使用 LINQ 按 IList 的內容過濾 DbSet

Question

我有 2 個 ILists 供應商和 VwSrmAhmSuppliers。 它們都是從數據庫中查詢的。 我先填寫供應商。 然后，當我查詢 VwSrmAhmSuppliers 時，我想根據我已經在供應商中提取的內容過濾結果。

public IList<Supplier> Suppliers { get;set; }
public IList<Models.ExternalData.VwSrmAhmSupplier> VwSrmAhmSuppliers { get; set; }

public async Task OnGetAsync(Boolean? All)
{
   //don't show all records unless explicity asked to!
   if (All == true)
   {
      Suppliers = await _context.Supplier
         .Include(s => s.Status)
         .Include(c => c.Category)
         .Include(c => c.Comments)
         .OrderByDescending(c => c.CreateDate)
         .ToListAsync();

      //these do not work
      //VwSrmAhmSuppliers = await _externalcontext.VwSrmAhmSuppliers.Where(d => Suppliers.Any(s=>s.SupplierNo == d.AhmSupplierNo)).ToListAsync();
      //VwSrmAhmSuppliers = await _externalcontext.VwSrmAhmSuppliers.Where(v => Suppliers.Any(s=> s.SupplierNo.Equals(v.AhmSupplierNo))).ToListAsync();

      //This does work, it gets all suppliers but it's too many
      //VwSrmAhmSuppliers = await _externalcontext.VwSrmAhmSuppliers.ToListAsync();


      VwSrmAhmSuppliers = await _externalcontext.VwSrmAhmSuppliers
         .Where(v => Suppliers
            .Any(s => s.SupplierNo == v.AhmSupplierNo))
         .ToListAsync();
   }
}

產生的錯誤是：

InvalidOperationException：無法翻譯 LINQ 表達式“DbSet .Where(v => __Suppliers_0 .Any(s => s.SupplierNo == v.AhmSupplierNo))”。 以可翻譯的形式重寫查詢，或通過插入對 AsEnumerable()、AsAsyncEnumerable()、ToList() 或 ToListAsync() 的調用顯式切換到客戶端評估。 有關詳細信息，請參閱https://go.microsoft.com/fwlink/?linkid=2101038 。

我不清楚。

Answer 1

您需要首先投影出簡單引用類型（ int 、 string等）的內存中集合，而不是類型Supplier的列表，然后將其用於您的Any或Contains條件，例如：

Suppliers = await _context.Supplier
         .Include(s => s.Status)
         .Include(c => c.Category)
         .Include(c => c.Comments)
         .OrderByDescending(c => c.CreateDate)
         .ToListAsync();

//Project out the required references
var supplierNos = Suppliers.Select(s => s.SupplierNo).ToList();

//Use the simple reference type collection in your query
VwSrmAhmSuppliers = await _externalcontext.VwSrmAhmSuppliers
    .Where(d => supplierNos.Any(s=> s == d.AhmSupplierNo)).ToListAsync();