Don Newton | 379ae25 | 2019-04-01 12:17:06 -0400 | [diff] [blame^] | 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 command |
| 8 | |
| 9 | import ( |
| 10 | "context" |
| 11 | "errors" |
| 12 | |
| 13 | "github.com/mongodb/mongo-go-driver/bson/bsontype" |
| 14 | "github.com/mongodb/mongo-go-driver/mongo/readconcern" |
| 15 | "github.com/mongodb/mongo-go-driver/mongo/readpref" |
| 16 | "github.com/mongodb/mongo-go-driver/x/bsonx" |
| 17 | "github.com/mongodb/mongo-go-driver/x/mongo/driver/session" |
| 18 | "github.com/mongodb/mongo-go-driver/x/network/description" |
| 19 | "github.com/mongodb/mongo-go-driver/x/network/wiremessage" |
| 20 | ) |
| 21 | |
| 22 | // CountDocuments represents the CountDocuments command. |
| 23 | // |
| 24 | // The countDocuments command counts how many documents in a collection match the given query. |
| 25 | type CountDocuments struct { |
| 26 | NS Namespace |
| 27 | Pipeline bsonx.Arr |
| 28 | Opts []bsonx.Elem |
| 29 | ReadPref *readpref.ReadPref |
| 30 | ReadConcern *readconcern.ReadConcern |
| 31 | Clock *session.ClusterClock |
| 32 | Session *session.Client |
| 33 | |
| 34 | result int64 |
| 35 | err error |
| 36 | } |
| 37 | |
| 38 | // Encode will encode this command into a wire message for the given server description. |
| 39 | func (c *CountDocuments) Encode(desc description.SelectedServer) (wiremessage.WireMessage, error) { |
| 40 | if err := c.NS.Validate(); err != nil { |
| 41 | return nil, err |
| 42 | } |
| 43 | command := bsonx.Doc{{"aggregate", bsonx.String(c.NS.Collection)}, {"pipeline", bsonx.Array(c.Pipeline)}} |
| 44 | |
| 45 | command = append(command, bsonx.Elem{"cursor", bsonx.Document(bsonx.Doc{})}) |
| 46 | command = append(command, c.Opts...) |
| 47 | |
| 48 | return (&Read{DB: c.NS.DB, ReadPref: c.ReadPref, Command: command}).Encode(desc) |
| 49 | } |
| 50 | |
| 51 | // Decode will decode the wire message using the provided server description. Errors during decoding |
| 52 | // are deferred until either the Result or Err methods are called. |
| 53 | func (c *CountDocuments) Decode(ctx context.Context, desc description.SelectedServer, wm wiremessage.WireMessage) *CountDocuments { |
| 54 | rdr, err := (&Read{}).Decode(desc, wm).Result() |
| 55 | if err != nil { |
| 56 | c.err = err |
| 57 | return c |
| 58 | } |
| 59 | |
| 60 | cursor, err := rdr.LookupErr("cursor") |
| 61 | if err != nil || cursor.Type != bsontype.EmbeddedDocument { |
| 62 | c.err = errors.New("Invalid response from server, no 'cursor' field") |
| 63 | return c |
| 64 | } |
| 65 | batch, err := cursor.Document().LookupErr("firstBatch") |
| 66 | if err != nil || batch.Type != bsontype.Array { |
| 67 | c.err = errors.New("Invalid response from server, no 'firstBatch' field") |
| 68 | return c |
| 69 | } |
| 70 | |
| 71 | elem, err := batch.Array().IndexErr(0) |
| 72 | if err != nil || elem.Value().Type != bsontype.EmbeddedDocument { |
| 73 | c.result = 0 |
| 74 | return c |
| 75 | } |
| 76 | |
| 77 | val, err := elem.Value().Document().LookupErr("n") |
| 78 | if err != nil { |
| 79 | c.err = errors.New("Invalid response from server, no 'n' field") |
| 80 | return c |
| 81 | } |
| 82 | |
| 83 | switch val.Type { |
| 84 | case bsontype.Int32: |
| 85 | c.result = int64(val.Int32()) |
| 86 | case bsontype.Int64: |
| 87 | c.result = val.Int64() |
| 88 | default: |
| 89 | c.err = errors.New("Invalid response from server, value field is not a number") |
| 90 | } |
| 91 | |
| 92 | return c |
| 93 | } |
| 94 | |
| 95 | // Result returns the result of a decoded wire message and server description. |
| 96 | func (c *CountDocuments) Result() (int64, error) { |
| 97 | if c.err != nil { |
| 98 | return 0, c.err |
| 99 | } |
| 100 | return c.result, nil |
| 101 | } |
| 102 | |
| 103 | // Err returns the error set on this command. |
| 104 | func (c *CountDocuments) Err() error { return c.err } |
| 105 | |
| 106 | // RoundTrip handles the execution of this command using the provided wiremessage.ReadWriter. |
| 107 | func (c *CountDocuments) RoundTrip(ctx context.Context, desc description.SelectedServer, rw wiremessage.ReadWriter) (int64, error) { |
| 108 | wm, err := c.Encode(desc) |
| 109 | if err != nil { |
| 110 | return 0, err |
| 111 | } |
| 112 | |
| 113 | err = rw.WriteWireMessage(ctx, wm) |
| 114 | if err != nil { |
| 115 | return 0, err |
| 116 | } |
| 117 | wm, err = rw.ReadWireMessage(ctx) |
| 118 | if err != nil { |
| 119 | return 0, err |
| 120 | } |
| 121 | return c.Decode(ctx, desc, wm).Result() |
| 122 | } |