entity-framework - Entity Framework Core 全局动态查询过滤器

Question

我们正在使用 ef core 3.1我们想使用动态查询过滤器，我尝试了示例实现，但没有像我们预期的那样正常工作，过滤始终相同的租户 ID，我尝试在下面进行解释

 public class TestDbContext : DbContext
    {
      
        public DbSet<TenantUser> TenantUsers { get; set; }
      

        private readonly ITenantProvider _tenantProvider;

        private Guid? TenantId => _tenantProvider.TenantId;

        public TestDbContext (DbContextOptions<TestDbContext > options, ITenantProvider tenantProvider) : base(options)
        {
               _tenantProvider = tenantProvider;
        }


        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<TenantUser>()
                .HasQueryFilter(p => EF.Property<Guid>(p, "TenantId") == TenantId);
        }

    }

ITenantProvider 从 HttpContext header 返回 TenantId

此代码始终从第一个请求中过滤相同的租户 ID

更新:

 public class TenantProvider : ITenantProvider
    {
        private readonly IHttpContextAccessor _httpContextAccessor;

        public TenantProvider(IHttpContextAccessor httpContextAccessor)
        {
            _httpContextAccessor = httpContextAccessor;
        }

        public Guid? TenantId
        {
            get
            {
                if (_httpContextAccessor.HttpContext.Request.Headers.TryGetValue(HeaderNames.TenantId, out var tenantId) &&
                    Guid.TryParse(tenantId, out Guid parsedTenantId))
                {
                    return parsedTenantId;
                }
                return null;
            }
        }
    }

例如第一个请求 TenantId = 60000000-0000-0000-0000-000000000000此过滤器 => 60000000-0000-0000-0000-000000000000

第二个请求 TenantId = 10000000-0000-0000-0000-000000000000此过滤器 => 60000000-0000-0000-0000-000000000000

Answer 1

您还应该实现自定义 IModelCacheKeyFactory

public class MyModelCacheKeyFactory : IModelCacheKeyFactory
{
    public object Create(DbContext context)
    {
        if (context is TestDbContext testDbContext)
        {
            return (context.GetType(), testDbContext.TenantId);
        }
        return context.GetType();
    }
}

然后，你需要像这样替换

var builder = new DbContextOptionsBuilder<TestDbContext>();

builder.ReplaceService<IModelCacheKeyFactory, MyModelCacheKeyFactory>();

var context = new TestDbContext(builder.Options);

引用: https://learn.microsoft.com/en-us/dotnet/api/microsoft.entityframeworkcore.infrastructure.imodelcachekeyfactory