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Working with MongoDB in .Net Core (Part 1) - Mongo Connection Manager


Connecting to Mongo Database C#

Mongo DB is a NoSQL document-oriented database which stores data in a JSON-like format. Mongo DB stores the data in a binary-encoded format called BSON. Every application connecting to Mongo DB will have a Mongo connection manager to create Mongo Clients and connect to database and collection to perform CRUD operations. Here is a sample of how a Mongo Connection manager would look like,

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using MongoDB.Bson;
using MongoDB.Bson.Serialization.Conventions;
using MongoDB.Driver;

public class MongoConnectionManager : IMongoConnectionManager
{
    public IMongoClient client { get; set;}
    private readonly MongoDBConfigSettings _mongoDBSettings;
    //Setup Mongo Client in the connection Manager constructor when the instance is created, so that it can be dependency injected into other classes
    public MongoConnectionManager(IOptions<MongoDBConfigSettings> mongoDBSettings)
    {
        mongoDBSettings = _mongoDBSettings.Value;
        client = GetMongoClient();
    }
}

GetMongoClient - 

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private IMongoClient GetMongoClient()
{
    try
    {
        var settings = new MongoClientSettings
        {
            ConnectionMode = ConnectionMode.Automatic,
            UseSSL = MongoDBSettings.UseSSL,
            //Get all the settings from Config (Can be in Spring Cloud or some project config files)
            MinConnectionPoolSize = MongoDBSettings.MinConnectionPoolSize,
            MaxConnectionIdleTime = new TimeSpan(0,0,0,0,MongoDBSettings.MaxConnectionIdleTime),
            ServerSelectionTimeout = new TimeSpan(0,0,0,0,MongoDBSettings.ServerSelectionTimeout),
            ConnectTimeout = new TimeSpan(0,0,0,0,MongoDBSettings.ConnectTimeout),
            SocketTimeout = new TimeSpan(0,0,0,0,MongoDBSettings.SocketTimeout)
        };
        var pack = new ConventionPack
        {
            new IgnoreExtraElementsConvention(true)
        };
        ConventionRegistry.Register("IgnoreConvention", pack, t => true);
        
        //Set up Read/Write Preferences
        var wc = new WriteConcern(WriteConcern.WMajority.W, new TimeSpan(0,0,0,0,MongoDBSettings.WriteTimeout));
        settings.WriteConcern = wc;
        settings.ReadPreference = ReadPreference.PrimaryPreferred;
        //Configuring the Mongo Server to connect
        var serverslist = MongoDBSettings.Servers;
        var servers = serverslist.Split(',');
        var mdbServerList = servers.Select(server=>server.Split(',').Select(addressportArray=>
                                       new MongoServerAddress(addressportArray[0], Convert.ToInt32(addressportArray[1])))).ToList();
        settings.Servers = mdbServerList;
        settings.Credential = MongoCredential.CreatePlainCredential("$external", MongoDBSettings.User, MongoDBSettings.Password);
        settings.RetryWrites = true;
        var connectionString = MongoDBSettings.MongoConnectionStringOverride;
        return !string.IsNullOrWhiteSpace(connectionString) ? new MongoClient(connectionString) : new MongoClient(settings);
    }
    catch (System.Exception ex)
    {
        throw ex;
    }
}

GetDatabase - 

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private IMongoDatabase GetDatabase()
{
    if (client == null) { throw ex; };
    return client.GetDatabase(databaseName);
}

GetCollection -

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public IMongoCollection<T> GetCollection<T>(string collectionName)
{
    IMongoDatabase db = GetDatabase();
    IMongoCollection<T> collection = null;

    if(GetMongoDBConnectionStatus())  
    { 
        collection = db.GetCollection<T>(collectionName) 
    };
    else 
    { 
        RetryMongoHasCollection() 
    };

    return collection;
}

//Ping the database to check db connection
public bool GetMongoDBConnectionStatus()
{
    IMongoDatabase db = null;
    try
    {
        db = GetDatabase();
        var pingCommand = new BsonDocument("ping", 1;);
        var status = db.RunCommand<MongoPingStatus>(pingCommand);
        return status.ok == 1;
    }
}

//Attempt to retry connection
public bool RetryMongoHasCollection()
{
    var maxRetryCount = MongoDBSettings.maxRetryCount;
    var retryInterval = MongoDBSettings.retryInterval;
    var connected = false; int i=1;
    for (int i = 1; i < maxRetryCount; i++)
    {
        System.Threading.Thread.Sleep(retryInterval);
        if(GetMongoDBConnectionStatus())
        {
            connected = true;
            break;
        }
    }

    if (connected) { Log("Connected after x attempts")}
    else { throw ex)"Failed to Reconnect"};

    return true;
}



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