MongoDB Go Driver

The MongoDB supported driver for Go.

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• Requirements
• Installation
• Usage
• Bugs / Feature Reporting
• Testing / Development
• Continuous Integration
• License

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Requirements

• Go 1.10 or higher. We aim to support the latest supported versions of go.
• MongoDB 2.6 and higher.

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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"

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Usage

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

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

client, err := mongo.NewClient(options.Client().ApplyURI("mongodb://localhost:27017"))

And connect it to your running MongoDB server:

ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
err = client.Connect(ctx)

To do this in a single step, you can use the Connect function:

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)
    }
}()

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.M{"name": "pi", "value": 3.14159})
id := res.InsertedID

To use bson.M, 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.M
   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.M{"name": "pi"}
ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
err = collection.FindOne(ctx, filter).Decode(&result)
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.

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Bugs / Feature Reporting

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

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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:27018/?replicaSet=rs1" make

Testing Auth and SSL

To test authentication and SSL, first set up a MongoDB cluster with auth and SSL configured. Testing authentication requires a user with the root role on the admin database. The Go Driver repository comes with example certificates in the data/certificates directory. These certs can be used for testing. Here is an example command that would run a mongod with SSL correctly configured for tests:

mongod \
--auth \
--sslMode requireSSL \
--sslPEMKeyFile $(pwd)/data/certificates/server.pem \
--sslCAFile $(pwd)/data/certificates/ca.pem \
--sslWeakCertificateValidation

To run the tests with make, set MONGO_GO_DRIVER_CA_FILE to the location of the CA file used by the database, set MONGODB_URI to the connection string of the server, set AUTH=auth, and set SSL=ssl. For example:

AUTH=auth SSL=ssl MONGO_GO_DRIVER_CA_FILE=$(pwd)/data/certificates/ca.pem  MONGODB_URI="mongodb://user:password@localhost:27017/?authSource=admin" make

Notes:

• The --sslWeakCertificateValidation 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.

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Feedback

The MongoDB Go Driver is not feature complete, so any help is appreciated. Check out the project page for tickets that need completing. See our contribution guidelines for details.

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Continuous Integration

Commits to master are run automatically on evergreen.

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Thanks and Acknowledgement

@ashleymcnamara - Mongo Gopher Artwork

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License

The MongoDB Go Driver is licensed under the Apache License.