錯誤的LINQ查詢透視

Question

當執行使用LINQ到實體的「鍵/值表」下面的查詢，我得到一個[System.NotSupportedException] "Specified method not supported"：

有人可以給我一個提示我做錯了嗎？

var Pivot = context.goe_postmeta.GroupBy(pm => pm.post_id).Select(
       g => new PivotTemp 
        { 
         ID = g.Key, 
         FirstName = g.FirstOrDefault(p => p.meta_key == "_billing_first_name").meta_value, 
         LastName = g.FirstOrDefault(p => p.meta_key == "_billing_last_name").meta_value, 
         Address = g.FirstOrDefault(p => p.meta_key == "_billing_address_1").meta_value, 
         PostCode = g.FirstOrDefault(p => p.meta_key == "_billing_postcode").meta_value, 
         Phone = g.FirstOrDefault(p => p.meta_key == "_billing_phone").meta_value, 
         OrderTotal = g.FirstOrDefault(p => p.meta_key == "_order_total").meta_value, 
         PickupLocation = g.FirstOrDefault(p => p.meta_key == "_pickup_location").meta_value, 
         PickupTime = g.FirstOrDefault(p => p.meta_key == "_pickup_time").meta_value, 
         OrderItems = g.FirstOrDefault(p => p.meta_key == "_order_items").meta_value 
        }).ToList(); 

Answer 1

var Pivot = context.goe_postmeta.GroupBy(pm => pm.post_id).Select(
       g => new PivotTemp 
        { 
         ID = g.Key, 
         FirstName = g.FirstOrDefault(p => p.meta_key == "_billing_first_name").meta_value, 
         LastName = g.FirstOrDefault(p => p.meta_key == "_billing_last_name").meta_value, 
         Address = g.FirstOrDefault(p => p.meta_key == "_billing_address_1").meta_value, 
         PostCode = g.FirstOrDefault(p => p.meta_key == "_billing_postcode").meta_value, 
         Phone = g.FirstOrDefault(p => p.meta_key == "_billing_phone").meta_value, 
         OrderTotal = g.FirstOrDefault(p => p.meta_key == "_order_total").meta_value, 
         PickupLocation = g.FirstOrDefault(p => p.meta_key == "_pickup_location").meta_value, 
         PickupTime = g.FirstOrDefault(p => p.meta_key == "_pickup_time").meta_value, 
         OrderItems = g.FirstOrDefault(p => p.meta_key == "_order_items").meta_value 
        }).ToList(); 

也許是因爲你缺少的 「」 ToList（）之前？只是一個猜測