.NET Core and MongoDB generic library

Hello all, you all must have come across lot of code suggestions, answers for your various queries regarding reusable libraries of server side languages and NoSql Databases. But many of those suggestions have code which is specific to that Database, tables, collections. How about writing library which is dynamic and can work with any collection, any field to query upon ?

Yes below is an example of .Net Core and MongoDB reusable dynamic library which is generic and you can use it with any collection. It can be the base for your .net core mongodb generic repository.

Please note that this is not for how to fetch values from config cause you know that better than me. This place is to discuss Coding, Sql, NoSql, Technology, Nuclear Warfare and many more and not to repeat what we have already.

So let's start learning,
Server side language : C#
Framework : .Net Core 2.1
Database : MongoDB
MongoDB Database first,

> use PlayersDB
switched to db PlayersDB
> show tables
tblPlayers
> db.tblPlayers.find();
{ "_id" : 1, "strName" : "Virat", "strPosition" : "One Down", "intAge" : 30, "intMatches" : 100 }
{ "_id" : 2, "strName" : "Rohit", "strPosition" : "Opening", "intAge" : 32, "intMatches" : 120 }
{ "_id" : 3, "strName" : "Virat", "strPosition" : "Last", "intAge" : 25, "intMatches" : 150 }
>

Library class as follows,
Before moving to code, please add required packages for Mongo. 

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Newtonsoft.Json;
using MongoDB.Bson;
using MongoDB.Driver;

using NetCoreMongo.Interfaces;

namespace NetCoreMongo.Model
{
    public class clsMongoDAL : IMongo
    {
        protected static IMongoClient objMdbClient;
        protected static IMongoDatabase objMongoDB;
        protected IMongoCollection<BsonDocument> mongoCollection;
        protected string strMongoDBConnectionstring;
        protected string strMongoDataBase;
        public List<BsonDocument> lstDocuments = null;

        public clsMongoDAL(string strConnectionstring, string strDataBase)
        {
            strMongoDBConnectionstring = strConnectionstring;
            strMongoDataBase = strDataBase;
            objMdbClient = new MongoClient(strConnectionstring);
            objMongoDB = objMdbClient.GetDatabase(strDataBase);
        }

        public IEnumerable<dynamic> GetAll(string strCollectionName)
        {
            try
            {
                mongoCollection = objMongoDB.GetCollection<BsonDocument>(strCollectionName);
                var collections = mongoCollection.Find(new BsonDocument());
                lstDocuments = collections.ToList<BsonDocument>();
            }
            catch (Exception ex) { }
            return (IEnumerable<dynamic>)lstDocuments;
        }
        public IEnumerable<dynamic> GetAllMatching(string strCollectionName, string strField, object strValue)
        {
            var varFilter = Builders<BsonDocument>.Filter.Eq(strField, strValue);
            try
            {
                mongoCollection = objMongoDB.GetCollection<BsonDocument>(strCollectionName);
                var results = mongoCollection.Find(varFilter).ToCursor();
                lstDocuments = results.ToList<BsonDocument>();
            }
            catch (Exception ex) { }
            return (IEnumerable<dynamic>)lstDocuments;
        }
        public async Task<List<BsonDocument>> GetAllMachingAsync(string strCollectionName, string strField, string strValue)
        {
            var varFilter = Builders<BsonDocument>.Filter.Eq(strField, strValue);
            try
            {
                mongoCollection = objMongoDB.GetCollection<BsonDocument>(strCollectionName);
                var results = await mongoCollection.Find(varFilter).ToCursorAsync();
                lstDocuments = results.ToList<BsonDocument>();
            }
            catch (Exception ex) { }
            return lstDocuments;
        }

        public async Task<List<BsonDocument>> GetAllMachingMultiFields(string strCollectionName, FilterDefinition<BsonDocument> filterDefinitions)
        {
            try
            {
                mongoCollection = objMongoDB.GetCollection<BsonDocument>(strCollectionName);
                var results = await mongoCollection.Find(filterDefinitions).ToCursorAsync();
                lstDocuments = results.ToList<BsonDocument>();
            }
            catch (Exception ex) { }
            return lstDocuments;
        }
    }
}

Demo of GetAll and GetAllMatching methods which are generic,

      var connectionString = "mongodb://localhost:27017";
            string strDatabase = "PlayersDB"; 
            string strCollection = "tblPlayers";
            List<clsPlayers> objPlayersList = new List<clsPlayers>();
            clsPlayers objclsPlayers = null;
            try
            {
                clsMongoDAL mongoData = new clsMongoDAL(connectionString, strDatabase);
                //var mongoCollection = mongoData.GetAll(strCollection);
                var mongoCollection = mongoData.GetAllMatching(strCollection, "strName", "Virat");
                
                /// Note : Above line code shows dynamic field name and param can be passed. 
                
                foreach (var strData in mongoCollection)
                {
                    objclsPlayers = new clsPlayers
                    {
                        strName = Convert.ToString(strData.GetValue("strName")),
                        strPosition = Convert.ToString(strData.GetValue("strPosition")),
                        intAge = Convert.ToInt32(strData.GetValue("intAge")),
                        intMatches = Convert.ToInt32(strData.GetValue("intMatches"))
                    };
                    objPlayersList.Add(objclsPlayers);
                }
            }
            catch (Exception ex) { }
            return (objPlayersList != null ? JsonConvert.SerializeObject(objPlayersList) : "");

Now Demo of AND Query i.e. secondary search, please note that the index need to be there on each and every field on which we gonna query.

         var connectionString = "mongodb://localhost:27017";
            string strDatabase = "PlayersDB";
            string strCollection = "tblPlayers";
            List<clsPlayers> objPlayersList = new List<clsPlayers>();
            clsPlayers objclsPlayers = null;
            try
            {
                clsMongoDAL mongoData = new clsMongoDAL(connectionString, strDatabase);

                var varFilter1 = Builders<BsonDocument>.Filter.Eq("strName", "Virat");
                var varFilter2 = Builders<BsonDocument>.Filter.Eq("strPosition", "Last");
                var varFilter3 = Builders<BsonDocument>.Filter.And(varFilter1, varFilter2); 
                Task<List<BsonDocument>> mongoCollection = mongoData.GetAllMachingMultiFields(strCollection, varFilter3);

                //mongoCollection.Wait();   /// Note : optional 

                var varResults = mongoCollection.Result;

                for (int count = 0; count < varResults.Count; count++)
                {
                    objclsPlayers = new clsPlayers
                    {
                        strName = Convert.ToString(varResults[count].GetValue("strName")),
                        strPosition = Convert.ToString(varResults[count].GetValue("strPosition")),
                        intAge = Convert.ToInt32(varResults[count].GetValue("intAge")),
                        intMatches = Convert.ToInt32(varResults[count].GetValue("intMatches"))
                    };
                    objPlayersList.Add(objclsPlayers);
                }
            }
            catch (Exception ex) { }
            return (objPlayersList != null ? JsonConvert.SerializeObject(objPlayersList) : ""); 

Off course we need to handle Null and Not Empty in Result sets but this blog is not about that as you know that better. Thanks for reading.