Question

我在下面有一个linq查询。我在其他3个地方有类似的查询，这显然不是很好。所以我想将tfID传递给方法。我知道你不能将var作为参数传递给方法。

 var tfID = from orderItem in _orderBlock.Orders
                            join assetItem in tfEntity.AssetDetails on orderItem.Security.ID equals assetItem.sISIN
                            where orderItem.IdenitfierUsed == "I"
                            where assetItem.iSkeletal == 1
                            select new { orderItem, assetItem };

我想将上面的查询更改为以下内容。但是，我得到的错误消息是“无法共谋转换类型”System.Collections.Generic.IEnumerable到'System.Collections.Generic.Dictionary'存在显式转换（您是否错过了转换）。

Dictionary<Order, AssetDetail> ordersDictionary = new Dictionary<Order, AssetDetail>();

        ordersDictionary = from orderItem in _orderBlock.Orders
                            join assetItem in tfEntity.AssetDetails on orderItem.Security.ID equals assetItem.sISIN
                            where orderItem.IdenitfierUsed == "I"
                            where assetItem.iSkeletal == 1
                            select new { orderItem, assetItem };

Answer 1

使用ToDictionary

Dictionary<Order, AssetDetail> ordersDictionary =  
    (from orderItem in _orderBlock.Orders
    join assetItem in tfEntity.AssetDetails on orderItem.Security.ID equals assetItem.sISIN
    where orderItem.IdenitfierUsed == "I"
    where assetItem.iSkeletal == 1
    select new { orderItem, assetItem })
    .ToDictionary(x => x.orderItem, x => x.assetItem);

Answer 2

ordersDictionary = (from orderItem in _orderBlock.Orders
                    join assetItem in tfEntity.AssetDetails on orderItem.Security.ID 
                    equals assetItem.sISIN
                        where orderItem.IdenitfierUsed == "I"
                        where assetItem.iSkeletal == 1
                        select new { orderItem, assetItem }
                   ).ToDictionary(x=>x.orderItem, x=>x.assetItem);

Answer 3

您可以使用ToDictionary（）方法将结果转换为字典。即。

Dictionary<Order, AssetDetail> ordersDictionary = new Dictionary<Order, AssetDetail>();

    ordersDictionary = (from orderItem in _orderBlock.Orders
                        join assetItem in tfEntity.AssetDetails on orderItem.Security.ID equals assetItem.sISIN
                        where orderItem.IdenitfierUsed == "I"
                        where assetItem.iSkeletal == 1
                        select new { orderItem, assetItem }).ToDictionary(key => //the key, value => the value);

Answer 4

我知道你不能将var作为参数传递给方法。

不正确 - var不是（必然）匿名类型 - 它只是让编译器决定类型是什么。

您需要做的只是添加ToDictionary()：

var tfID = (from orderItem in _orderBlock.Orders
                        join assetItem in tfEntity.AssetDetails on orderItem.Security.ID equals assetItem.sISIN
                        where orderItem.IdenitfierUsed == "I"
                        where assetItem.iSkeletal == 1
                        select new { orderItem, assetItem })
            .ToDictionary(i => orderItem, i => assetItem);

tfID将成为Dictionary<Order, AssetDetail>

C＃Linq查询返回类型到字典

4 个答案: