除了 dbContext 之外，如何向 Blazor 中的服务添加参数？

Question

VS2022 网核 6 EF 6

    builder.Services.AddDbContext<MyAppDbContext>(options removed for simplicity)

    //This is my service registered on Program.cs:
    builder.Services.AddScoped<AccountService>();
    
    //This is the existing class that works as expected:
    public class AccountService
    {
     private readonly MyAppDbContext _context;  
     public AccountService(MyAppDbContext context)
       {
          _context = context;
       }
    }
    //So far so good... 
    
    // Now I need to add another parameter to the service:
    public class AccountService
    {
     private readonly MyAppDbContext _context;  
     public AccountService(MyAppDbContext context, string newParameter)
       {
          _context = context;
          string temp = newParameter;
       }
    }
    
    // But I cannot register; I don't know what to put as first value and if I put MyAppDbContext it gives an error saying it is a type.
    
    builder.Services.AddScoped(ServiceProvider => { return new AccountService(??, newParameter);});

// This works (no compile error) for newParameter but ignores DbContext
    builder.Services.AddScoped(ServiceProvider => { return new AccountService( **null**, newParameter);});

Answer 1

你注册会变得丑一点：

builder.Services.AddScoped<AccountService>(x => new AccountService( 
     x.GetRequiredService<MyAppDbContext>(),
     newParameter));

每次您需要 AccountService 时，让 ServiceProvider 创建（范围内的）DbContext 很重要。