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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
}
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