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delete.go
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delete.go
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/*
* Copyright (C) 2018 Dolan and Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dgman
import (
"bytes"
"context"
"github.com/dgraph-io/dgo/v200/protos/api"
"github.com/dgraph-io/dgo/v200"
"github.com/pkg/errors"
)
type Deleter struct {
ctx context.Context
tx *dgo.Txn
model interface{}
q *Query
commitNow bool
}
// Query defines the query portion other than the root function for deletion
func (d *Deleter) Query(query string, params ...interface{}) *Deleter {
d.q.query = parseQueryWithParams(query, params)
return d
}
// Filter defines a query filter, return predicates at the first depth
func (d *Deleter) Filter(filter string, params ...interface{}) *Deleter {
d.q.filter = parseQueryWithParams(filter, params)
return d
}
// UID returns the node with the specified uid
func (d *Deleter) UID(uid string) *Deleter {
d.q.uid = uid
return d
}
// All returns expands all predicates, with a depth parameter that specifies
// how deep should edges be expanded
func (d *Deleter) All(depthParam ...int) *Deleter {
d.q.All(depthParam...)
return d
}
// Vars specify the GraphQL variables to be passed on the query,
// by specifying the function definition of vars, and variable map.
// Example funcDef: getUserByEmail($email: string, $age: number)
func (d *Deleter) Vars(funcDef string, vars map[string]string) *Deleter {
d.q.paramString = funcDef
d.q.vars = vars
return d
}
// RootFunc modifies the dgraph query root function, if not set,
// the default is "type(NodeType)"
func (d *Deleter) RootFunc(rootFunc string) *Deleter {
d.q.rootFunc = rootFunc
return d
}
func (d *Deleter) First(n int) *Deleter {
d.q.first = n
return d
}
func (d *Deleter) Offset(n int) *Deleter {
d.q.offset = n
return d
}
func (d *Deleter) After(uid string) *Deleter {
d.q.after = uid
return d
}
func (d *Deleter) OrderAsc(clause string) *Deleter {
d.q.order = append(d.q.order, order{clause: clause})
return d
}
func (d *Deleter) OrderDesc(clause string) *Deleter {
d.q.order = append(d.q.order, order{descending: true, clause: clause})
return d
}
// Edge delete edges of a node of specified edge predicate, if no edgeUIDs specified,
// delete all edges
func (d *Deleter) Edge(uid, edgePredicate string, edgeUIDs ...string) error {
var buffer bytes.Buffer
buffer.WriteString(`{"uid": "`)
buffer.WriteString(uid)
buffer.WriteString(`", "`)
buffer.WriteString(edgePredicate)
buffer.WriteString(`": `)
if len(edgeUIDs) == 0 {
// if no uids specified, delete all edges
buffer.WriteString(`null`)
} else {
buffer.WriteByte('[')
for _, edgeUID := range edgeUIDs {
buffer.WriteString(`{"uid": "`)
buffer.WriteString(edgeUID)
buffer.WriteString(`"}`)
}
buffer.WriteByte(']')
}
buffer.WriteByte('}')
_, err := d.tx.Mutate(d.ctx, &api.Mutation{DeleteJson: buffer.Bytes(), CommitNow: d.commitNow})
return err
}
// Node deletes the first single root node from the query
// including edge nodes that may be specified on the query
func (d *Deleter) Node() (uids []string, err error) {
d.q.first = 1
result, err := d.q.executeQuery()
if err != nil {
return nil, errors.Wrap(err, "exec")
}
model := make(map[string]interface{})
if err := d.q.node(result, &model); err != nil {
return nil, errors.Wrap(err, "parse query")
}
traverseUIDs(&uids, model)
return uids, d.deleteUids(uids)
}
// Nodes deletes all nodes matching the delete query
// including edge nodes that may be specified on the query
func (d *Deleter) Nodes() (uids []string, err error) {
result, err := d.q.executeQuery()
if err != nil {
return nil, err
}
var model []map[string]interface{}
if err := d.q.nodes(result, &model); err != nil {
return nil, err
}
for _, m := range model {
traverseUIDs(&uids, m)
}
return uids, d.deleteUids(uids)
}
func (d *Deleter) deleteUids(uids []string) error {
uidsJSON := generateUidsJSON(uids)
_, err := d.tx.Mutate(d.ctx, &api.Mutation{
DeleteJson: uidsJSON,
CommitNow: d.commitNow,
})
return err
}
func generateUidsJSON(uids []string) []byte {
var b bytes.Buffer
b.WriteByte('[')
for i, uid := range uids {
b.WriteString(`{"uid":"`)
b.WriteString(uid)
b.WriteString(`"}`)
if i != len(uids)-1 {
b.WriteByte(',')
}
}
b.WriteByte(']')
return b.Bytes()
}
func traverseUIDs(uids *[]string, model map[string]interface{}) {
for predicate, val := range model {
switch v := val.(type) {
case []interface{}:
for _, node := range v {
if v2, ok := node.(map[string]interface{}); ok {
traverseUIDs(uids, v2)
}
}
case string:
if predicate == "uid" {
*uids = append(*uids, val.(string))
}
}
}
}
func (d *Deleter) String() string {
return d.q.String()
}