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May 26, 2017

docs docs

MongoDB Go Driver

The MongoDB supported driver for Go.



Requirements

  • Go 1.10 or higher if using the driver as a dependency. Go 1.16 or higher if building the driver yourself. We aim to support the latest supported versions of go.
  • MongoDB 2.6 and higher.

Installation

The recommended way to get started using the MongoDB Go driver is by using go modules to install the dependency in your project. This can be done either by importing packages from go.mongodb.org/mongo-driver and having the build step install the dependency or by explicitly running

go get go.mongodb.org/mongo-driver/mongo

When using a version of Go that does not support modules, the driver can be installed using dep by running

dep ensure -add "go.mongodb.org/mongo-driver/mongo"

Usage

To get started with the driver, import the mongo package and create a mongo.Client with the Connect function:

import (
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
    "go.mongodb.org/mongo-driver/mongo/readpref"
)

ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://localhost:27017"))

Make sure to defer a call to Disconnect after instantiating your client:

defer func() {
    if err = client.Disconnect(ctx); err != nil {
        panic(err)
    }
}()

For more advanced configuration and authentication, see the documentation for mongo.Connect.

Calling Connect does not block for server discovery. If you wish to know if a MongoDB server has been found and connected to, use the Ping method:

ctx, cancel = context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()
err = client.Ping(ctx, readpref.Primary())

To insert a document into a collection, first retrieve a Database and then Collection instance from the Client:

collection := client.Database("testing").Collection("numbers")

The Collection instance can then be used to insert documents:

ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
res, err := collection.InsertOne(ctx, bson.D{{"name", "pi"}, {"value", 3.14159}})
id := res.InsertedID

To use bson.D, you will need to add "go.mongodb.org/mongo-driver/bson" to your imports.

Your import statement should now look like this:

import (
    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
    "go.mongodb.org/mongo-driver/mongo/readpref"
)

Several query methods return a cursor, which can be used like this:

ctx, cancel = context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()
cur, err := collection.Find(ctx, bson.D{})
if err != nil { log.Fatal(err) }
defer cur.Close(ctx)
for cur.Next(ctx) {
    var result bson.D
    err := cur.Decode(&result)
    if err != nil { log.Fatal(err) }
    // do something with result....
}
if err := cur.Err(); err != nil {
    log.Fatal(err)
}

For methods that return a single item, a SingleResult instance is returned:

var result struct {
    Value float64
}
filter := bson.D{{"name", "pi"}}
ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
err = collection.FindOne(ctx, filter).Decode(&result)
if err == mongo.ErrNoDocuments {
    // Do something when no record was found
    fmt.Println("record does not exist")
} else if err != nil {
    log.Fatal(err)
}
// Do something with result...

Additional examples and documentation can be found under the examples directory and on the MongoDB Documentation website.


Feedback

For help with the driver, please post in the MongoDB Community Forums.

New features and bugs can be reported on jira: https://jira.mongodb.org/browse/GODRIVER


Testing / Development

The driver tests can be run against several database configurations. The most simple configuration is a standalone mongod with no auth, no ssl, and no compression. To run these basic driver tests, make sure a standalone MongoDB server instance is running at localhost:27017. To run the tests, you can run make (on Windows, run nmake). This will run coverage, run go-lint, run go-vet, and build the examples.

Testing Different Topologies

To test a replica set or sharded cluster, set MONGODB_URI="<connection-string>" for the make command. For example, for a local replica set named rs1 comprised of three nodes on ports 27017, 27018, and 27019:

MONGODB_URI="mongodb://localhost:27017,localhost:27018,localhost:27019/?replicaSet=rs1" make

Testing Auth and TLS

To test authentication and TLS, first set up a MongoDB cluster with auth and TLS configured. Testing authentication requires a user with the root role on the admin database. Here is an example command that would run a mongod with TLS correctly configured for tests. Either set or replace PATH_TO_SERVER_KEY_FILE and PATH_TO_CA_FILE with paths to their respective files:

mongod \
--auth \
--tlsMode requireTLS \
--tlsCertificateKeyFile $PATH_TO_SERVER_KEY_FILE \
--tlsCAFile $PATH_TO_CA_FILE \
--tlsAllowInvalidCertificates

To run the tests with make, set:

  • MONGO_GO_DRIVER_CA_FILE to the location of the CA file used by the database
  • MONGO_GO_DRIVER_KEY_FILE to the location of the client key file
  • MONGO_GO_DRIVER_PKCS8_ENCRYPTED_KEY_FILE to the location of the pkcs8 client key file encrypted with the password string: password
  • MONGO_GO_DRIVER_PKCS8_UNENCRYPTED_KEY_FILE to the location of the unencrypted pkcs8 key file
  • MONGODB_URI to the connection string of the server
  • AUTH=auth
  • SSL=ssl

For example:

AUTH=auth SSL=ssl \
MONGO_GO_DRIVER_CA_FILE=$PATH_TO_CA_FILE \
MONGO_GO_DRIVER_KEY_FILE=$PATH_TO_CLIENT_KEY_FILE \
MONGO_GO_DRIVER_PKCS8_ENCRYPTED_KEY_FILE=$PATH_TO_ENCRYPTED_KEY_FILE \
MONGO_GO_DRIVER_PKCS8_UNENCRYPTED_KEY_FILE=$PATH_TO_UNENCRYPTED_KEY_FILE \
MONGODB_URI="mongodb://user:password@localhost:27017/?authSource=admin" \
make

Notes:

  • The --tlsAllowInvalidCertificates flag is required on the server for the test suite to work correctly.
  • The test suite requires the auth database to be set with ?authSource=admin, not /admin.

Testing Compression

The MongoDB Go Driver supports wire protocol compression using Snappy, zLib, or zstd. To run tests with wire protocol compression, set MONGO_GO_DRIVER_COMPRESSOR to snappy, zlib, or zstd. For example:

MONGO_GO_DRIVER_COMPRESSOR=snappy make

Ensure the --networkMessageCompressors flag on mongod or mongos includes zlib if testing zLib compression.


Contribution

Check out the project page for tickets that need completing. See our contribution guidelines for details.


Continuous Integration

Commits to master are run automatically on evergreen.


Thanks and Acknowledgement

@ashleymcnamara - Mongo Gopher Artwork


License

The MongoDB Go Driver is licensed under the Apache License.