Mongodb and csharp

Links

• Using LINQ to Query MongoDB in a .NET Core Application
• Create a RESTful API with .NET Core and MongoDB
• Joining Collections in MongoDB with .NET Core and an Aggregation Pipeline
• C# and MongoDB

Access to a collection

var mongoClient = new MongoClient("MONGODB_CONNECTION_STRING"); var database = mongoClient.GetDatabase("DB_NAME"); var collection = database.GetCollection<Collection>("COLLECTION_NAME");

Filter

var builder = Builders<MyClass>.Filter; FilterDefinition<MyClass> filter = filterDefinition.Empty; filter &= builder.Eq(x => x.Property1, "id"); filter &= builder.In(x => x.Property1, new[] { "id1", "id2" }); // filter by Property1 equals to one of the ids var result = (await collection.FindAsync(filter)).ToList();

Pipeline

var stages = new BsonDocument[] { MatchStage(getTimeSeriesQuery), ProjectionStage(), SortStage() }; var pipeline = PipelineDefinition<InputClass, OutputClass>.Create(stages); var results = (await myCollection.AggregateAsync(pipeline)).List(); BsonDocument MatchStage(GetTimeSeriesQuery getTimeSeriesQuery) { var match = new BsonDocument("property1", "value1"); if (!string.IsNullOrEmpty(variable2)) { match.AddRange( new BsonDocument("property2", variable2) ); } return new BsonDocument("$match", match); } BsonDocument ProjectionStage() => new BsonDocument( "$project", new BsonDocument { { "_id", 0 }, { "property1", 1 }, { "property2", 1 } } ); BsonDocument SortStage() => new BsonDocument("$sort", new BsonDocument("timestamp", 1));

Log

var mongoUrl = new MongoUrl("MONGODB_CONNECTION_STRING"); var mongoClientSettings = MongoClientSettings.FromUrl(mongoUrl); mongoClientSettings.ClusterConfigurator = cb => { cb.Subscribe<CommandStartedEvent>(e => { logger.LogTrace($"{e.CommandName} - {e.Command.ToJson()}"); }); }; this.mongoClient = new MongoClient(mongoClientSettings);

Configure the Log so it will be displayed in Visual Studio Output Debug window.

Errors

Requested value '_id' was not found

await collection.Find(_ => true).ToListAsync(); // query with an id (the objects you want to retrieve must have a property ObjectId Id) await collection.Find(x => x.Id == new ObjectId("...")).ToListAsync();