122 lines
3.8 KiB
Go
122 lines
3.8 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 SingleResult methods when the operation that created the SingleResult did not return
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// 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 the operation resulted in an error, all
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// SingleResult methods will return that error. If the operation did not return any documents, all SingleResult methods
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// will return ErrNoDocuments.
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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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// NewSingleResultFromDocument creates a SingleResult with the provided error, registry, and an underlying Cursor pre-loaded with
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// the provided document, error and registry. If no registry is provided, bson.DefaultRegistry will be used. If an error distinct
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// from the one provided occurs during creation of the SingleResult, that error will be stored on the returned SingleResult.
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//
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// The document parameter must be a non-nil document.
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func NewSingleResultFromDocument(document interface{}, err error, registry *bsoncodec.Registry) *SingleResult {
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if document == nil {
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return &SingleResult{err: ErrNilDocument}
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}
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if registry == nil {
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registry = bson.DefaultRegistry
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}
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cur, createErr := NewCursorFromDocuments([]interface{}{document}, err, registry)
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if createErr != nil {
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return &SingleResult{err: createErr}
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}
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return &SingleResult{
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cur: cur,
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err: err,
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reg: registry,
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}
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}
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// Decode will unmarshal the document represented by this SingleResult into v. If there was an error from the operation
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// that created this SingleResult, that error will be returned. If the operation returned no documents, Decode will
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// return ErrNoDocuments.
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//
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// If the operation was successful and returned a document, Decode will return any errors from the unmarshalling process
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// without any modification. 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 the document represented by this SingleResult as a bson.Raw. If there was an error from the
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// operation that created this SingleResult, both the result and that error will be returned. If the operation returned
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// no documents, this will return (nil, ErrNoDocuments).
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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 returns the error from the operation that created this SingleResult. If the operation was successful but did not
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// return any documents, Err will return ErrNoDocuments. If the operation was successful and returned a document, Err
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// will return nil.
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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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