add comment support on create table

.sql

@@ -0,0 +1,2 @@
+/*Generated by xorm v0.6.2.0605 2017-06-14 14:05:59, from sqlite3 to SQLITE3*/
+

tag.go

@@ -54,6 +54,7 @@ var (
 		"UNIQUE":   UniqueTagHandler,
 		"CACHE":    CacheTagHandler,
 		"NOCACHE":  NoCacheTagHandler,
+		"COMMENT":  CommentTagHandler,
 	}
 )
 
@@ -192,6 +193,14 @@ func UniqueTagHandler(ctx *tagContext) error {
 	return nil
 }
 
+// CommentTagHandler add comment to column
+func CommentTagHandler(ctx *tagContext) error {
+	if len(ctx.params) > 0 {
+		ctx.col.Comment = strings.Trim(ctx.params[0], "' ")
+	}
+	return nil
+}
+
 // SQLTypeTagHandler describes SQL Type tag handler
 func SQLTypeTagHandler(ctx *tagContext) error {
 	ctx.col.SQLType = core.SQLType{Name: ctx.tagName}

tag_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/go-xorm/core"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -235,3 +236,37 @@ func TestAutoIncrTag(t *testing.T) {
 	assert.True(t, cols[0].IsPrimaryKey)
 	assert.Equal(t, "id", cols[0].Name)
 }
+
+func TestTagComment(t *testing.T) {
+	assert.NoError(t, prepareEngine())
+	// FIXME: only support mysql
+	if testEngine.dialect.DriverName() != core.MYSQL {
+		return
+	}
+
+	type TestComment1 struct {
+		Id int64 `xorm:"comment(主键)"`
+	}
+
+	assert.NoError(t, testEngine.Sync2(new(TestComment1)))
+
+	tables, err := testEngine.DBMetas()
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, len(tables))
+	assert.EqualValues(t, 1, len(tables[0].Columns()))
+	assert.EqualValues(t, "主键", tables[0].Columns()[0].Comment)
+
+	assert.NoError(t, testEngine.DropTables(new(TestComment1)))
+
+	type TestComment2 struct {
+		Id int64 `xorm:"comment('主键')"`
+	}
+
+	assert.NoError(t, testEngine.Sync2(new(TestComment2)))
+
+	tables, err = testEngine.DBMetas()
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, len(tables))
+	assert.EqualValues(t, 1, len(tables[0].Columns()))
+	assert.EqualValues(t, "主键", tables[0].Columns()[0].Comment)
+}