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+# 实现其它微服务
+
+## 创建实体
+
+```csharp
+HelloWorld.ProductService.Entities.Products
+
+Product & CatalogBrand
+
+```
+
+## EfCore 使用 PostgreSQL 数据库
+
+```shell
+dotnet add package Npgsql.EntityFrameworkCore.PostgreSQL
+```
+
+## 创建 DbContext 上下文
+
+```csharp
+namespace HelloWorld.ProductService.EntityFrameworks
+{
+    public class ProductServiceDbContext(DbContextOptions<ProductServiceDbContext> options) : DbContext(options)
+    {
+        protected override void OnModelCreating(ModelBuilder builder)
+        {
+            base.OnModelCreating(builder);
+
+            builder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
+        }
+    }
+}
+```
+
+## 创建实体配置类
+
+```csharp
+namespace HelloWorld.ProductService.EntityFrameworks.EntityConfigurations.Products
+{
+    public class ProductEntityTypeConfiguration : IEntityTypeConfiguration<Product>
+    {
+        public void Configure(EntityTypeBuilder<Product> builder)
+        {
+            builder.ToTable("Products");
+
+            builder.Property(x => x.Name).HasMaxLength(32);
+
+            builder.HasOne(x => x.Brand).WithMany();
+        }
+    }
+}
+```
+
+
+## 数据库连接字符串
+
+```json
+{
+  "ConnectionStrings": {
+    "ProductDatabase": "Host=localhost;Port=5432;Database=ProductService;Username=postgres;Password=postgres"
+  }
+}
+```
+
+## 注册数据库上下文
+
+```csharp
+builder.Services.AddDbContext<ProductServiceDbContext>(options =>
+{
+    options.UseNpgsql(builder.Configuration.GetConnectionString(DbConstants.ConnectionStringName));
+});
+```
+
+## 迁移数据库
+
+```shell
+dotnet tool install --global dotnet-ef
+dotnet add package Microsoft.EntityFrameworkCore.Design
+```
+
+```shell
+dotnet ef migrations add InitialCreate --output-dir EntityFrameworks/Migrations
+dotnet ef database update
+```
+
+## 创建模型
+    
+```csharp
+namespace HelloWorld.ProductService.Models.Products
+{
+    public class ProductCreateRequest
+    {
+        public required string Name { get; init; }
+
+        public string? Description { get; init; }
+
+        public decimal Price { get; init; }
+
+        public int BrandId { get; init; }
+
+        public string? ImageUrl { get; init; }
+    }
+}
+```
+
+## 创建自动映射
+    
+```csharp
+namespace HelloWorld.ProductService.AutoMapper
+{
+    public class ProductsMapConfiguration : Profile
+    {
+        public ProductsMapConfiguration()
+        {
+            CreateMap<ProductCreateRequest, Product>();
+            CreateMap<ProductUpdateRequest, Product>();
+            CreateMap<Product, ProductListItem>().AfterMap((src, dest) => dest.BrandName = src.Brand.Name);
+            CreateMap<Product, ProductDetailsResponse>();
+
+            CreateMap<BrandCreateRequest, Brand>();
+            CreateMap<BrandUpdateRequest, Brand>();
+            CreateMap<Brand, BrandDetailsResponse>();
+            CreateMap<Brand, BrandListItem>();
+        }
+    }
+}
+```
+
+## 创建验证器
+
+```csharp
+namespace HelloWorld.ProductService.Validations.Products
+{
+    public class BrandUpdateRequestValidator : AbstractValidator<BrandUpdateRequest>
+    {
+        public BrandUpdateRequestValidator()
+        {
+            RuleFor(x => x.Id).GreaterThan(0);
+            RuleFor(x => x.Name).NotNull().NotEmpty().Length(8, 32);
+        }
+    }
+}
+```
+
+## 创建控制器
+
+```csharp
+
+namespace HelloWorld.ProductService.Controllers
+{
+    [Route("api/[controller]")]
+    [ApiController]
+    public class ProductsController : ControllerBase
+}
+```
+
+## 定义权限
+
+```csharp
+namespace HelloWorld.ProductService.PermissionProviders
+{
+    public static class CatalogPermissions
+
+    public class CatalogPermissionDefiitionProvider : IPermissionDefinitionProvider
+}
+```
+
+## 权限本地化
+    
+```csharp
+CatalogPermissionDefinitionProvider.en-US.resx
+CatalogPermissionDefinitionProvider.zh-CN.resx
+```
+
+## 重复性工作
+
+重复性工作可以通过代码生成工具来减少，例如 Visual Studio 插件， T4 模板， Roslyn 等。
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