add comments

pkg/datastore/datastore.go

@@ -6,22 +6,27 @@ import (
 	"github.com/mayswind/lab/pkg/errs"
 )
 
+// DataStore represents a data storage containing a series of database shards
 type DataStore struct {
 	databases []*Database
 }
 
+// Choose returns a database instance by sharding key
 func (s *DataStore) Choose(key int64) *Database {
 	return s.databases[0]
 }
 
+// Query returns a new database session in a specific database by sharding key
 func (s *DataStore) Query(key int64) *xorm.Session {
 	return s.Choose(key).NewSession()
 }
 
+// DoTransaction runs a new database transaction in a specific database by sharding key
 func (s *DataStore) DoTransaction(key int64, fn func(sess *xorm.Session) error) (err error) {
 	return s.Choose(key).DoTransaction(fn)
 }
 
+// SyncStructs updates database structs by database models
 func (s *DataStore) SyncStructs(beans ...interface{}) error {
 	var err error
 
@@ -36,6 +41,7 @@ func (s *DataStore) SyncStructs(beans ...interface{}) error {
 	return err
 }
 
+// NewDataStore returns a new data storage by a series of database
 func NewDataStore(databases ...*Database) (*DataStore, error) {
 	if len(databases) < 1 {
 		return nil, errs.ErrDatabaseIsNull