/
preload.go
343 lines (309 loc) · 11.6 KB
/
preload.go
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package callbacks
import (
"fmt"
"reflect"
"sort"
"strings"
"gorm.io/gorm"
"gorm.io/gorm/clause"
"gorm.io/gorm/schema"
"gorm.io/gorm/utils"
)
// parsePreloadMap extracts nested preloads. e.g.
//
// // schema has a "k0" relation and a "k7.k8" embedded relation
// parsePreloadMap(schema, map[string][]interface{}{
// clause.Associations: {"arg1"},
// "k1": {"arg2"},
// "k2.k3": {"arg3"},
// "k4.k5.k6": {"arg4"},
// })
// // preloadMap is
// map[string]map[string][]interface{}{
// "k0": {},
// "k7": {
// "k8": {},
// },
// "k1": {},
// "k2": {
// "k3": {"arg3"},
// },
// "k4": {
// "k5.k6": {"arg4"},
// },
// }
func parsePreloadMap(s *schema.Schema, preloads map[string][]interface{}) map[string]map[string][]interface{} {
preloadMap := map[string]map[string][]interface{}{}
setPreloadMap := func(name, value string, args []interface{}) {
if _, ok := preloadMap[name]; !ok {
preloadMap[name] = map[string][]interface{}{}
}
if value != "" {
preloadMap[name][value] = args
}
}
for name, args := range preloads {
preloadFields := strings.Split(name, ".")
value := strings.TrimPrefix(strings.TrimPrefix(name, preloadFields[0]), ".")
if preloadFields[0] == clause.Associations {
for _, relation := range s.Relationships.Relations {
if relation.Schema == s {
setPreloadMap(relation.Name, value, args)
}
}
for embedded, embeddedRelations := range s.Relationships.EmbeddedRelations {
for _, value := range embeddedValues(embeddedRelations) {
setPreloadMap(embedded, value, args)
}
}
} else {
setPreloadMap(preloadFields[0], value, args)
}
}
return preloadMap
}
func embeddedValues(embeddedRelations *schema.Relationships) []string {
if embeddedRelations == nil {
return nil
}
names := make([]string, 0, len(embeddedRelations.Relations)+len(embeddedRelations.EmbeddedRelations))
for _, relation := range embeddedRelations.Relations {
// skip first struct name
names = append(names, strings.Join(relation.Field.EmbeddedBindNames[1:], "."))
}
for _, relations := range embeddedRelations.EmbeddedRelations {
names = append(names, embeddedValues(relations)...)
}
return names
}
// preloadEntryPoint enters layer by layer. It will call real preload if it finds the right entry point.
// If the current relationship is embedded or joined, current query will be ignored.
//
//nolint:cyclop
func preloadEntryPoint(db *gorm.DB, joins []string, relationships *schema.Relationships, preloads map[string][]interface{}, associationsConds []interface{}) error {
preloadMap := parsePreloadMap(db.Statement.Schema, preloads)
// avoid random traversal of the map
preloadNames := make([]string, 0, len(preloadMap))
for key := range preloadMap {
preloadNames = append(preloadNames, key)
}
sort.Strings(preloadNames)
isJoined := func(name string) (joined bool, nestedJoins []string) {
for _, join := range joins {
if _, ok := relationships.Relations[join]; ok && name == join {
joined = true
continue
}
joinNames := strings.SplitN(join, ".", 2)
if len(joinNames) == 2 {
if _, ok := relationships.Relations[joinNames[0]]; ok && name == joinNames[0] {
joined = true
nestedJoins = append(nestedJoins, joinNames[1])
}
}
}
return joined, nestedJoins
}
for _, name := range preloadNames {
if relations := relationships.EmbeddedRelations[name]; relations != nil {
if err := preloadEntryPoint(db, joins, relations, preloadMap[name], associationsConds); err != nil {
return err
}
} else if rel := relationships.Relations[name]; rel != nil {
if joined, nestedJoins := isJoined(name); joined {
switch rv := db.Statement.ReflectValue; rv.Kind() {
case reflect.Slice, reflect.Array:
if rv.Len() > 0 {
reflectValue := rel.FieldSchema.MakeSlice().Elem()
reflectValue.SetLen(rv.Len())
for i := 0; i < rv.Len(); i++ {
frv := rel.Field.ReflectValueOf(db.Statement.Context, rv.Index(i))
if frv.Kind() != reflect.Ptr {
reflectValue.Index(i).Set(frv.Addr())
} else {
reflectValue.Index(i).Set(frv)
}
}
tx := preloadDB(db, reflectValue, reflectValue.Interface())
if err := preloadEntryPoint(tx, nestedJoins, &tx.Statement.Schema.Relationships, preloadMap[name], associationsConds); err != nil {
return err
}
}
case reflect.Struct:
reflectValue := rel.Field.ReflectValueOf(db.Statement.Context, rv)
tx := preloadDB(db, reflectValue, reflectValue.Interface())
if err := preloadEntryPoint(tx, nestedJoins, &tx.Statement.Schema.Relationships, preloadMap[name], associationsConds); err != nil {
return err
}
default:
return gorm.ErrInvalidData
}
} else {
tx := db.Table("").Session(&gorm.Session{Context: db.Statement.Context, SkipHooks: db.Statement.SkipHooks})
tx.Statement.ReflectValue = db.Statement.ReflectValue
tx.Statement.Unscoped = db.Statement.Unscoped
if err := preload(tx, rel, append(preloads[name], associationsConds...), preloadMap[name]); err != nil {
return err
}
}
} else {
return fmt.Errorf("%s: %w for schema %s", name, gorm.ErrUnsupportedRelation, db.Statement.Schema.Name)
}
}
return nil
}
func preloadDB(db *gorm.DB, reflectValue reflect.Value, dest interface{}) *gorm.DB {
tx := db.Session(&gorm.Session{Context: db.Statement.Context, NewDB: true, SkipHooks: db.Statement.SkipHooks, Initialized: true})
db.Statement.Settings.Range(func(k, v interface{}) bool {
tx.Statement.Settings.Store(k, v)
return true
})
if err := tx.Statement.Parse(dest); err != nil {
tx.AddError(err)
return tx
}
tx.Statement.ReflectValue = reflectValue
tx.Statement.Unscoped = db.Statement.Unscoped
return tx
}
func preload(tx *gorm.DB, rel *schema.Relationship, conds []interface{}, preloads map[string][]interface{}) error {
var (
reflectValue = tx.Statement.ReflectValue
relForeignKeys []string
relForeignFields []*schema.Field
foreignFields []*schema.Field
foreignValues [][]interface{}
identityMap = map[string][]reflect.Value{}
inlineConds []interface{}
)
if rel.JoinTable != nil {
var (
joinForeignFields = make([]*schema.Field, 0, len(rel.References))
joinRelForeignFields = make([]*schema.Field, 0, len(rel.References))
joinForeignKeys = make([]string, 0, len(rel.References))
)
for _, ref := range rel.References {
if ref.OwnPrimaryKey {
joinForeignKeys = append(joinForeignKeys, ref.ForeignKey.DBName)
joinForeignFields = append(joinForeignFields, ref.ForeignKey)
foreignFields = append(foreignFields, ref.PrimaryKey)
} else if ref.PrimaryValue != "" {
tx = tx.Where(clause.Eq{Column: ref.ForeignKey.DBName, Value: ref.PrimaryValue})
} else {
joinRelForeignFields = append(joinRelForeignFields, ref.ForeignKey)
relForeignKeys = append(relForeignKeys, ref.PrimaryKey.DBName)
relForeignFields = append(relForeignFields, ref.PrimaryKey)
}
}
joinIdentityMap, joinForeignValues := schema.GetIdentityFieldValuesMap(tx.Statement.Context, reflectValue, foreignFields)
if len(joinForeignValues) == 0 {
return nil
}
joinResults := rel.JoinTable.MakeSlice().Elem()
column, values := schema.ToQueryValues(clause.CurrentTable, joinForeignKeys, joinForeignValues)
if err := tx.Where(clause.IN{Column: column, Values: values}).Find(joinResults.Addr().Interface()).Error; err != nil {
return err
}
// convert join identity map to relation identity map
fieldValues := make([]interface{}, len(joinForeignFields))
joinFieldValues := make([]interface{}, len(joinRelForeignFields))
for i := 0; i < joinResults.Len(); i++ {
joinIndexValue := joinResults.Index(i)
for idx, field := range joinForeignFields {
fieldValues[idx], _ = field.ValueOf(tx.Statement.Context, joinIndexValue)
}
for idx, field := range joinRelForeignFields {
joinFieldValues[idx], _ = field.ValueOf(tx.Statement.Context, joinIndexValue)
}
if results, ok := joinIdentityMap[utils.ToStringKey(fieldValues...)]; ok {
joinKey := utils.ToStringKey(joinFieldValues...)
identityMap[joinKey] = append(identityMap[joinKey], results...)
}
}
_, foreignValues = schema.GetIdentityFieldValuesMap(tx.Statement.Context, joinResults, joinRelForeignFields)
} else {
for _, ref := range rel.References {
if ref.OwnPrimaryKey {
relForeignKeys = append(relForeignKeys, ref.ForeignKey.DBName)
relForeignFields = append(relForeignFields, ref.ForeignKey)
foreignFields = append(foreignFields, ref.PrimaryKey)
} else if ref.PrimaryValue != "" {
tx = tx.Where(clause.Eq{Column: ref.ForeignKey.DBName, Value: ref.PrimaryValue})
} else {
relForeignKeys = append(relForeignKeys, ref.PrimaryKey.DBName)
relForeignFields = append(relForeignFields, ref.PrimaryKey)
foreignFields = append(foreignFields, ref.ForeignKey)
}
}
identityMap, foreignValues = schema.GetIdentityFieldValuesMap(tx.Statement.Context, reflectValue, foreignFields)
if len(foreignValues) == 0 {
return nil
}
}
// nested preload
for p, pvs := range preloads {
tx = tx.Preload(p, pvs...)
}
reflectResults := rel.FieldSchema.MakeSlice().Elem()
column, values := schema.ToQueryValues(clause.CurrentTable, relForeignKeys, foreignValues)
if len(values) != 0 {
for _, cond := range conds {
if fc, ok := cond.(func(*gorm.DB) *gorm.DB); ok {
tx = fc(tx)
} else {
inlineConds = append(inlineConds, cond)
}
}
if err := tx.Where(clause.IN{Column: column, Values: values}).Find(reflectResults.Addr().Interface(), inlineConds...).Error; err != nil {
return err
}
}
fieldValues := make([]interface{}, len(relForeignFields))
// clean up old values before preloading
switch reflectValue.Kind() {
case reflect.Struct:
switch rel.Type {
case schema.HasMany, schema.Many2Many:
tx.AddError(rel.Field.Set(tx.Statement.Context, reflectValue, reflect.MakeSlice(rel.Field.IndirectFieldType, 0, 10).Interface()))
default:
tx.AddError(rel.Field.Set(tx.Statement.Context, reflectValue, reflect.New(rel.Field.FieldType).Interface()))
}
case reflect.Slice, reflect.Array:
for i := 0; i < reflectValue.Len(); i++ {
switch rel.Type {
case schema.HasMany, schema.Many2Many:
tx.AddError(rel.Field.Set(tx.Statement.Context, reflectValue.Index(i), reflect.MakeSlice(rel.Field.IndirectFieldType, 0, 10).Interface()))
default:
tx.AddError(rel.Field.Set(tx.Statement.Context, reflectValue.Index(i), reflect.New(rel.Field.FieldType).Interface()))
}
}
}
for i := 0; i < reflectResults.Len(); i++ {
elem := reflectResults.Index(i)
for idx, field := range relForeignFields {
fieldValues[idx], _ = field.ValueOf(tx.Statement.Context, elem)
}
datas, ok := identityMap[utils.ToStringKey(fieldValues...)]
if !ok {
return fmt.Errorf("failed to assign association %#v, make sure foreign fields exists", elem.Interface())
}
for _, data := range datas {
reflectFieldValue := rel.Field.ReflectValueOf(tx.Statement.Context, data)
if reflectFieldValue.Kind() == reflect.Ptr && reflectFieldValue.IsNil() {
reflectFieldValue.Set(reflect.New(rel.Field.FieldType.Elem()))
}
reflectFieldValue = reflect.Indirect(reflectFieldValue)
switch reflectFieldValue.Kind() {
case reflect.Struct:
tx.AddError(rel.Field.Set(tx.Statement.Context, data, elem.Interface()))
case reflect.Slice, reflect.Array:
if reflectFieldValue.Type().Elem().Kind() == reflect.Ptr {
tx.AddError(rel.Field.Set(tx.Statement.Context, data, reflect.Append(reflectFieldValue, elem).Interface()))
} else {
tx.AddError(rel.Field.Set(tx.Statement.Context, data, reflect.Append(reflectFieldValue, elem.Elem()).Interface()))
}
}
}
}
return tx.Error
}