Create demo project with EntityFramework Core

Create demo project with EntityFramework Core

Quick link overview[快速访问连接地址]：

• Entity Framework 6
• Migration Overview

Dependencies【依赖说明】

The project code refer office document, you can see : https://learn.microsoft.com/zh-cn/ef/【项目可以参考官方文档，参考地址】

Code First【Code First】

Product

namespace EFCoreConsoleApp.Models
{
    public class Product
    {
        
        public int Id { set; get; }

        public string Name { set; get; } = null!;

        [Column(TypeName="decimal(6,2)")]
        public decimal Price { get; set; }
    }
}
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OrderDetail

namespace EFCoreConsoleApp.Models
{
    public class OrderDetail
    {
        public int Id { get; set; }
        public int Quantity { get; set; }
        public int ProductId { get; set; }
        public int OrderId { get; set; }

        public Order Order { get; set; } = null!;
        public Product Product { get; set; } = null!;
    }
}
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Order

namespace EFCoreConsoleApp.Models
{
    public class Order
    {
        public int Id { get; set; }
        public DateTime OrderPlaced { get; set; }
        public DateTime? OrderFulfilled { get; set; }
        public int CustomerId { get; set; }

        public Customer Customer { get; set; } = null!;
        public ICollection OrderDetails { get; set; } = null!;
    }
}
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Customer

namespace EFCoreConsoleApp.Models
{
    public class Customer
    {
        public int Id { get; set; }
        public string FirstName { get; set; } = null!;
        public string LastName { get; set; } = null!;
        public string? Address { get; set; }
        public string? Phone { get; set; }
        public string? Email { get; set; }
        public int? sex { get; set; }

        public ICollection Orders { get; set; } = null!;
    }
}
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Create DbContext

MyLocalContext

namespace EFCoreConsoleApp.Data
{
    public class MyLocalContext : DbContext
    {

        public DbSet Customers { get; set; } = null!;
        public DbSet Orders { get; set; } = null!;
        public DbSet Products { get; set; } = null!;
        public DbSet OrderDetails { get; set; } = null!;

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            // Get the connection string pattern from : https://learn.microsoft.com/en-us/ef/core/
            optionsBuilder.UseSqlServer("Server=localhost;Database=EFCore;User Id=sa;Password=xxxx123");
        }
    }
}
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Migrations[迁移工具]

Install the tool【安装方式】

The EF Core tools help with design-time development tasks. They are primarily used to manage Migrations and to scaffold a DbContext and entity types by reverse enginerring the schema of a database.

Install the Package manager Console tools by runing the following command in Package Manager Console.【执行安装命令】

Install-Package Microsoft.EntityFrameworkCore.Tools
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Update the tools by running the following command in Package Manager Console.

Update-Package Microsoft.EntityFrameworkCore.Tools
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Verify taht the tools are installed by running the following command:

Get-help about_EntityFrameworkCore
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OR

dotnet ef can be installed as either a global ot local tools. I recommand you to install it as global tools, because most developers do like that.【Mac 命令行执行方式】

Using the following command to install the tools:

dotnet tool install --global dotnet-ef
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Using the following command to update the tools:

dotnet tool update --global dotnet-ef
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Before you can use the tools on a special project, you will need to add the Microsoft.EntityFrameCore.Design package to it:

dotnet add package Microsoft.EntityFrameworkCore.Design
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Verify installation:【验证安装效果】

Add migration【执行迁移工具】

After finished the prepartion, you can generate table by running the following command in order:

dotnet ef migrations add InitialCreate
dotnet ef database update
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You can also refer Migration Commands to implement the same result by running command in your VS IDE.

Add-Migration InitialCreate
Update-Database
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Verify the local database tables:【得到创建的表结果】

Test operations【测试代码】

Here are some demo code to insert or update some data to your database, you can try that and help you release how to do CRUD with EFCore:

using MyLocalContext context = new MyLocalContext();

# region Add Products

// Create a new product
Product veggiSpecial = new Product()
{
    Name = "Veggie Special Pizza",
    Price = 9.9M
};
// Save product
context.Products.Add(veggiSpecial);

Product deluxeMeat = new Product()
{
    Name = "Deluxe Meat Pizza",
    Price = 12.99M
};
context.Products.Add(deluxeMeat);

context.SaveChanges();

#endregion

#region display products
var products = context.Products
    .Where(p => p.Price > 10.0M)
    .OrderBy(p => p.Price);

Console.WriteLine("Use function method way:");
foreach (Product p in products)
{
    Console.WriteLine($"Id:    {p.Id}");
    Console.WriteLine($"Name:  {p.Name}");
    Console.WriteLine($"Price: {p.Price}");
    Console.WriteLine(new string('-', 20));
}
#endregion

#region linqProduct

var productsLinq = from product in context.Products
               where product.Price >= 10.0M
               orderby product.Price descending
               select product;

Console.WriteLine("Use Linq way:");
foreach (Product p in productsLinq)
{
    Console.WriteLine($"Id:    {p.Id}");
    Console.WriteLine($"Name:  {p.Name}");
    Console.WriteLine($"Price: {p.Price}");
    Console.WriteLine(new string('-', 20));
}
#endregion

#region update product
var veggiSpecialUpdate = context.Products
    .Where(p => p.Name == "Veggie Special Pizza")
    .FirstOrDefault();

if (veggiSpecialUpdate is Product)
{
    veggiSpecialUpdate.Price = 11.11M;
}

context.SaveChanges();
#endregion
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Result as sinpshot:【展示效果】

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You can get the first EFCore project by follow the blob step by step. We can have a discussion in private If you meet any problems when create your demo code.
Hope it is helpul for you !【希望有所帮助】