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MongoDB is a cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with schema.

CAP supports MongoDB since version 2.3 .

MongoDB supports ACID transactions since version 4.0, so CAP only supports MongoDB above 4.0, and MongoDB needs to be deployed as a cluster, because MongoDB's ACID transaction requires a cluster to be used.

For a quick development of the MongoDB 4.0+ cluster for the development environment, you can refer to this article.


To use MongoDB storage, you need to install the following package from NuGet:

PM> Install-Package DotNetCore.CAP.MongoDB

Next, add configuration items to the ConfigureServices method of Startup.cs.

public void ConfigureServices(IServiceCollection services)
    // ...

    services.AddCap(x =>
        // x.UseXXX ...

MongoDB Options

DatabaseName Database name string cap
DatabaseConnection Database connection string string mongodb://localhost:27017
ReceivedCollection Database received message collection name string cap.received
PublishedCollection Database published message collection name string cap.published

Publish with transaction

The following example shows how to leverage CAP and MongoDB for local transaction integration.

//NOTE: Before your test, your need to create database and collection at first.
//      Mongo can't create databases and collections in transactions automatic, 
//      so you need to create them separately, simulating a record insert 
//      will automatically create.

// var mycollection = _client.GetDatabase("test")
//          .GetCollection<BsonDocument>("test.collection");
// mycollection.InsertOne(new BsonDocument { { "test", "test" } });

using (var session = _client.StartTransaction(_capBus, autoCommit: false))
    var collection = _client.GetDatabase("test")

    collection.InsertOne(session, new BsonDocument { { "hello", "world" } });

    _capBus.Publish("sample.rabbitmq.mongodb", DateTime.Now);