Performing CRUD Operations With ASP.NET MVC Core And Entity Framework Core

{
  "version": "1.0.0-*",
  "buildOptions": {
    "preserveCompilationContext": true,
    "debugType": "portable",
    "emitEntryPoint": true
  },
  "dependencies": {},
  "frameworks": {
    "netcoreapp1.0": {
      "dependencies": {
        "Microsoft.NETCore.App": {
          "type": "platform",
          "version": "1.0.1"
        },
        "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0",
        "Microsoft.EntityFrameworkCore.SqlServer.Design": "1.0.0",
        "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
        "Microsoft.AspNetCore.Mvc": "1.0.0",
        "Microsoft.AspNetCore.Mvc.Formatters.Xml": "1.0.0",
        "Microsoft.Framework.Configuration.Json": "1.0.0-beta7"
      },
      "imports": [
        "dnxcore50",
        "portable-net452+win81"
      ]
    }
  }
}

CREATE TABLE [dbo].[TestTables] (
    [Id] INT NOT NULL IDENTITY(1,1),
    [Name] VARCHAR(50) NULL,
    [Description] VARCHAR(50) NULL,
    CONSTRAINT [PK_TestTable] PRIMARY KEY CLUSTERED (
        [Id] ASC
    ) WITH (
        PAD_INDEX = OFF,
        STATISTICS_NORECOMPUTE = OFF,
        IGNORE_DUP_KEY = OFF,
        ALLOW_ROW_LOCKS = ON,
        ALLOW_PAGE_LOCKS = ON
    ) ON [PRIMARY]
) ON [PRIMARY];

using Microsoft.EntityFrameworkCore;

namespace WebApplication
{
    public class EntityModelContext : DbContext
    {
        public DbSet<TestTable> TestTables { get; set; }
    }
}

namespace WebApplication
{
    public class TestTable
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
    }
}

{
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=10.124.130.116;Initial Catalog=TestDB;User ID=sa; Password=Passwd@12"
  },
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Debug",
      "System": "Information",
      "Microsoft": "Information"
    }
  }
}

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Framework.Configuration;
using Microsoft.Extensions.DependencyInjection;
using System.IO;
using Microsoft.EntityFrameworkCore.Infrastructure;

namespace WebApplication
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            var builder = new ConfigurationBuilder(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json");

            var configuration = builder.Build();

            services.AddMvc();
            services.AddEntityFramework()
                .AddDbContext<EntityModelContext>(options =>
                    options.UseSqlServer(configuration["ConnectionStrings:DefaultConnection"]));
        }

        public void Configure(IApplicationBuilder app)
        {
            app.UseMvc();

            app.Run(context =>
            {
                return context.Response.WriteAsync("");
            });
        }
    }
}

HomeController.cs

using Microsoft.AspNetCore.Mvc;
using System.Linq;
using System.Collections.Generic;

namespace WebApplication
{
    public class HomeController : Controller
    {
        private EntityModelContext _context = null;

        public HomeController(EntityModelContext context)
        {
            _context = context;
        }

        [Route("home/index")]
        public IActionResult Index()
        {
            List<TestTable> data = _context.TestTables.ToList();
            return View(data);
        }

        [Route("home/edit/{id?}")]
        [HttpGet]
        public IActionResult Edit(int? id)
        {
            TestTable data = new TestTable();
            if (id.HasValue)
            {
                data = _context.TestTables
                    .Where(p => p.Id == id.Value)
                    .FirstOrDefault();
                if (data == null)
                {
                    data = new TestTable();
                }
                return View("Edit", data);
            }
            return View("Edit", data);
        }

        [Route("home/post")]
        [HttpPost]
        public IActionResult Post(TestTable test)
        {
            if (test != null)
            {
                bool isNew = false;
                var data = _context.TestTables
                    .Where(p => p.Id == test.Id)
                    .FirstOrDefault();
                if (data == null)
                {
                    data = new TestTable();
                    isNew = true;
                }
                data.Name = test.Name;
                data.Description = test.Description;
                if (isNew)
                {
                    _context.Add(data);
                }
                _context.SaveChanges();
            }
            return RedirectToAction("Index");
        }

        [Route("home/delete/{id}")]
        [HttpGet]
        public IActionResult Delete(int id)
        {
            TestTable data = _context.Set<TestTable>()
                .FirstOrDefault(c => c.Id == id);
            _context.Entry(data).State = Microsoft.EntityFrameworkCore.EntityState.Deleted;
            _context.SaveChanges();
            return RedirectToAction("Index");
        }
    }
}

Index view (Initial List View)

It is the entry point of the application. Following is the code snippet for index View.

Index.cshtml

@model IEnumerable<WebApplication.TestTable>
@using WebApplication;

<table>
    <thead>
        <tr>
            <th>Id</th>
            <th>Name</th>
            <th>Description</th>
            <th></th>
            <th></th>
        </tr>
    </thead>
    <tbody>
        @foreach (var item in Model)
        {
            <tr>
                <td>@item.Id</td>
                <td>@item.Name</td>
                <td>@item.Description</td>
                <td>@Html.ActionLink("Edit", "Edit", new { Id = item.Id })</td>
                <td>@Html.ActionLink("Delete", "Delete", new { Id = item.Id }, new { onclick = "return confirm('Are you sure you want to delete this record?');" })</td>
            </tr>
        }
    </tbody>
</table>
<br />
@Html.ActionLink("Add Item", "Edit", new { Id = 0 })

When we run this application, we might observe the following error. It is related to Entity Framework and tells us that database provider has not been configured.

“No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext”.

The solution for this error is hidden in the message itself. This message tells us to add a new constructor to our DbContext, which will accept DbContextOption as parameter.

EntityModelContext.cs

public class EntityModelContext : DbContext
{
    public EntityModelContext(DbContextOptions<EntityModelContext> options) : base(options)
    {
    }

    // Other code or methods
}

Now, I am re-running the application. No such error prompts this time and it is running successfully.

Output

Create add /edit/delete view

Now, I am defining the "Add/Edit" View. The following is the code snippet for "edit.cshtml".

Edit.cshtml

@model WebApplication.TestTable
@using WebApplication;

@using (Html.BeginForm("Post", "Home", FormMethod.Post, new { }))
{
    @Html.ValidationSummary(true)

    <fieldset>
        <legend></legend>
        <div class="editor-label">
            ID
        </div>
        <div class="editor-field">
            @Html.TextBoxFor(model => model.Id, new { @readonly = "readonly" })
        </div>
        <div class="editor-label">
            Name
        </div>
        <div class="editor-field">
            @Html.TextBoxFor(model => model.Name)
            @Html.ValidationMessageFor(model => model.Name)
        </div>
        <div class="editor-label">
            Description
        </div>
        <div class="editor-field">
            @Html.TextBoxFor(model => model.Description)
            @Html.ValidationMessageFor(model => model.Description)
        </div>

        <p>
            <input type="submit" value="Update" id="btnsave" />
        </p>
    </fieldset>
}

<div>
    @Html.ActionLink("Close", "Index")
</div>

Output

At the time of deleting items, the system will ask for conformation. And if the user clicks on “Ok” button, system will delete the record from database.

Delete conformation

Conclusion

This article gave us the insights of CRUD operations in ASP.NET Core MVC, using Entity Framework Core. In the example, I have used simple form post method to perform the CRUD operations.