Example of mongodb repository in C#

Repository.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
using MongoDB.Bson;
using MongoDB.Driver;
using MongoDB.Driver.Builders;
using MongoDB.Driver.Linq;

namespace PRJ.Data
{
    public class Repository<T> where T : IEntity<ObjectId>
    {
        DataContext _context;
        MongoCollection<T> _collection;

        public MongoCollection<T> Collection { get { return _collection; } }

        public Repository( DataContext context )
        {
		_context = context;
		_collection = _context.GetDatabase().GetCollection<T>( typeof( T ).Name.ToLower() );
        }

        private IQueryable<T> CreateSet()
        {
		return _collection.AsQueryable<T>();
        }

        public T Insert( T instance )
        {         
		try
		{
			instance.Id = ObjectId.GenerateNewId();
			_collection.Insert<T>( instance );
			
			return instance;
		}
		catch( Exception ex )
		{
			//todo: handle exception
			throw ex;
		}
        }

        public void Update( T instance )
        {
		try
		{
			var query = Query<T>.EQ( o => o.Id, instance.Id );
			var update = Update<T>.Replace( instance );
			_collection.Update( query, update );
		}
		catch( Exception ex )
		{
			//todo: handle exception
			throw ex;
		}
        }

        public void Delete( ObjectId id, bool logical = true  )
        {
		try
		{
			if( logical )
			{
			    _collection.Update(
				 Query<T>.EQ<ObjectId>( p => p.Id, id ),
				 Update<T>.Set<bool>( p => p.Deleted, true ) );
			}
			else
			{
			    _collection.Remove( Query<T>.EQ<ObjectId>( p => p.Id, id ) );
			}
		}
		catch( Exception ex )
		{
			//todo: handle exception
			throw ex;
		}
        }

        public T GetById( ObjectId id )
        {
		return this.Single( o => o.Id == id );
        }

        public T Single( Expression<Func<T, bool>> predicate = null )
        {
		var set = CreateSet();
		var query = ( predicate == null ? set : set.Where( predicate ) );
		
		return query.SingleOrDefault();
        }

        public IReadOnlyList<T> List( Expression<Func<T, bool>> condition = null, Func<T, string> order = null )
        {
		var set = CreateSet();
		if( condition != null )
		{
			set = set.Where( condition );
		}

		if( order != null )
		{
			return set.OrderBy( order ).ToList();
		}
		
		return set.ToList();
        }

        public int Count( Expression<Func<T, bool>> predicate = null )
        {
		var set = CreateSet();
		
		return ( predicate == null ? set.Count() : set.Count( predicate ) );
        }

        public bool Exists( Expression<Func<T, bool>> predicate )
        {
		var set = CreateSet();
		return set.Any( predicate );
        }
    }
    
    public class DataContext
    {
        string _mongoServerUrl;
        string _mongoDbName;
        MongoClient _client;

        public DataContext( string dburl, string dbname )
        {
		_mongoServerUrl = dburl;
		_mongoDbName = dbname;		
		_client = new MongoClient( _mongoServerUrl );
	}

        public MongoDatabase GetDatabase() { return _client.GetServer().GetDatabase( _mongoDbName ); }

        public void DropDatabase( string dbName )
        {
		var server = _client.GetServer();
		server.DropDatabase( dbName );
        }

        public void DropCollection<T>() where T : IEntity<ObjectId>
        {
            var database = GetDatabase();
            var collectionName = typeof( T ).Name.ToLower();

            if( database.CollectionExists( collectionName ) )
            {
                database.DropCollection( collectionName );
            }
        }
    }
    
    public interface IEntity<T>
    {
	T Id { get; set; }
	bool Deleted { get; set; }
    }
}

What would you do with aggregations? I believe you only support composition, meaning objects contain the whole objects inside them, instead of keeping a reference inside. Is that right?

Hi bprhw, 'CreateNotdeletedSet()' was a refuse of an old code. I just updated it.

Sorry for delay of the answer :)

Hi Mahadi-K, you are right this example provides only composition support. I'm not sure that could be useful to have a reference to object when i'm working with non relational approach.

Hi antdimot, these code snippets are exactly what I was looking for.... Do you have a sample project where this pattern is implemented? Maybe in a WebApi?

Hi @ Skrappy , I have just released a project that use it.

gstore

I don't understand why do you need "Deleted" property in IEntity.

I don't understand why do you need "Deleted" property in IEntity.

Its for logical delete only.

Hi @antdimot. I just wonder, in your DataContext class you have a private var called _mongoDbName and you are setting it within the constructor.
Then for the "DropDatabase" method you are getting dbname as a parameter which may be out of db context. What is the purpose? Thanks.

You are right. The DataContext should not able to drop the database.