package bun import ( "context" "database/sql" "fmt" "reflect" "github.com/uptrace/bun/internal" "github.com/uptrace/bun/schema" ) type m2mModel struct { *sliceTableModel baseTable *schema.Table rel *schema.Relation baseValues map[internal.MapKey][]reflect.Value structKey []interface{} } var _ tableModel = (*m2mModel)(nil) func newM2MModel(j *relationJoin) *m2mModel { baseTable := j.BaseModel.Table() joinModel := j.JoinModel.(*sliceTableModel) baseValues := baseValues(joinModel, baseTable.PKs) if len(baseValues) == 0 { return nil } m := &m2mModel{ sliceTableModel: joinModel, baseTable: baseTable, rel: j.Relation, baseValues: baseValues, } if !m.sliceOfPtr { m.strct = reflect.New(m.table.Type).Elem() } return m } func (m *m2mModel) ScanRows(ctx context.Context, rows *sql.Rows) (int, error) { columns, err := rows.Columns() if err != nil { return 0, err } m.columns = columns dest := makeDest(m, len(columns)) var n int for rows.Next() { if m.sliceOfPtr { m.strct = reflect.New(m.table.Type).Elem() } else { m.strct.Set(m.table.ZeroValue) } m.structInited = false m.scanIndex = 0 m.structKey = m.structKey[:0] if err := rows.Scan(dest...); err != nil { return 0, err } if err := m.parkStruct(); err != nil { return 0, err } n++ } if err := rows.Err(); err != nil { return 0, err } return n, nil } func (m *m2mModel) Scan(src interface{}) error { column := m.columns[m.scanIndex] m.scanIndex++ field, ok := m.table.FieldMap[column] if !ok { return m.scanM2MColumn(column, src) } if err := field.ScanValue(m.strct, src); err != nil { return err } for _, fk := range m.rel.M2MBaseFields { if fk.Name == field.Name { m.structKey = append(m.structKey, field.Value(m.strct).Interface()) break } } return nil } func (m *m2mModel) scanM2MColumn(column string, src interface{}) error { for _, field := range m.rel.M2MBaseFields { if field.Name == column { dest := reflect.New(field.IndirectType).Elem() if err := field.Scan(dest, src); err != nil { return err } m.structKey = append(m.structKey, dest.Interface()) break } } _, err := m.scanColumn(column, src) return err } func (m *m2mModel) parkStruct() error { baseValues, ok := m.baseValues[internal.NewMapKey(m.structKey)] if !ok { return fmt.Errorf( "bun: m2m relation=%s does not have base %s with key=%q (check join conditions)", m.rel.Field.GoName, m.baseTable, m.structKey) } for _, v := range baseValues { if m.sliceOfPtr { v.Set(reflect.Append(v, m.strct.Addr())) } else { v.Set(reflect.Append(v, m.strct)) } } return nil }