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@GaProgMan GaProgMan/Circle.cs Secret
Last active Nov 19, 2016

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Code snippets for the blog article at 2016/11/09/entity-framework-core-probing-your-databases
dotnet restore
dotnet ef migrations add InitialMigration
dotnet ef database update
// Circle implements IShape
public interface Circle : IShape
{
public void Draw()
{
// code to draw the shape here
}
public void Rotate(int degrees)
{
// rotating circles is hard
return;
}
public void Scale(int scaleMultiplier)
{
// code to scale here
}
}
// the namespace with our data models - more on those in a moment
using CustomModels;
// the Entity Framework namespace
using Microsoft.EntityFrameworkCore;
namespace DatabaseContexts
{
public class DatabaseContext : DbContext
{
public DatabaseContext(DbContextOptions<DatabaseContext> options) : base(options) { }
public DatabaseContext() { }
// DbSet of our Product class
public DbSet<Product> Products { get; set; }
}
}
var user = context.Users.GetOrCreate(userId);
using Microsoft.EntityFrameworkCore;
SELECT TOP 1 * FROM PRODUCTS WHERE ProductId = key
using System;
using System.Collections.Generic;
using Microsoft.EntityFrameworkCore.Migrations;
namespace MyApp.Migrations
{
public partial class InitialMigration : Migration
{
protected override void Up(MigrationBuilder migrationBuilder)
{
}
protected override void Down(MigrationBuilder migrationBuilder)
{
}
}
}
using CustomModels;
// for IEnumerable<T>
using System.Collections.Generic;
namespace MyRepositories
{
public interface IProductRepository
{
void AddOrUpdate(Product item);
IEnumerable<Product> GetAll();
Product Find(int key);
void Remove(int key);
void Update(Product item);
}
}
public interface IShape
{
void Draw();
void Rotate(int degrees);
void Scale(int scaleMultiplier);
}
using CustomModels;
using MyRepositories;
using System;
using Microsoft.AspNetCore.Mvc;
namespace MyApp.Controllers
{
[RouteAttribute("/")]
public class MyController : Controller
{
private IRepository _repository { get; set; }
public MyController(IRepository repository)
{
_repository = repository;
}
}
}
[HttpPost]
public string AddNewProduct()
{
_repository.AddOrUpdate(new Product{
ProductName = "Classic Widget",
ProductDescription = "A Classic Widget - does not contain any special add ons",
Created = DateTime.Now,
Modified = DateTime.Now
});
return "Added new product";
}
namespace CustomModels
{
public class Product
{
// our primary key
public int ProductId { get; set; }
public string ProductName { get; set; }
public string ProductDescription { get; set; }
// audit data
public DateTime Created { get; set; }
public DateTime Modified { get; set; }
}
}
using DatabaseContexts;
using CustomModels;
using Microsoft.EntityFrameworkCore;
// for IEnumerable<T>
using System.Collections.Generic;
// for LINQ things
using System.Linq;
namespace MyRepositories
{
public class ProductRespository : IProductRepository
{
// Dependency injection will happen here. The DatabaseContext
// class will be injected into the constructor from the
// IServicesCollection - more on that later
private DatabaseContext _context;
public ProductRespository(DatabaseContext context)
{
_context = context;
}
public void AddOrUpdate(Product item)
{
var databaseEntity = _context.Find(Product.ProductId);
// If we can't find an instance of the product
// in the database, then we need to add it to
// the DbSet.
// Assumption: a Product with an empty name is a new instance
if (_string.IsNullOrEmpty(databaseEntity.ProductName))
{
_context.Products.Add(item);
}
// Otherwise we want to update it
else
{
Update(item);
}
_context.SaveChanges();
}
public Product Find(int key)
{
return _context.Products
.Where(prod => prod.ProductId == key)
.SingleOrDefault();
}
public IEnumerable<Product> GetAll()
{
return _context.Products.AsNoTracking();
}
public void Remove(int key)
{
var itemToRemove = _context.Products
.SingleOrDefault(prod => prod.ProductId == key);
if (itemToRemove != null)
{
_context.Products.Remove(itemToRemove);
_context.SaveChanges();
}
}
public void Update(Product item)
{
var itemToUpdate = _context.Product
.SingleOrDefault(prod => prod.ProductId == item.ProductId);
if (itemToUpdate != null)
{
// TODO: add code to update entity fields here
_context.SaveChanges();
}
}
}
}
"dependencies": {
"Microsoft.EntityFrameworkCore": "1.0.0",
"Microsoft.EntityFrameworkCore.Sqlite": "1.0.0",
"Microsoft.EntityFrameworkCore.Sqlite.Design": {
"version": "1.0.0",
"type": "build"
},
"Microsoft.EntityFrameworkCore.Tools": {
"version": "1.0.0-preview2-final",
"type": "build"
}
},
"tools": {
"Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final",
}
"ConnectionStrings": {
"DefaultConnection": "Data Source=myDatabase.db"
}
// need to reference Entity Framework
using Microsoft.EntityFrameworkCore;
// also need to reference our contexts namespace
using DatabaseContexts;
namespace MyApp
{
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
// Add a reference to our DatabaseContext class as a DbContext.
// Use our DefaultConnection string from the appsettings.json
services.AddDbContext<DatabaseContext>(options =>
options.UseSqlite(Configuration.GetConnectionString("DefaultConnection")));
}
}
}
// we need to reference our Respositories
using MyRepositories;
namespace MyApp
{
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
// DI our interfaces into out controllers
services.AddTransient<IProductRepository, ProductRespository>();
}
}
}
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