Using Entity Framework 6 with ASP.NET Core 2.0

1. Create a solution with Visual Studio 2017 and add a new .NET Class Library project.

   • Select Windows Classic Desktop, Class Library

   

   • Specify a .NET Framework version (for ex, 4.7)
   • Add the EF6 NuGet package.

   

2. Add a Product entity class to a Models folder.

   public class Product
   {
       public int Id { get; set; }
       public string ProductName { get; set; }
       public decimal UnitPrice { get; set; }
   }

3. Add a SampleDbContext to a Contexts folder and inherit from DbContext.

   • Add a Products property of type DbSet<Product>

     public class SampleDbContext : DbContext
     {
         public SampleDbContext(string connectionName) :
             base(connectionName) { }
     
         public DbSet<Product> Products { get; set; }
     }

4. Add a SampleDbContextFactory class to the Contexts folder.

   • Implement IDbContextFactory

   • Return a new SampleDbContext in the Create method

   • Specify a connection string for the SampleDb database

     class SampleDbContextFactory : IDbContextFactory<SampleDbContext>
     {
         public SampleDbContext Create()
         {
             return new SampleDbContext(@"Server=(localdb)\mssqllocaldb;Database=SampleDb;Trusted_Connection=True;MultipleActiveResultSets=true");
         }
     }

5. In Package Manager Console select the class library project

   • Run the following command: Enable-Migrations

   • Add code to the Seed method in the Configuration class in the Migrations folder

     context.Products.AddOrUpdate(
         new Product { Id = 1, ProductName = "Chai", UnitPrice = 10 },
         new Product { Id = 2, ProductName = "Chang", UnitPrice = 11 },
         new Product { Id = 3, ProductName = "Aniseed Syrup", UnitPrice = 12 }
     );

   • Run the Add-Migration Initial command

   • Run the Update-Database command

   • Add a data connection to the Server Explorer

   • Verify that the SampleDb database exists and that the Products table contains data

6. Add a new Web project to the solution.

   • Select .NET Core, ASP.NET Core Web Application

   

   • Select Web API targeting the full .NET Framework

   

   • Set the web project as the startup project for the solution
   • Add the EF6 Nuget package to the web project
   • Add a project reference to the Data class library project

   

   • Build the solution.

7. Open appsettings.json in the Web project and add the connection string

   "ConnectionStrings": {
       "SampleDb": "Server=(localdb)\\mssqllocaldb;Database=SampleDb;Trusted_Connection=True;MultipleActiveResultSets=true"
   }

8. In the Web project register the context for DI in Startup.cs.

   • Add following code after services.AddMvc() in the ConfigureServices method

     services.AddScoped(provider =>
     {
         var connectionString = Configuration.GetConnectionString("SampleDb");
         return new SampleDbContext(connectionString);
     });

9. Add a ProductsController that extends Controller

   

   • Pass SampleDbContext to the ctor

   • Add actions for GET, POST, PUT and DELETE

     [Route("api/[controller]")]
     public class ProductsController : Controller
     {
         private readonly SampleDbContext _dbContext;
     
         public ProductsController(SampleDbContext dbContext)
         {
             _dbContext = dbContext;
         }
     
         // GET: api/products
         [HttpGet]
         public async Task<ActionResult> Get()
         {
             var products = await _dbContext.Products
                 .OrderBy(e => e.ProductName)
                 .ToListAsync();
             return Ok(products);
         }
     
         // GET api/products/5
         [HttpGet("{id}")]
         public async Task<ActionResult> Get(int id)
         {
             var product = await _dbContext.Products
                 .SingleOrDefaultAsync(e => e.Id == id);
             if (product == null)
                 return NotFound();
             return Ok(product);
         }
     
         // POST api/products
         [HttpPost]
         public async Task<ActionResult> Post([FromBody]Product product)
         {
             _dbContext.Entry(product).State = EntityState.Added;
     
             await _dbContext.SaveChangesAsync();
             return CreatedAtAction("Get", new { id = product.Id }, product);
         }
     
         // PUT api/products
         [HttpPut]
         public async Task<ActionResult> Put([FromBody]Product product)
         {
             _dbContext.Entry(product).State = EntityState.Modified;
     
             await _dbContext.SaveChangesAsync();
             return Ok(product);
         }
     
         // DELETE api/products/5
         [HttpDelete("{id}")]
         public async Task<ActionResult> Delete(int id)
         {
             var product = await _dbContext.Products
                 .SingleOrDefaultAsync(e => e.Id == id);
             if (product == null) return Ok();
     
             _dbContext.Entry(product).State = EntityState.Deleted;
             await _dbContext.SaveChangesAsync();
             return Ok();
         }
     }

10. Test the controller by running the app and submitting some requests.

    • Use Postman or Fiddler

    • Set Content-Type header to application/json for POST and PUT.

    • The database should be created automatically

      GET: http://localhost:50781/api/products
      POST: http://localhost:50781/api/products
        - Body: {"productName":"Ikura","unitPrice":12}
      GET: http://localhost:50781/api/products/4
      PUT: http://localhost:50781/api/products/4
        - Body: {"id":4,"productName":"Ikura","unitPrice":13}
      DELETE: http://localhost:50781/api/products/4