improve count usage (#654)

session_stats.go

@@ -18,10 +18,7 @@ func (session *Session) Count(bean ...interface{}) (int64, error) {
 	var args []interface{}
 	var err error
 	if session.Statement.RawSQL == "" {
-		if len(bean) == 0 {
-			return 0, ErrTableNotFound
-		}
-		sqlStr, args, err = session.Statement.genCountSQL(bean[0])
+		sqlStr, args, err = session.Statement.genCountSQL(bean...)
 		if err != nil {
 			return 0, err
 		}

session_stats_test.go

@@ -127,6 +127,14 @@ func TestCount(t *testing.T) {
 	total, err = testEngine.Where(cond).Count(new(UserinfoCount))
 	assert.NoError(t, err)
 	assert.EqualValues(t, 1, total)
+
+	total, err = testEngine.Where(cond).Table("userinfo_count").Count()
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, total)
+
+	total, err = testEngine.Table("userinfo_count").Count()
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, total)
 }
 
 func TestSQLCount(t *testing.T) {

statement.go

@@ -981,10 +981,16 @@ func (statement *Statement) genGetSQL(bean interface{}) (string, []interface{},
 	return sqlStr, append(statement.joinArgs, condArgs...), nil
 }
 
-func (statement *Statement) genCountSQL(bean interface{}) (string, []interface{}, error) {
-	statement.setRefValue(rValue(bean))
-
-	condSQL, condArgs, err := statement.genConds(bean)
+func (statement *Statement) genCountSQL(beans ...interface{}) (string, []interface{}, error) {
+	var condSQL string
+	var condArgs []interface{}
+	var err error
+	if len(beans) > 0 {
+		statement.setRefValue(rValue(beans[0]))
+		condSQL, condArgs, err = statement.genConds(beans[0])
+	} else {
+		condSQL, condArgs, err = builder.ToSQL(statement.cond)
+	}
 	if err != nil {
 		return "", nil, err
 	}