diff --git a/engine.go b/engine.go index 65d2f095..bb490125 100644 --- a/engine.go +++ b/engine.go @@ -45,6 +45,14 @@ type dialect interface { GetIndexes(tableName string) (map[string]*Index, error) } +type Iterator struct { + session *Session + stmt *sql.Stmt + rows *sql.Rows + fields []string + beanType reflect.Type +} + type PK []interface{} // Engine is the major struct of xorm, it means a database manager. @@ -933,6 +941,13 @@ func (engine *Engine) Iterate(bean interface{}, fun IterFunc) error { return session.Iterate(bean, fun) } +// Similar to Iterate(), return a forward Iterator object for iterating record by record, bean's non-empty fields +// are conditions. +func (engine *Engine) Scroll(bean interface{}) (*Iterator, error) { + session := engine.NewSession() + return session.Scroll(bean) +} + // Count counts the records. bean's non-empty fields // are conditions. func (engine *Engine) Count(bean interface{}) (int64, error) { diff --git a/iterator.go b/iterator.go new file mode 100644 index 00000000..4841d9df --- /dev/null +++ b/iterator.go @@ -0,0 +1,88 @@ +package xorm + +import ( + "database/sql" + "reflect" +) + +func newIterator(session *Session, bean interface{}) (*Iterator, error) { + iterator := new(Iterator) + iterator.session = session + iterator.beanType = reflect.Indirect(reflect.ValueOf(bean)).Type() + + err := iterator.session.newDb() + if err != nil { + return nil, err + } + + defer iterator.session.Statement.Init() + + var sql string + var args []interface{} + iterator.session.Statement.RefTable = iterator.session.Engine.autoMap(bean) + if iterator.session.Statement.RawSQL == "" { + sql, args = iterator.session.Statement.genGetSql(bean) + } else { + sql = iterator.session.Statement.RawSQL + args = iterator.session.Statement.RawParams + } + + for _, filter := range iterator.session.Engine.Filters { + sql = filter.Do(sql, session) + } + + iterator.session.Engine.LogSQL(sql) + iterator.session.Engine.LogSQL(args) + + iterator.stmt, err = iterator.session.Db.Prepare(sql) + if err != nil { + defer iterator.Close() + return nil, err + } + + iterator.rows, err = iterator.stmt.Query(args...) + if err != nil { + defer iterator.Close() + return nil, err + } + + iterator.fields, err = iterator.rows.Columns() + if err != nil { + defer iterator.Close() + return nil, err + } + + return iterator, nil +} + +func (iterator *Iterator) NextReuse(bean interface{}) (interface{}, error) { + if iterator.rows != nil && iterator.rows.Next() { + result, err := row2map(iterator.rows, iterator.fields) // !nashtsai! TODO remove row2map then scanMapIntoStruct conversation for better performance + if err == nil { + err = iterator.session.scanMapIntoStruct(bean, result) + } + if err == nil { + return bean, nil + } else { + return nil, err + } + } + return nil, sql.ErrNoRows +} + +func (iterator *Iterator) Next() (interface{}, error) { + b := reflect.New(iterator.beanType).Interface() + return iterator.NextReuse(b) +} + +func (iterator *Iterator) Close() { + if iterator.session.IsAutoClose { + defer iterator.session.Close() + } + if iterator.stmt != nil { + defer iterator.stmt.Close() + } + if iterator.rows != nil { + defer iterator.rows.Close() + } +} diff --git a/session.go b/session.go index 106fb0c5..651a280c 100644 --- a/session.go +++ b/session.go @@ -818,69 +818,34 @@ func (session *Session) cacheFind(t reflect.Type, sql string, rowsSlicePtr inter // IterFunc only use by Iterate type IterFunc func(idx int, bean interface{}) error +// Similar to Iterate(), return a forward Iterator object for iterating record by record, bean's non-empty fields +// are conditions. +func (session *Session) Scroll(bean interface{}) (*Iterator, error) { + return newIterator(session, bean) +} + // Iterate record by record handle records from table, condiBeans's non-empty fields // are conditions. beans could be []Struct, []*Struct, map[int64]Struct // map[int64]*Struct func (session *Session) Iterate(bean interface{}, fun IterFunc) error { - err := session.newDb() + + iterator, err := session.Scroll(bean) if err != nil { return err - } - - defer session.Statement.Init() - if session.IsAutoClose { - defer session.Close() - } - - var sql string - var args []interface{} - session.Statement.RefTable = session.Engine.autoMap(bean) - if session.Statement.RawSQL == "" { - sql, args = session.Statement.genGetSql(bean) } else { - sql = session.Statement.RawSQL - args = session.Statement.RawParams - } - - for _, filter := range session.Engine.Filters { - sql = filter.Do(sql, session) - } - - session.Engine.LogSQL(sql) - session.Engine.LogSQL(args) - - s, err := session.Db.Prepare(sql) - if err != nil { - return err - } - defer s.Close() - rows, err := s.Query(args...) - if err != nil { - return err - } - defer rows.Close() - - fields, err := rows.Columns() - if err != nil { - return err - } - t := reflect.Indirect(reflect.ValueOf(bean)).Type() - b := reflect.New(t).Interface() - i := 0 - for rows.Next() { - result, err := row2map(rows, fields) - if err == nil { - err = session.scanMapIntoStruct(b, result) - } - if err == nil { + defer iterator.Close() + //b := reflect.New(iterator.beanType).Interface() + i := 0 + for b, err := iterator.Next(); err != nil; b, err = iterator.Next() { err = fun(i, b) - i = i + 1 - } - if err != nil { - return err + if err != nil { + return err + } + i++ + b, err = iterator.Next() } + return err } - return nil }