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<MyClass>("COLLECTION_NAME");

Dependency injection

Program.cs

builder.Services .Configure<MongoConfiguration>(builder.Configuration.GetSection("Mongo")) .AddSingleton<IMongoClient>(x => { var mongoConfiguration = x.GetRequiredService<IOptions<MongoConfiguration>>().Value; var settings = MongoClientSettings.FromConnectionString(mongoConfiguration.ConnectionString); settings.LinqProvider = LinqProvider.V3; return new MongoClient(settings); }) .AddSingleton(x => { var client = x.GetRequiredService<IMongoClient>(); var configuration = x.GetRequiredService<IOptions<MongoConfiguration>>().Value; return client.GetDatabase(configuration.DatabaseName); }) .AddSingleton(x => { var database = x.GetRequiredService<IMongoDatabase>(); return database.GetCollection<MyCollection>(GetConfigurationValue("MyCollectionName")); });

MongoConfiguration.cs

public class MongoConfiguration { public string ConnectionString { get; set; } = string.Empty; public string DatabaseName { get; set; } = string.Empty; }

Find

Filter

var builder = Builders<MyClass>.Filter; FilterDefinition<MyClass> filter = builder.Empty; filter &= builder.Exists(x => x.Property1); 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 .Find(filter) .SortByDescending(x => x.Property1) .Skip(100) .Limit(10) .ToListAsync(); var result = (await collection.FindAsync(filter)).ToList();

Handle different types

// get all the documents var bsonDocumentCollection = database.GetCollection<BsonDocument>("MyCollection"); var filter = Builders<BsonDocument>.Filter.Empty; var result = await bsonDocumentCollection.Find(filter).ToListAsync(); // get all the Class1 document var class1Collection = database.GetCollection<Class1>("MyCollection"); await type1Collection.InsertOneAsync(new Class1 { Name = "Name1" }); var filter = Builders<Class1>.Filter.Eq(x => x.Type, nameof(Class1)); var filter = Builders<SimpleClass>.Filter.Exists(x => x.Name); // get all the documents which have a property Name var result = await class1Collection.Find(filter).ToListAsync(); class Class1 { public ObjectId Id { get; set; } public string Name { get; set; } = string.Empty; public string Type { get; set; } = nameof(Class1); }

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.

• Configure logging

Serialize a dictionary with an Enum as key

Error: An error occurred while serializing the Values property of class ...: When using DictionaryRepresentation.Document key values must serialize as strings

class MyClass { public ObjectId Id { get; set; } public Dictionary<MyEnum, int> Values { get; set; } = []; } // serialize the enum as string BsonSerializer.RegisterSerializer(new EnumSerializer<MyEnum>(BsonType.String));