Pg to bun (#148)

* start moving to bun

* changing more stuff

* more

* and yet more

* tests passing

* seems stable now

* more big changes

* small fix

* little fixes

vendor/github.com/uptrace/bun/model_table_m2m.go

@@ -0,0 +1,138 @@
+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 *join) *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
+}