ASP.NET Core Web API + MongoDB | CRUD APIs

In this post we will learn how to create CRUD API in ASP.NET Core Web API project with MongoDB as the database.

You can create a free Mongo DB cluster for learning purposes here:

https://www.mongodb.com/cloud/atlas

Also, please install MongoDB Compass which is a graphical user interface using which we can connect to our MongoDB  cluster, create and manage the database object.

https://www.mongodb.com/try/download/compass

* Create a database in MongoDB Compass:

* Add Department collection and some sample data:

* Similarly, add Employee collection and data.

* Lets create the dot net core web API project.

-> Lets open up visual studio first.

-> Click on create a new project.

-> Choose ASP dot net core Web API .

->Choose appropriate folder.

->We might not need HTTPS for now.

Now lets take a look at some of the important files in the project.

-> All the dependencies and packages needed for our app can be found in the dependencies folder.

-> launchSettings.json file contains the details of how the project should be started.

-> Controllers folders contains controllers in which we write our API methods.

-> We generally keep the configuration details such as database details in appSettings.json.

-> The program.cs contains the Main() program which is the entry point of our app.

-> Also it creates web host which basically helps the app to listen to http requests.

-> The startup class configures all the services needed for our app. Services are basically reusable components that can be used across our app using dependency

Injection. It also contains the configure method which creates our app’s request processing pipeline.

We need to make a couple of changes in startup class.

One is to enable the CORS.

By default, all web API projects come with a security which blocks requests coming from different domains. We are basically writing instructions to disable that security and allow the requests to be served.

We are also making one more change to the serializer class to keep the json serializer as our default.

We might need to install a nuget package to do this.

Startup.cs Complete code:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Newtonsoft.Json.Serialization;
using Microsoft.Extensions.FileProviders;
using System.IO;

namespace WebApplication1
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            //Enable CORS
            services.AddCors(c =>
            {
                c.AddPolicy("AllowOrigin", options => options.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader());
            });


            //JSON Serializer
            services.AddControllersWithViews().AddNewtonsoftJson(options =>
            options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore)
                .AddNewtonsoftJson(options => options.SerializerSettings.ContractResolver
                = new DefaultContractResolver());

            services.AddControllers();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            //Enable CORS
            app.UseCors(options => options.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader());

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });

            app.UseStaticFiles(new StaticFileOptions
            {
                FileProvider = new PhysicalFileProvider(
                   Path.Combine(Directory.GetCurrentDirectory(), "Photos")),
                RequestPath = "/Photos"
            });
        }
    }
}

The below code in startup.cs is basically to use the folder 'Photos' for image uploads.

 app.UseStaticFiles(new StaticFileOptions
            {
                FileProvider = new PhysicalFileProvider(
                   Path.Combine(Directory.GetCurrentDirectory(), "Photos")),
                RequestPath = "/Photos"
            });

Please also add a folder with name 'Photos'.

To work with MongoDB server, please also add below nuget package (Mongodb.driver).

Next, add the models.





Department.cs:

using MongoDB.Bson;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace WebApplication1.Models
{
    public class Department
    {
        public ObjectId Id { get; set; }
        public int DepartmentId { get; set; }
        public string DepartmentName { get; set; }
    }
}

Employee.cs:

using MongoDB.Bson;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace WebApplication1.Models
{
    public class Employee
    {
        public ObjectId Id { get; set; }

        public int EmployeeId { get; set; }

        public string EmployeeName { get; set; }

        public string Department { get; set; }

        public string DateOfJoining { get; set; }

        public string PhotoFileName { get; set; }
    }
}

*Add Connection string for MongoDB cluster in appsettings json file:

* Finally, add the Controller files with CRUD methods.

DepartmentController.cs:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using MongoDB.Driver;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class DepartmentController : ControllerBase
    {
        private readonly IConfiguration _configuration;
        public DepartmentController(IConfiguration configuration)
        {
            _configuration = configuration;
        }

        [HttpGet]
        public JsonResult Get()
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            var dbList = dbClient.GetDatabase("testdb").GetCollection<Department>("Department").AsQueryable();

            return new JsonResult(dbList);
        }

        [HttpPost]
        public JsonResult Post(Department dep)
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            int LastDepartmentId = dbClient.GetDatabase("testdb").GetCollection<Department>("Department").AsQueryable().Count();
            dep.DepartmentId = LastDepartmentId + 1;

            dbClient.GetDatabase("testdb").GetCollection<Department>("Department").InsertOne(dep);

            return new JsonResult("Added Successfully");
        }

        [HttpPut]
        public JsonResult Put(Department dep)
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            var filter = Builders<Department>.Filter.Eq("DepartmentId",dep.DepartmentId);

            var update = Builders<Department>.Update.Set("DepartmentName", dep.DepartmentName);



            dbClient.GetDatabase("testdb").GetCollection<Department>("Department").UpdateOne(filter,update);

            return new JsonResult("Updated Successfully");
        }


        [HttpDelete("{id}")]
        public JsonResult Delete(int id)
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            var filter = Builders<Department>.Filter.Eq("DepartmentId", id);


            dbClient.GetDatabase("testdb").GetCollection<Department>("Department").DeleteOne(filter);

            return new JsonResult("Deleted Successfully");
        }



    }
}

EmployeeController.cs:

using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using MongoDB.Driver;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class EmployeeController : ControllerBase
    {

        private readonly IConfiguration _configuration;
        private readonly IWebHostEnvironment _env;
        public EmployeeController(IConfiguration configuration,IWebHostEnvironment env)
        {
            _configuration = configuration;
            _env = env;
        }

        [HttpGet]
        public JsonResult Get()
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            var dbList = dbClient.GetDatabase("testdb").GetCollection<Employee>("Employee").AsQueryable();

            return new JsonResult(dbList);
        }

        [HttpPost]
        public JsonResult Post(Employee emp)
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            int LastEmployeeId = dbClient.GetDatabase("testdb").GetCollection<Department>("Employee").AsQueryable().Count();
            emp.EmployeeId = LastEmployeeId + 1;

            dbClient.GetDatabase("testdb").GetCollection<Employee>("Employee").InsertOne(emp);

            return new JsonResult("Added Successfully");
        }

        [HttpPut]
        public JsonResult Put(Employee emp)
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            var filter = Builders<Employee>.Filter.Eq("EmployeeId", emp.EmployeeId);

            var update = Builders<Employee>.Update.Set("EmployeeName", emp.EmployeeName)
                                                    .Set("Department", emp.Department)
                                                    .Set("DateOfJoining", emp.DateOfJoining)
                                                    .Set("PhotoFileName", emp.PhotoFileName);

            dbClient.GetDatabase("testdb").GetCollection<Employee>("Employee").UpdateOne(filter, update);

            return new JsonResult("Updated Successfully");
        }


        [HttpDelete("{id}")]
        public JsonResult Delete(int id)
        {
            MongoClient dbClient = new MongoClient(_configuration.GetConnectionString("EmployeeAppCon"));

            var filter = Builders<Employee>.Filter.Eq("EmployeeId", id);


            dbClient.GetDatabase("testdb").GetCollection<Employee>("Employee").DeleteOne(filter);

            return new JsonResult("Deleted Successfully");
        }


        [Route("SaveFile")]
        [HttpPost]
        public JsonResult SaveFile()
        {
            try
            {
                var httpRequest = Request.Form;
                var postedFile = httpRequest.Files[0];
                string filename = postedFile.FileName;
                var physicalPath = _env.ContentRootPath + "/Photos/" + filename;

                using(var stream=new FileStream(physicalPath, FileMode.Create))
                {
                    postedFile.CopyTo(stream);
                }

                return new JsonResult(filename);
            }
            catch (Exception)
            {

                return new JsonResult("anonymous.png");
            }
        }



    }
}

Github link: https://github.com/ArtOfEngineer/dot-NET-Core-API-Mongo-DB-Vue-JS/tree/main/api/WebApplication1