我的 .NET 7 應用無法解析某個類型的服務。 已經添加到 DI

Question

如果我已經在 DI 中注冊了服務，我還缺少什么？

錯誤：

System.InvalidOperationException：在嘗試激活“Contoso.API.Controllers.AccountsController”時無法解析“Contoso.API.Services.AccountService”類型的服務。

在 Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService（IServiceProvider sp，類型類型，類型 requiredBy，Boolean isDefaultParameterRequired）
在 lambda_method136（閉包，IServiceProvider，對象 []）

Program.cs ：

builder.Services.AddDbContext<FinanceDbContext>(options => options.UseSqlServer(builder.Configuration.GetConnectionString("FinanceDb")));

builder.Services.AddScoped<IAccountService, AccountService>();

IAccountService.cs ：

public interface IAccountService
{
    Task<IList<Account>> GetAccountsAsync(string email);
}

AccountService.cs ：

public class AccountService : IAccountService
{
    private readonly FinanceDbContext _dbContext;

    public AccountService(FinanceDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    public async Task<IList<Account>> GetAccountsAsync(string email)
    {
        // Retrieve the user with the provided email address
        var user = await _dbContext.Users.Include(x => x.Accounts).FirstOrDefaultAsync(u => u.Email == email);

        // Return the user's accounts
        return user.Accounts;
    }
}

AccountsController.cs ：

public class AccountsController : ControllerBase
{
    private readonly IAccountService _accountService;

    public AccountsController(IAccountService accountService)
    {
        _accountService = accountService;
    }

    // GET: api/Accounts?email=test@example.com
    [HttpGet]
    public async Task<ActionResult<IList<Account>>> GetAccounts([FromQuery] string email)
    {
        // Retrieve the user's accounts based on the provided email address
        var accounts = await _accountService.GetAccountsAsync(email);

        // Return the list of accounts
        return Ok(accounts);
    }
}

我試過使用 DI 注冊服務

builder.Services.AddScoped<IAccountService, AccountService>(); 

但我仍然收到錯誤提示找不到服務

Answer 1

我想在 program.cs 文件中注入服務的順序可能會發生變化。

這是一個代碼片段，解釋了 program.cs 文件的順序。

var builder = WebApplication.CreateBuilder(args);

 
builder.Services.AddControllers();
// Add services 
builder.Services.AddDbContext<FinanceDbContext>(options => options.UseSqlServer(builder.Configuration.GetConnectionString("FinanceDb")));


builder.Services.AddScoped<IAccountService, AccountService>();


var app = builder.Build();

 
// add middlewares here

服務必須在 builder.Build() 之前注入； 之后只注入中間件。

希望這對你有幫助。