在 LINQ-to-Entities 查询中使用应用程序设置中指定的 StringCollection

发布于 2025-01-03 07:50:03 字数 478 浏览 2 评论 0原文

在我的应用程序中，我有 String.Collections.Specialized.StringCollection 类型的属性设置。它包含客户代码列表，例如 MSFT、SOF、IBM 等。我尝试在 where 子句中的 Linq-to-Entities 查询中使用它：

var ShippedOrders = dbcontext.Orders
 .Where(s=>(s.Status.Description.Equals("Shipped") && !Properties.Settings.Default.CustomersToExclude.Contains(s.CustomerCode)));

此操作失败，因为 Linq-to-Entities 无法识别 Contains类似于以下内容的消息：

“LINQ-to-Entities 无法识别方法 Contains...”

如何修改上面的代码以避免此错误？

原文

In my application, I have Property Setting which is of type String.Collections.Specialized.StringCollection. It contains a list of customer codes such as MSFT, SOF, IBM etc. I'm trying to use this in a Linq-to-Entities query in the where clause:

var ShippedOrders = dbcontext.Orders
 .Where(s=>(s.Status.Description.Equals("Shipped") && !Properties.Settings.Default.CustomersToExclude.Contains(s.CustomerCode)));

This fails as Contains is not recognized by Linq-to-Entities with a message similar to:

"LINQ-to-Entities does not recognize the method Contains...."

How do I revise the code above to avoid this error?

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演多会厌 2025-01-10 07:50:03

更短的路径是

myProperties.Settings.Default.CustomersToExclude.Cast<string>().Contains(blah);

对于集合本质上不支持 LINQ 的任何情况，这都是一个方便的技巧。

A shorter path is

myProperties.Settings.Default.CustomersToExclude.Cast<string>().Contains(blah);

That's a handy trick for any situation where a collection isn't inherently LINQ-aware.

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雨夜星沙 2025-01-10 07:50:03

由于您的问题被标记为 C# 4，请使用 List （StringCollection 很古老），并且您的查询应该可以工作。此外，您还应该在查询之外解析您的列表引用：

List<string> customersToExclude = ..
var ShippedOrders = dbcontext.Orders
                             .Where(s=>(s.Status.Description.Equals("Shipped") 
                                    && !customersToExclude.Contains(s.CustomerCode)));

编辑：

只需将您的客户复制到数组并使用它：

var customerstoExclude = new string[Properties.Settings.Default.CustomersToExclude.Count];
myProperties.Settings.Default.CustomersToExclude.CopyTo(customerstoExclude, 0);

Since your question is tagged as C# 4 use a List<string> instead (StringCollection is ancient) and your query should work. Also you should resolve your list reference outside your query:

List<string> customersToExclude = ..
var ShippedOrders = dbcontext.Orders
                             .Where(s=>(s.Status.Description.Equals("Shipped") 
                                    && !customersToExclude.Contains(s.CustomerCode)));

Edit:

Just copy your customers to an array and use that:

var customerstoExclude = new string[Properties.Settings.Default.CustomersToExclude.Count];
myProperties.Settings.Default.CustomersToExclude.CopyTo(customerstoExclude, 0);

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