| // Copyright (C) MongoDB, Inc. 2017-present. |
| // |
| // 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 |
| |
| package command |
| |
| import ( |
| "context" |
| "errors" |
| |
| "github.com/mongodb/mongo-go-driver/bson" |
| "github.com/mongodb/mongo-go-driver/mongo/readconcern" |
| "github.com/mongodb/mongo-go-driver/mongo/readpref" |
| "github.com/mongodb/mongo-go-driver/x/bsonx" |
| "github.com/mongodb/mongo-go-driver/x/bsonx/bsoncore" |
| "github.com/mongodb/mongo-go-driver/x/mongo/driver/session" |
| "github.com/mongodb/mongo-go-driver/x/network/description" |
| "github.com/mongodb/mongo-go-driver/x/network/wiremessage" |
| ) |
| |
| // Count represents the count command. |
| // |
| // The count command counts how many documents in a collection match the given query. |
| type Count struct { |
| NS Namespace |
| Query bsonx.Doc |
| Opts []bsonx.Elem |
| ReadPref *readpref.ReadPref |
| ReadConcern *readconcern.ReadConcern |
| Clock *session.ClusterClock |
| Session *session.Client |
| |
| result int64 |
| err error |
| } |
| |
| // Encode will encode this command into a wire message for the given server description. |
| func (c *Count) Encode(desc description.SelectedServer) (wiremessage.WireMessage, error) { |
| cmd, err := c.encode(desc) |
| if err != nil { |
| return nil, err |
| } |
| |
| return cmd.Encode(desc) |
| } |
| |
| func (c *Count) encode(desc description.SelectedServer) (*Read, error) { |
| if err := c.NS.Validate(); err != nil { |
| return nil, err |
| } |
| |
| command := bsonx.Doc{{"count", bsonx.String(c.NS.Collection)}, {"query", bsonx.Document(c.Query)}} |
| command = append(command, c.Opts...) |
| |
| return &Read{ |
| Clock: c.Clock, |
| DB: c.NS.DB, |
| ReadPref: c.ReadPref, |
| Command: command, |
| ReadConcern: c.ReadConcern, |
| Session: c.Session, |
| }, nil |
| } |
| |
| // Decode will decode the wire message using the provided server description. Errors during decoding |
| // are deferred until either the Result or Err methods are called. |
| func (c *Count) Decode(desc description.SelectedServer, wm wiremessage.WireMessage) *Count { |
| rdr, err := (&Read{}).Decode(desc, wm).Result() |
| if err != nil { |
| c.err = err |
| return c |
| } |
| |
| return c.decode(desc, rdr) |
| } |
| |
| func (c *Count) decode(desc description.SelectedServer, rdr bson.Raw) *Count { |
| val, err := rdr.LookupErr("n") |
| switch { |
| case err == bsoncore.ErrElementNotFound: |
| c.err = errors.New("invalid response from server, no 'n' field") |
| return c |
| case err != nil: |
| c.err = err |
| return c |
| } |
| |
| switch val.Type { |
| case bson.TypeInt32: |
| c.result = int64(val.Int32()) |
| case bson.TypeInt64: |
| c.result = val.Int64() |
| case bson.TypeDouble: |
| c.result = int64(val.Double()) |
| default: |
| c.err = errors.New("invalid response from server, value field is not a number") |
| } |
| |
| return c |
| } |
| |
| // Result returns the result of a decoded wire message and server description. |
| func (c *Count) Result() (int64, error) { |
| if c.err != nil { |
| return 0, c.err |
| } |
| return c.result, nil |
| } |
| |
| // Err returns the error set on this command. |
| func (c *Count) Err() error { return c.err } |
| |
| // RoundTrip handles the execution of this command using the provided wiremessage.ReadWriter. |
| func (c *Count) RoundTrip(ctx context.Context, desc description.SelectedServer, rw wiremessage.ReadWriter) (int64, error) { |
| cmd, err := c.encode(desc) |
| if err != nil { |
| return 0, err |
| } |
| |
| rdr, err := cmd.RoundTrip(ctx, desc, rw) |
| if err != nil { |
| return 0, err |
| } |
| |
| return c.decode(desc, rdr).Result() |
| } |