Hot Chocolate 构建 GraphQL .Net Core 服务

Hot Chocolate 是 .NET 平台下的一个开源组件库, 您可以使用它创建 GraphQL 服务, 它消除了构建成熟的 GraphQL 服务的复杂性, Hot Chocolate 可以连接任何服务或数据源，并创建一个有凝聚力的服务，为您的消费者提供统一的 API。

我会在 .NET 应用中使用 Hot Chocolate 组件来构建 GraphQL 服务, 让我们开始吧！

创建服务

•  创建一个GraphQL服务

        安装nuget包：        

        HotChocolate.AspNetCore // GraphQL -  HotChocolate实现包
        HotChocolate.Data.EntityFramework //HotChocolate-IQueryable 实现包
        HotChocolate.Subscriptions.Redis //redis订阅
        Microsoft.EntityFrameworkCore.SqlServer //orm ef sqlServer
        Microsoft.EntityFrameworkCore.Tools //ef 工具

        builder.Services.AddGraphQLServer()

使用Hot Chocolate

• 新增一个Query

        builder.Services.AddQueryType<MyQuery>()//一个Query，所有Query写在一起

public class MyQuery{[UseOffsetPaging][UseProjection][UseFiltering][UseSorting]public IQueryable<Superhero> GetSuperheroes([Service] ApplicationDbContext context) =>context.Superheroes;[UseOffsetPaging][UseProjection][UseFiltering][UseSorting]public IQueryable<Movie> GetMovies([Service] ApplicationDbContext context) =>context.Movies;[UseOffsetPaging][UseProjection][UseFiltering][UseSorting]public IQueryable<Superpower> GetSuperpowers([Service] ApplicationDbContext context) =>context.Superpowers;}

• 使用特性  搜索、排序、投影

         builder.Services.AddProjections()
         .AddFiltering()
        .AddSorting()
        .SetPagingOptions(new PagingOptions
        {
                    MaxPageSize = 10000,
                    DefaultPageSize = 10,
                    IncludeTotalCount = true
        });

• 创建多个Query，通过ExtendObjectType("Query")关联

.AddQueryType(q => q.Name("Query")).AddTypeExtension<SuperheroQuery>().AddTypeExtension<MovieQuery>().AddTypeExtension<SuperpowerQuery>()[ExtendObjectType("Query")]public class SuperheroQuery{[UseOffsetPaging][UseProjection]//始终显示的数据字段，无论是否查询该字段[UseFiltering][UseSorting][GraphQLDescription("获取超级英雄集合")]public IQueryable<Superhero> GetSuperheroes([Service] ApplicationDbContext context) =>context.Superheroes;}

• 创建Mutation&自定义错误信息

.AddMutationType(m => m.Name("Mutation")).AddTypeExtension<SuperheroMutation>()[ExtendObjectType("Mutation")]public class SuperheroMutation{public async Task<Boolean> AddSuperheroAsync(SuperheroDto superhero, [Service] ISuperheroRepository _repository, [Service] ITopicEventSender sender){var (Success, KeyId) = await _repository.AddSuperheroAsync(superhero);await sender.SendAsync("SuperheroModified", superhero);return Success;}[Error(typeof(NameTakenException))]public async Task<Boolean> UpdateSuperheroAsync([ID] Guid Id, string name, [Service] ISuperheroRepository _repository, [Service] ITopicEventSender sender){var Success = await _repository.UpdateSuperheroAsync(Id, name);await sender.SendAsync("SuperheroModified", new SuperheroDto{Id = Id,Name = name,Description = "",Height = 0,Movies = null,Superpowers = null});return Success;}}public class NameTakenException : Exception{public NameTakenException(string username): base($"The name {username} is already taken."){}}

• 创建指令

.AddDirectiveType<ToUpperDirectiveType>().AddType<toLowerDirective>()/// <summary>/// 转大写指令/// </summary>public class ToUpperDirectiveType : DirectiveType{protected override void Configure(IDirectiveTypeDescriptor descriptor){descriptor.Name("toupper");//descriptor.Argument("name").Type<NonNullType<StringType>>();descriptor.Location(DirectiveLocation.Field);//https://chillicream.com/docs/hotchocolate/v13/execution-engine/field-middleware/#field-middleware-as-a-class//中间件 descriptor.Use((next, directive) =>{return async context =>{await next(context);if (context.Result is string str){context.Result = str.ToUpper();}else{context.ReportError("Bad Request.");context.OperationResult.SetResultState(WellKnownContextData.HttpStatusCode, 500);}};});}}/// <summary>/// 转小写指令/// 属性模式/// </summary>[DirectiveType(DirectiveLocation.Field)][toLowerDirectiveMiddleware]public class toLowerDirective{}/// <summary>/// 指令中间件/// </summary>public class toLowerDirectiveMiddlewareAttribute : DirectiveTypeDescriptorAttribute{protected override async void OnConfigure(IDescriptorContext context, IDirectiveTypeDescriptor descriptor, Type type){descriptor.Use((next, directive) =>{return async context =>{await next(context);if (context.Result is string str){context.Result = str.ToLower();}else{context.ReportError("Bad Request.");context.OperationResult.SetResultState(WellKnownContextData.HttpStatusCode, 500);}};});}}

•  创建订阅（通过webSocket方式）

.AddInMemorySubscriptions()//.AddRedisSubscriptions((sp) => ConnectionMultiplexer.Connect("127.0.0.1:6379,password=Michael,defaultDatabase=2")).AddSubscriptionType(q => q.Name("Subscription")).AddTypeExtension<SuperheroSubscribe>()//.AddSubscriptionType<SuperheroSubscribe>()//指定一个订阅类，所有订阅写在一起[ExtendObjectType("Subscription")]public class SuperheroSubscribe{[Subscribe][Topic("SuperheroUpdated")]public async Task<SuperheroDto> SuperheroUpdated([EventMessage] SuperheroDto superherodto, [Service] ISuperheroRepository _repository){var ret = await _repository.UpdateSuperheroAsync(superherodto.Id, $"{superherodto.Name}_{DateTime.Now.ToString("yyMMdd")}");superherodto.Description = "Subscribe-SuperheroModified";return superherodto;}#region 混合模式（订阅逻辑和解析器分离）/// <summary>/// 数据逻辑处理/// </summary>/// <param name="receiver"></param>/// <returns></returns>public async IAsyncEnumerable<SuperheroDto> SubscribeToSuperheroDto([Service] ITopicEventReceiver receiver, [Service] ISuperheroRepository _repository){yield return new SuperheroDto { Id = Guid.NewGuid(), Name = $"Name-{DateTime.Now.ToString("HHmmss")}" };//return ISourceStream<SuperheroDto>var source = await receiver.SubscribeAsync<SuperheroDto>("SuperheroModified");Task.Delay(3000);await foreach (SuperheroDto superherodto in source.ReadEventsAsync()){superherodto.Name = $"{superherodto.Name}_{DateTime.Now.ToString("HHmmss")}";var ret = await _repository.UpdateSuperheroAsync(superherodto.Id, superherodto.Name);yield return superherodto;}}/// <summary>/// 订阅/// 服务端必须开启websocket/// 订阅人监听websocket/// </summary>/// <param name="superherodto"></param>/// <param name="_repository"></param>/// <returns></returns>[Topic("SuperheroModified")][Subscribe(With = nameof(SubscribeToSuperheroDto))]public async Task<SuperheroDto> SuperheroModified([EventMessage] SuperheroDto superherodto){return superherodto;}#endregion}

必须先链接WebSocket，Mutation事件才会推送 ，GraphQL语法

subscription{superheroUpdated {idnamedescription}
}

 Promgram 整体配置

 var builder = WebApplication.CreateBuilder(args);Microsoft.Extensions.Configuration.ConfigurationManager configuration = builder.Configuration;// Add services to the container.builder.Services.AddControllers();// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbucklebuilder.Services.AddEndpointsApiExplorer();builder.Services.AddSwaggerGen();builder.Services.AddGraphQLServer().AddInMemorySubscriptions()//.AddRedisSubscriptions((sp) => ConnectionMultiplexer.Connect("127.0.0.1:6379,password=Michael,defaultDatabase=2")).AddSubscriptionType(q => q.Name("Subscription")).AddTypeExtension<SuperheroSubscribe>()//.AddSubscriptionType<SuperheroSubscribe>()//指定一个订阅类，所有订阅写在一起//.AddTypeExtensionsFromFile("./Stitching.graphql")//.ModifyOptions(options =>//{//    /*//     * code-first模式-Explicit:显示绑定(手动绑定字段，或者使用ObjectType<T>-override Configure手动设置)//     * 显示绑定 必须所有数据都要声明包括 Tsortinput，Tinput，TOperationFilterInput等。。。//     * Annotation-based模式-Implicit:隐式绑定(默认展示所有字段，或者使用ObjectType<T>-override Configure手动设置)//     * GraphQLIgnoreAttribute 可过滤不需要的字段//     *///    options.DefaultBindingBehavior = BindingBehavior.Explicit;//}).AddType<SuperheroType>().AddType<MovieType>().AddType<SuperpowerType>()//.AddQueryType<MyQuery>()//一个Query，所有Query写在一起.AddQueryType(q => q.Name("Query")).AddTypeExtension<SuperheroQuery>().AddTypeExtension<MovieQuery>().AddTypeExtension<SuperpowerQuery>().AddMutationType(m => m.Name("Mutation")).AddTypeExtension<SuperheroMutation>().AddProjections().AddFiltering().AddSorting().SetPagingOptions(new PagingOptions{MaxPageSize = 10000,DefaultPageSize = 10,IncludeTotalCount = true}).AddDirectiveType<MyDirectiveType>().AddDirectiveType<ToUpperDirectiveType>().AddType<toLowerDirective>();string appRoot = builder.Environment.ContentRootPath;Environment.SetEnvironmentVariable("AppDataDirectory", System.IO.Path.Combine(appRoot, "App_Data"));var SqlServerConnStr = Environment.ExpandEnvironmentVariables(configuration.GetConnectionString("SqlServer"));// Add Application Db Context optionsbuilder.Services.AddDbContext<ApplicationDbContext>(options =>options.UseSqlServer(SqlServerConnStr));// Register custom services for the superheroesbuilder.Services.AddScoped<ISuperheroRepository, SuperheroRepository>();builder.Services.AddScoped<ISuperpowerRepository, SuperpowerRepository>();builder.Services.AddScoped<IMovieRepository, MovieRepository>();var app = builder.Build();// Configure the HTTP request pipeline.if (app.Environment.IsDevelopment()){app.UseSwagger();app.UseSwaggerUI();}app.UseHttpsRedirection();app.UseAuthorization();app.MapControllers();//使用GraphQL-Subscription 必须开启websocketapp.UseWebSockets();//https://blog.christian-schou.dk/how-to-implement-graphql-in-asp-net-core/app.MapGraphQL();app.Run();

•  https://localhost:7199/graphql/

 

通过Strawberry Shake，自动链接GraphQL服务，创建客户端

 Introduction - Strawberry Shake - ChilliCream GraphQL Platform

 NSwagStudio，通过Swagger.json 文档创建 TypeScript Client、CSharp Client、CSharp Controller

NSwagStudio · RicoSuter/NSwag Wiki · GitHub