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package gorm
import (
"errors"
"fmt"
"reflect"
"strings"
)
// JoinTableHandlerInterface is an interface for how to handle many2many relations
type JoinTableHandlerInterface interface {
// initialize join table handler
Setup(relationship *Relationship, tableName string, source reflect.Type, destination reflect.Type)
// Table return join table's table name
Table(db *DB) string
// Add create relationship in join table for source and destination
Add(handler JoinTableHandlerInterface, db *DB, source interface{}, destination interface{}) error
// Delete delete relationship in join table for sources
Delete(handler JoinTableHandlerInterface, db *DB, sources ...interface{}) error
// JoinWith query with `Join` conditions
JoinWith(handler JoinTableHandlerInterface, db *DB, source interface{}) *DB
// SourceForeignKeys return source foreign keys
SourceForeignKeys() []JoinTableForeignKey
// DestinationForeignKeys return destination foreign keys
DestinationForeignKeys() []JoinTableForeignKey
}
// JoinTableForeignKey join table foreign key struct
type JoinTableForeignKey struct {
DBName string
AssociationDBName string
}
// JoinTableSource is a struct that contains model type and foreign keys
type JoinTableSource struct {
ModelType reflect.Type
ForeignKeys []JoinTableForeignKey
}
// JoinTableHandler default join table handler
type JoinTableHandler struct {
TableName string `sql:"-"`
Source JoinTableSource `sql:"-"`
Destination JoinTableSource `sql:"-"`
}
// SourceForeignKeys return source foreign keys
func (s *JoinTableHandler) SourceForeignKeys() []JoinTableForeignKey {
return s.Source.ForeignKeys
}
// DestinationForeignKeys return destination foreign keys
func (s *JoinTableHandler) DestinationForeignKeys() []JoinTableForeignKey {
return s.Destination.ForeignKeys
}
// Setup initialize a default join table handler
func (s *JoinTableHandler) Setup(relationship *Relationship, tableName string, source reflect.Type, destination reflect.Type) {
s.TableName = tableName
s.Source = JoinTableSource{ModelType: source}
s.Source.ForeignKeys = []JoinTableForeignKey{}
for idx, dbName := range relationship.ForeignFieldNames {
s.Source.ForeignKeys = append(s.Source.ForeignKeys, JoinTableForeignKey{
DBName: relationship.ForeignDBNames[idx],
AssociationDBName: dbName,
})
}
s.Destination = JoinTableSource{ModelType: destination}
s.Destination.ForeignKeys = []JoinTableForeignKey{}
for idx, dbName := range relationship.AssociationForeignFieldNames {
s.Destination.ForeignKeys = append(s.Destination.ForeignKeys, JoinTableForeignKey{
DBName: relationship.AssociationForeignDBNames[idx],
AssociationDBName: dbName,
})
}
}
// Table return join table's table name
func (s JoinTableHandler) Table(db *DB) string {
return DefaultTableNameHandler(db, s.TableName)
}
func (s JoinTableHandler) updateConditionMap(conditionMap map[string]interface{}, db *DB, joinTableSources []JoinTableSource, sources ...interface{}) {
for _, source := range sources {
scope := db.NewScope(source)
modelType := scope.GetModelStruct().ModelType
for _, joinTableSource := range joinTableSources {
if joinTableSource.ModelType == modelType {
for _, foreignKey := range joinTableSource.ForeignKeys {
if field, ok := scope.FieldByName(foreignKey.AssociationDBName); ok {
conditionMap[foreignKey.DBName] = field.Field.Interface()
}
}
break
}
}
}
}
// Add create relationship in join table for source and destination
func (s JoinTableHandler) Add(handler JoinTableHandlerInterface, db *DB, source interface{}, destination interface{}) error {
var (
scope = db.NewScope("")
conditionMap = map[string]interface{}{}
)
// Update condition map for source
s.updateConditionMap(conditionMap, db, []JoinTableSource{s.Source}, source)
// Update condition map for destination
s.updateConditionMap(conditionMap, db, []JoinTableSource{s.Destination}, destination)
var assignColumns, binVars, conditions []string
var values []interface{}
for key, value := range conditionMap {
assignColumns = append(assignColumns, scope.Quote(key))
binVars = append(binVars, `?`)
conditions = append(conditions, fmt.Sprintf("%v = ?", scope.Quote(key)))
values = append(values, value)
}
for _, value := range values {
values = append(values, value)
}
quotedTable := scope.Quote(handler.Table(db))
sql := fmt.Sprintf(
"INSERT INTO %v (%v) SELECT %v %v WHERE NOT EXISTS (SELECT * FROM %v WHERE %v)",
quotedTable,
strings.Join(assignColumns, ","),
strings.Join(binVars, ","),
scope.Dialect().SelectFromDummyTable(),
quotedTable,
strings.Join(conditions, " AND "),
)
return db.Exec(sql, values...).Error
}
// Delete delete relationship in join table for sources
func (s JoinTableHandler) Delete(handler JoinTableHandlerInterface, db *DB, sources ...interface{}) error {
var (
scope = db.NewScope(nil)
conditions []string
values []interface{}
conditionMap = map[string]interface{}{}
)
s.updateConditionMap(conditionMap, db, []JoinTableSource{s.Source, s.Destination}, sources...)
for key, value := range conditionMap {
conditions = append(conditions, fmt.Sprintf("%v = ?", scope.Quote(key)))
values = append(values, value)
}
return db.Table(handler.Table(db)).Where(strings.Join(conditions, " AND "), values...).Delete("").Error
}
// JoinWith query with `Join` conditions
func (s JoinTableHandler) JoinWith(handler JoinTableHandlerInterface, db *DB, source interface{}) *DB {
var (
scope = db.NewScope(source)
tableName = handler.Table(db)
quotedTableName = scope.Quote(tableName)
joinConditions []string
values []interface{}
)
if s.Source.ModelType == scope.GetModelStruct().ModelType {
destinationTableName := db.NewScope(reflect.New(s.Destination.ModelType).Interface()).QuotedTableName()
for _, foreignKey := range s.Destination.ForeignKeys {
joinConditions = append(joinConditions, fmt.Sprintf("%v.%v = %v.%v", quotedTableName, scope.Quote(foreignKey.DBName), destinationTableName, scope.Quote(foreignKey.AssociationDBName)))
}
var foreignDBNames []string
var foreignFieldNames []string
for _, foreignKey := range s.Source.ForeignKeys {
foreignDBNames = append(foreignDBNames, foreignKey.DBName)
if field, ok := scope.FieldByName(foreignKey.AssociationDBName); ok {
foreignFieldNames = append(foreignFieldNames, field.Name)
}
}
foreignFieldValues := scope.getColumnAsArray(foreignFieldNames, scope.Value)
var condString string
if len(foreignFieldValues) > 0 {
var quotedForeignDBNames []string
for _, dbName := range foreignDBNames {
quotedForeignDBNames = append(quotedForeignDBNames, tableName+"."+dbName)
}
condString = fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, quotedForeignDBNames), toQueryMarks(foreignFieldValues))
keys := scope.getColumnAsArray(foreignFieldNames, scope.Value)
values = append(values, toQueryValues(keys))
} else {
condString = fmt.Sprintf("1 <> 1")
}
return db.Joins(fmt.Sprintf("INNER JOIN %v ON %v", quotedTableName, strings.Join(joinConditions, " AND "))).
Where(condString, toQueryValues(foreignFieldValues)...)
}
db.Error = errors.New("wrong source type for join table handler")
return db
}