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94 lines
2.5 KiB
Go
94 lines
2.5 KiB
Go
// Copyright (C) MongoDB, Inc. 2017-present.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package mongo
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import (
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"context"
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"errors"
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"go.mongodb.org/mongo-driver/bson"
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"go.mongodb.org/mongo-driver/bson/bsoncodec"
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)
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// ErrNoDocuments is returned by Decode when an operation that returns a
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// SingleResult doesn't return any documents.
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var ErrNoDocuments = errors.New("mongo: no documents in result")
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// SingleResult represents a single document returned from an operation. If
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// the operation returned an error, the Err method of SingleResult will
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// return that error.
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type SingleResult struct {
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err error
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cur *Cursor
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rdr bson.Raw
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reg *bsoncodec.Registry
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}
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// Decode will attempt to decode the first document into v. If there was an
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// error from the operation that created this SingleResult then the error
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// will be returned. If there were no returned documents, ErrNoDocuments is
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// returned. If v is nil or is a typed nil, an error will be returned.
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func (sr *SingleResult) Decode(v interface{}) error {
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if sr.err != nil {
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return sr.err
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}
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if sr.reg == nil {
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return bson.ErrNilRegistry
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}
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if sr.err = sr.setRdrContents(); sr.err != nil {
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return sr.err
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}
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return bson.UnmarshalWithRegistry(sr.reg, sr.rdr, v)
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}
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// DecodeBytes will return a copy of the document as a bson.Raw. If there was an
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// error from the operation that created this SingleResult then the error
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// will be returned along with the result. If there were no returned documents, ErrNoDocuments is
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// returned.
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func (sr *SingleResult) DecodeBytes() (bson.Raw, error) {
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if sr.err != nil {
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return sr.rdr, sr.err
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}
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if sr.err = sr.setRdrContents(); sr.err != nil {
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return nil, sr.err
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}
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return sr.rdr, nil
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}
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// setRdrContents will set the contents of rdr by iterating the underlying cursor if necessary.
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func (sr *SingleResult) setRdrContents() error {
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switch {
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case sr.err != nil:
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return sr.err
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case sr.rdr != nil:
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return nil
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case sr.cur != nil:
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defer sr.cur.Close(context.TODO())
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if !sr.cur.Next(context.TODO()) {
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if err := sr.cur.Err(); err != nil {
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return err
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}
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return ErrNoDocuments
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}
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sr.rdr = sr.cur.Current
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return nil
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}
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return ErrNoDocuments
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}
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// Err will return the error from the operation that created this SingleResult.
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// If there was no error, nil is returned.
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func (sr *SingleResult) Err() error {
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sr.err = sr.setRdrContents()
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return sr.err
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}
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