Using Entity Framework 6 with ASP.NET Core 1.0

1. Start with a new C# web app using ASP.NET 5 (Core 1.0)

   • Select the Web API template (preview)

2. Open project.json and remove dnxcore50 from the frameworks section.

   • Leave dnx451 under frameworks.

3. Add Entity Framework under dependencies in the project.json file.

   • This should be the full EF 6.x.

4. Add a DbConfig class that extends DbConfiguration

   public class DbConfig : DbConfiguration
   {
       public DbConfig()
       {
           SetProviderServices("System.Data.SqlClient", SqlProviderServices.Instance);
       }
   }

5. Add a Product entity class.

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

6. Add a SampleDbContext inheriting from DbContext.

   • Place a DbConfigurationType attribute on it with DbConfig.
   • Add a Products property of type DbSet<Product>

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

7. Optionally create a SampleDbInitializer class which inherits from DropCreateDatabaseIfModelChanges<SampleDbContext>.

   • Override the Seed method to see the database with data.

   public class SampleDbInitializer : DropCreateDatabaseIfModelChanges<SampleDbContext>
   {
       protected override void Seed(SampleDbContext context)
       {
           var products = new List<Product>
           {
               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 },
           };
   
           context.Products.AddRange(products);
   
           context.SaveChanges();
       }
   }    

8. Add a static ctor to SampleDbContext to set the context initializer.

   static SampleDbContext()
   {
       Database.SetInitializer(new SampleDbInitializer());
   }    

9. Add a "Data" section to appsettings.json with a connection string

   • Here we specify LocalDb, but SQL Express or full is OK too.

   "Data": {
     "SampleDb": {
       "ConnectionString": "Data Source=(localdb)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\SampleDb.mdf;Integrated Security=True; MultipleActiveResultSets=True"
     }
   }

10. Update the Startup ctor to set the "DataDirectory" for the current AppDomain.

    public Startup(IHostingEnvironment env, IApplicationEnvironment appEnv)
    {
        // Set up configuration sources.
        var builder = new ConfigurationBuilder()
            .AddJsonFile("appsettings.json")
            .AddEnvironmentVariables();
        Configuration = builder.Build();
    
        // Set up data directory
        string appRoot = appEnv.ApplicationBasePath;
        AppDomain.CurrentDomain.SetData("DataDirectory", Path.Combine(appRoot, "App_Data"));
    }

11. Register SampleDbContext with DI system by supplying a new instance of SampleDbContext

    • Add the following code to the ConfigureServices method in Startup

    services.AddScoped(provider =>
    {
        var connectionString = Configuration["Data:SampleDb:ConnectionString"];
        return new SampleDbContext(connectionString);
    });

12. Add a ProductsController that extends Controller

    • Pass SampleDbContext to the ctor
    • Add actions for GET, POST, PUT and DELETE
    • Override Dispose to dispose of the context

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

13. 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:49951/api/products
    POST: http://localhost:49951/api/products
      - Body: {"ProductName":"Ikura","UnitPrice":12}
    GET: http://localhost:49951/api/products/4
    PUT: http://localhost:49951/api/products
      - Body: {"Id":4,"ProductName":"Ikura","UnitPrice":13}
    DELETE: http://localhost:49951/api/products/4