github.com/mdaxf/iac@v0.0.0-20240519030858-58a061660378/vendor_skip/go.mongodb.org/mongo-driver/mongo/single_result.go (about)

     1  // Copyright (C) MongoDB, Inc. 2017-present.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License"); you may
     4  // not use this file except in compliance with the License. You may obtain
     5  // a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
     6  
     7  package mongo
     8  
     9  import (
    10  	"context"
    11  	"errors"
    12  	"fmt"
    13  
    14  	"go.mongodb.org/mongo-driver/bson"
    15  	"go.mongodb.org/mongo-driver/bson/bsoncodec"
    16  	"go.mongodb.org/mongo-driver/mongo/options"
    17  )
    18  
    19  // ErrNoDocuments is returned by SingleResult methods when the operation that created the SingleResult did not return
    20  // any documents.
    21  var ErrNoDocuments = errors.New("mongo: no documents in result")
    22  
    23  // SingleResult represents a single document returned from an operation. If the operation resulted in an error, all
    24  // SingleResult methods will return that error. If the operation did not return any documents, all SingleResult methods
    25  // will return ErrNoDocuments.
    26  type SingleResult struct {
    27  	ctx      context.Context
    28  	err      error
    29  	cur      *Cursor
    30  	rdr      bson.Raw
    31  	bsonOpts *options.BSONOptions
    32  	reg      *bsoncodec.Registry
    33  }
    34  
    35  // NewSingleResultFromDocument creates a SingleResult with the provided error, registry, and an underlying Cursor pre-loaded with
    36  // the provided document, error and registry. If no registry is provided, bson.DefaultRegistry will be used. If an error distinct
    37  // from the one provided occurs during creation of the SingleResult, that error will be stored on the returned SingleResult.
    38  //
    39  // The document parameter must be a non-nil document.
    40  func NewSingleResultFromDocument(document interface{}, err error, registry *bsoncodec.Registry) *SingleResult {
    41  	if document == nil {
    42  		return &SingleResult{err: ErrNilDocument}
    43  	}
    44  	if registry == nil {
    45  		registry = bson.DefaultRegistry
    46  	}
    47  
    48  	cur, createErr := NewCursorFromDocuments([]interface{}{document}, err, registry)
    49  	if createErr != nil {
    50  		return &SingleResult{err: createErr}
    51  	}
    52  
    53  	return &SingleResult{
    54  		cur: cur,
    55  		err: err,
    56  		reg: registry,
    57  	}
    58  }
    59  
    60  // Decode will unmarshal the document represented by this SingleResult into v. If there was an error from the operation
    61  // that created this SingleResult, that error will be returned. If the operation returned no documents, Decode will
    62  // return ErrNoDocuments.
    63  //
    64  // If the operation was successful and returned a document, Decode will return any errors from the unmarshalling process
    65  // without any modification. If v is nil or is a typed nil, an error will be returned.
    66  func (sr *SingleResult) Decode(v interface{}) error {
    67  	if sr.err != nil {
    68  		return sr.err
    69  	}
    70  	if sr.reg == nil {
    71  		return bson.ErrNilRegistry
    72  	}
    73  
    74  	if sr.err = sr.setRdrContents(); sr.err != nil {
    75  		return sr.err
    76  	}
    77  
    78  	dec, err := getDecoder(sr.rdr, sr.bsonOpts, sr.reg)
    79  	if err != nil {
    80  		return fmt.Errorf("error configuring BSON decoder: %w", err)
    81  	}
    82  
    83  	return dec.Decode(v)
    84  }
    85  
    86  // DecodeBytes will return the document represented by this SingleResult as a bson.Raw. If there was an error from the
    87  // operation that created this SingleResult, both the result and that error will be returned. If the operation returned
    88  // no documents, this will return (nil, ErrNoDocuments).
    89  func (sr *SingleResult) DecodeBytes() (bson.Raw, error) {
    90  	if sr.err != nil {
    91  		return sr.rdr, sr.err
    92  	}
    93  
    94  	if sr.err = sr.setRdrContents(); sr.err != nil {
    95  		return nil, sr.err
    96  	}
    97  	return sr.rdr, nil
    98  }
    99  
   100  // setRdrContents will set the contents of rdr by iterating the underlying cursor if necessary.
   101  func (sr *SingleResult) setRdrContents() error {
   102  	switch {
   103  	case sr.err != nil:
   104  		return sr.err
   105  	case sr.rdr != nil:
   106  		return nil
   107  	case sr.cur != nil:
   108  		defer sr.cur.Close(sr.ctx)
   109  
   110  		if !sr.cur.Next(sr.ctx) {
   111  			if err := sr.cur.Err(); err != nil {
   112  				return err
   113  			}
   114  
   115  			return ErrNoDocuments
   116  		}
   117  		sr.rdr = sr.cur.Current
   118  		return nil
   119  	}
   120  
   121  	return ErrNoDocuments
   122  }
   123  
   124  // Err provides a way to check for query errors without calling Decode. Err returns the error, if
   125  // any, that was encountered while running the operation. If the operation was successful but did
   126  // not return any documents, Err returns ErrNoDocuments. If this error is not nil, this error will
   127  // also be returned from Decode.
   128  func (sr *SingleResult) Err() error {
   129  	sr.err = sr.setRdrContents()
   130  
   131  	return sr.err
   132  }