v",
+		scope.QuotedTableName(),
+		strings.Join(columns, ","),
+		strings.Join(joinValuePlaceholders(placeholders), ","),
+		addExtraSpaceIfExist(extraOption),
+		addExtraSpaceIfExist(lastInsertIDReturningSuffix),
+	))
+
+	// Executing the query
+	// TODO(drgomesp): Do we really need this check?
+	if lastInsertIDReturningSuffix == "" || primaryField == nil {
+		if result, err := scope.SQLDB().Exec(scope.SQL, scope.SQLVars...); scope.Err(err) == nil {
+			// set rows affected count
+			scope.db.RowsAffected, _ = result.RowsAffected()
+
+			if firstInsertedID, err := result.LastInsertId(); scope.Err(err) == nil {
+				fillPrimaryKeys(structFields, firstInsertedID, &value)
+			}
+		}
+	}
+}
+
+func fillPrimaryKeys(structFields []*StructField, firstInsertedID int64, values *reflect.Value) {
+	for _, structField := range structFields {
+		for i := 0; i < values.Len(); i++ {
+			field := reflect.Indirect(values.Index(i)).FieldByName(structField.Names[0])
+
+			if field.IsValid() && field.CanSet() {
+				if field.Kind() == reflect.Int64 || field.Kind() == reflect.Int32 || field.Kind() == reflect.Int8 || field.Kind() == reflect.Int {
+					id := firstInsertedID + int64(i)
+
+					if !field.OverflowInt(id) {
+						field.SetInt(id)
+					}
+				}
+			}
+		}
+	}
+}
+
+func joinValuePlaceholders(placeholders [][]string) []string {
+	var valuePlaceholders []string
+
+	for _, placeholder := range placeholders {
+		valuePlaceholders = append(valuePlaceholders, fmt.Sprintf("(%s)", strings.Join(placeholder, ",")))
+	}
+
+	return valuePlaceholders
+}
+
+func fields(scope *Scope) []*Field {
+	var (
+		indirectScopeValue = scope.IndirectValue()
+		structFields       = scope.GetModelStruct().StructFields
+		fields             = make([]*Field, len(structFields))
+	)
+
+	for i, structField := range structFields {
+		fieldValue := reflect.Indirect(indirectScopeValue.Index(0)).FieldByName(structField.Names[0])
+		fields[i] = &Field{StructField: structField, Field: fieldValue, IsBlank: isBlank(fieldValue)}
+	}
+
+	return fields
+}

main.go

@@ -407,6 +407,12 @@ func (s *DB) Create(value interface{}) *DB {
 	return scope.callCallbacks(s.parent.callbacks.creates).db
 }
 
+// CreateBatch inserts multiple values into the database via a bulk operation
+func (s *DB) CreateBatch(value interface{}) *DB {
+	scope := s.clone().NewScope(value)
+	return scope.callCallbacks(s.parent.callbacks.createsBatch).db
+}
+
 // Delete delete value match given conditions, if the value has primary key, then will including the primary key as condition
 func (s *DB) Delete(value interface{}, where ...interface{}) *DB {
 	return s.clone().NewScope(value).inlineCondition(where...).callCallbacks(s.parent.callbacks.deletes).db