Add ability to set custom column types in the gorm tag, so things suc…

…h as lengths can be added.

This allows customisation in the same was as already implemented for data types using WithDataTypeMap.

config.go

@@ -55,6 +55,7 @@ type Config struct {
 	fileNameNS  func(tableName string) (fileName string)
 
 	dataTypeMap    map[string]func(columnType gorm.ColumnType) (dataType string)
+	columnTypeMap  map[string]func(columnType gorm.ColumnType) (colType string)
 	fieldJSONTagNS func(columnName string) (tagContent string)
 
 	modelOpts []ModelOpt
@@ -98,6 +99,11 @@ func (cfg *Config) WithDataTypeMap(newMap map[string]func(columnType gorm.Column
 	cfg.dataTypeMap = newMap
 }
 
+// WithColumnTypeMap specify column type mapping relationship, only work when syncing table from db
+func (cfg *Config) WithColumnTypeMap(newMap map[string]func(columnType gorm.ColumnType) (colType string)) {
+	cfg.columnTypeMap = newMap
+}
+
 // WithJSONTagNameStrategy specify json tag naming strategy
 func (cfg *Config) WithJSONTagNameStrategy(ns func(columnName string) (tagContent string)) {
 	cfg.fieldJSONTagNS = ns

generator.go

@@ -174,7 +174,8 @@ func (g *Generator) genModelConfig(tableName string, modelName string, modelOpts
 			FileNameNS:     g.fileNameNS,
 		},
 		FieldConfig: model.FieldConfig{
-			DataTypeMap: g.dataTypeMap,
+			DataTypeMap:   g.dataTypeMap,
+			ColumnTypeMap: g.columnTypeMap,
 
 			FieldSignable:     g.FieldSignable,
 			FieldNullable:     g.FieldNullable,

internal/generate/generate.go

@@ -19,6 +19,7 @@ import (
 func getFields(db *gorm.DB, conf *model.Config, columns []*model.Column) (fields []*model.Field) {
 	for _, col := range columns {
 		col.SetDataTypeMap(conf.DataTypeMap)
+		col.SetColumnTypeMap(conf.ColumnTypeMap)
 		col.WithNS(conf.FieldJSONTagNS)
 
 		m := col.ToField(conf.FieldNullable, conf.FieldCoverable, conf.FieldSignable)

internal/model/config.go

@@ -33,7 +33,8 @@ type NameStrategy struct {
 
 // FieldConfig field configuration
 type FieldConfig struct {
-	DataTypeMap map[string]func(columnType gorm.ColumnType) (dataType string)
+	DataTypeMap   map[string]func(columnType gorm.ColumnType) (dataType string)
+	ColumnTypeMap map[string]func(columnType gorm.ColumnType) (colType string)
 
 	FieldNullable     bool // generate pointer when field is nullable
 	FieldCoverable    bool // generate pointer when field has default value

internal/model/tbl_column.go

@@ -12,18 +12,24 @@ import (
 // Column table column's info
 type Column struct {
 	gorm.ColumnType
-	TableName   string                                                        `gorm:"column:TABLE_NAME"`
-	Indexes     []*Index                                                      `gorm:"-"`
-	UseScanType bool                                                          `gorm:"-"`
-	dataTypeMap map[string]func(columnType gorm.ColumnType) (dataType string) `gorm:"-"`
-	jsonTagNS   func(columnName string) string                                `gorm:"-"`
+	TableName     string                                                        `gorm:"column:TABLE_NAME"`
+	Indexes       []*Index                                                      `gorm:"-"`
+	UseScanType   bool                                                          `gorm:"-"`
+	dataTypeMap   map[string]func(columnType gorm.ColumnType) (dataType string) `gorm:"-"`
+	columnTypeMap map[string]func(columnType gorm.ColumnType) (colType string)  `gorm:"-"`
+	jsonTagNS     func(columnName string) string                                `gorm:"-"`
 }
 
 // SetDataTypeMap set data type map
 func (c *Column) SetDataTypeMap(m map[string]func(columnType gorm.ColumnType) (dataType string)) {
 	c.dataTypeMap = m
 }
 
+// SetColumnTypeMap set column type map
+func (c *Column) SetColumnTypeMap(m map[string]func(columnType gorm.ColumnType) (colType string)) {
+	c.columnTypeMap = m
+}
+
 // GetDataType get data type
 func (c *Column) GetDataType() (fieldtype string) {
 	if mapping, ok := c.dataTypeMap[c.DatabaseTypeName()]; ok {
@@ -155,6 +161,9 @@ func (c *Column) defaultTagValue() string {
 
 func (c *Column) columnType() (v string) {
 	if cl, ok := c.ColumnType.ColumnType(); ok {
+		if mapping, ok := c.columnTypeMap[cl]; ok {
+			return mapping(c.ColumnType)
+		}
 		return cl
 	}
 	return c.DatabaseTypeName()