$ dotnet add src/TodoList.Application/TodoList.Application.csproj package MediatR.Extensions.Microsoft.DependencyInjection

using System.Reflection;

using Microsoft.Extensions.DependencyInjection;



namespace TodoList.Application;



public static class DependencyInjection

{

    public static IServiceCollection AddApplication(this IServiceCollection services)

    {

        services.AddMediatR(Assembly.GetExecutingAssembly());

        return services;

    }

}

// 省略其他...
// 添加應(yīng)用層配置
builder.Services.AddApplication();
// 添加基礎(chǔ)設(shè)施配置
builder.Services.AddInfrastructure(builder.Configuration);

using MediatR;

using TodoList.Application.Common.Interfaces;



namespace TodoList.Application.TodoLists.Commands.CreateTodoList;



public class CreateTodoListCommand : IRequest<Guid>

{

    public string? Title { get; set; }

}



public class CreateTodoListCommandHandler : IRequestHandler<CreateTodoListCommand, Guid>

{

    private readonly IRepository<Domain.Entities.TodoList> _repository;



    public CreateTodoListCommandHandler(IRepository<Domain.Entities.TodoList> repository)

    {

        _repository = repository;

    }



    public async Task<Guid> Handle(CreateTodoListCommand request, CancellationToken cancellationToken)

    {

        var entity = new Domain.Entities.TodoList

        {

            Title = request.Title

        };



        await _repository.AddAsync(entity, cancellationToken);

        return entity.Id;

    }

}

using MediatR;

using Microsoft.AspNetCore.Mvc;

using TodoList.Application.TodoLists.Commands.CreateTodoList;



namespace TodoList.Api.Controllers;



[ApiController]

[Route("/todo-list")]

public class TodoListController : ControllerBase

{

    private readonly IMediator _mediator;



    // 注入MediatR

    public TodoListController(IMediator mediator)

        => _mediator = mediator;



    [HttpPost]

    public async Task<Guid> Create([FromBody] CreateTodoListCommand command)

    {

        var createdTodoList = await _mediator.Send(command);



        // 出于演示的目的，這里只返回創(chuàng)建出來的TodoList的Id，

        // 實際使用中可能會選擇IActionResult作為返回的類型并返回CreatedAtRoute對象，

        // 因為我們還沒有去寫GET方法，返回CreatedAtRoute會報錯（找不到對應(yīng)的Route），等講完GET后會在那里更新

        return createdTodoList.Id;

    }

}

using MediatR;

using TodoList.Application.Common.Interfaces;

using TodoList.Domain.Entities;

using TodoList.Domain.Events;



namespace TodoList.Application.TodoItems.Commands.CreateTodoItem;



public class CreateTodoItemCommand : IRequest<Guid>

{

    public Guid ListId { get; set; }



    public string? Title { get; set; }

}



public class CreateTodoItemCommandHandler : IRequestHandler<CreateTodoItemCommand, Guid>

{

    private readonly IRepository<TodoItem> _repository;



    public CreateTodoItemCommandHandler(IRepository<TodoItem> repository)

    {

        _repository = repository;

    }



    public async Task<Guid> Handle(CreateTodoItemCommand request, CancellationToken cancellationToken)

    {

        var entity = new TodoItem

        {

            // 這個ListId在前文中的代碼里漏掉了，需要添加到Domain.Entities.TodoItem實體上

            ListId = request.ListId,

            Title = request.Title,

            Done = false

        };



        await _repository.AddAsync(entity, cancellationToken);



        return entity.Id;

    }

}

using MediatR;

using Microsoft.AspNetCore.Mvc;

using TodoList.Application.TodoItems.Commands.CreateTodoItem;



namespace TodoList.Api.Controllers;



[ApiController]

[Route("/todo-item")]

public class TodoItemController : ControllerBase

{

    private readonly IMediator _mediator;



    // 注入MediatR

    public TodoItemController(IMediator mediator) 

        => _mediator = mediator;



    [HttpPost]

    public async Task<Guid> Create([FromBody] CreateTodoItemCommand command)

    {

        var createdTodoItem = await _mediator.Send(command);



        // 處于演示的目的，這里只返回創(chuàng)建出來的TodoItem的Id，理由同前

        return createdTodoItem.Id;

    }

}