Question

我正在Asp.net Core 2.1（EF，MVC，SQL Server）中做一个项目，通常我正在做类似以下的事情来获取当前用户（即所有者）的记录：

        [HttpPost]
        [Authorize]
        public JsonResult GetOrders()
        {
            string userId = _userManager.GetUserId(User);

            var applicationDbContext = _context.Order
                .Where(m => m.UserID == userId);
               ...etc...
         }

但是，我想知道是否有一种更广泛的（对于控制器，甚至是更全局的）结果过滤器，而不是必须在每个方法中包括上面的代码？

我很不高兴尝试了这个

        public OrderController(ApplicationDbContext context, IAuthorizationService authorizationService, UserManager<IdentityUser> userManager)
        {
            _authorizationService = authorizationService;
            _userManager = userManager;

            string userId = _userManager.GetUserId(User);
            _context = context.Where(m => m.UserID == userId);
        }

我有点理解为什么这行不通。但是，基本上，我的整个项目将精炼到所有者，很高兴只在一个地方指定它，然后知道_context（或ApplicationDbContext？或其他适当方法）已经包括了所有者记录。

Answer 1

请尝试使用EF Core 2.0中针对此用例引入的Global Query Filters。

Answer 2

有两个部分可以满足您的要求，一个是实现Global Query Filters，另一个是将UserId传递给Global Query Filters。

我建议您按照以下步骤操作：

Moidfy the DbContexxt

 public class ApplicationDbContext : IdentityDbContext
{
    protected virtual string CurrentUserId
    {
        get
        {
            return Users.FirstOrDefault(u => u.UserName == _contextAccessor.HttpContext.User.Identity.Name)?.Id;
        }
    }
    private readonly IHttpContextAccessor _contextAccessor;
    private readonly UserResolverService _userResolverService;
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options
         , IHttpContextAccessor contextAccessor
        )
        : base(options)
    {
        _contextAccessor = contextAccessor;
    }
    public DbSet<Order> Orders { get; set; }

    private static MethodInfo ConfigureGlobalFiltersMethodInfo = typeof(ApplicationDbContext).GetMethod(nameof(ConfigureGlobalFilters), BindingFlags.Instance | BindingFlags.NonPublic);

    protected override void OnModelCreating(ModelBuilder builder)
    {
        //Configure Query Filter
        foreach (var entityType in builder.Model.GetEntityTypes())
        {
            ConfigureGlobalFiltersMethodInfo
                .MakeGenericMethod(entityType.ClrType)
                .Invoke(this, new object[] { builder, entityType });
        }

        base.OnModelCreating(builder);            
    }

    protected void ConfigureGlobalFilters<TEntity>(ModelBuilder builder, IMutableEntityType entityType)
                        where TEntity : class
    {
        Expression<Func<TEntity, bool>> expression = null;
        if (typeof(IEntityBase).IsAssignableFrom(typeof(TEntity)))
        {
            expression = e => ((IEntityBase)e).UserId == CurrentUserId;
            builder.Entity<TEntity>().HasQueryFilter(expression);
        }
    }
}

通过下面的代码
注册IHttpContextAccessor
```
    services.AddHttpContextAccessor();
```

为了集中控制UserId过滤器，我定义了IEntityBase
//IEntityBase.cs

 public interface IEntityBase    {
    string UserId { get; set; }
    IdentityUser User { get; set; }
 }

//订单

    public class Order: IEntityBase
{
    public string Id { get; set; }
    public string OrderNo { get; set; }
    public string UserId { get; set; }
    public IdentityUser User { get; set; }
    public string Description { get; set; }
}

在控制器（或更高）级别而不是方法级别，将SQL结果缩小给所有者

2 个答案: