System.Linq.Dynamic 不适用于实体框架

发布于 2024-10-14 11:08:56 字数 1138 浏览 1 评论 0原文

我正在尝试使用此处发布的 LINQ 动态查询库 - http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq -dynamic-query-library.aspx

它应该也适用于 EF，但我无法让它满足该要求。

以下效果很好：

List<string> paramsList = new List<string> {"CustomerID"};
        var customer =
            ctx.Customers.Where(cus=>cus.CompanyName.Contains("A")).Select("new(" +
                                 string.Join(", ", paramsList.ToArray()) +
                                 ")");

但是，如果我省略“Where”子句并执行类似的操作，

List<string> paramsList = new List<string> {"CustomerID"};
        var customer =
            ctx.Customers.Select("new(" +
                                 string.Join(", ", paramsList.ToArray()) +
                                 ")");

则会出现以下错误：

“new”无法解析为有效的类型构造函数或函数。、近函数、方法或类型构造函数

如果我使用 Linq2Sql 而不是 Linq2Entities，它会完美地工作。

我在这里缺少什么？

原文

I'm trying to use the LINQ Dynamic Query Library posted here - http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx

It is supposed to work for the EF too but I can't get it to fulfill that claim.

The following works great:

List<string> paramsList = new List<string> {"CustomerID"};
        var customer =
            ctx.Customers.Where(cus=>cus.CompanyName.Contains("A")).Select("new(" +
                                 string.Join(", ", paramsList.ToArray()) +
                                 ")");

However if I omit the "Where" clause and do something like this

List<string> paramsList = new List<string> {"CustomerID"};
        var customer =
            ctx.Customers.Select("new(" +
                                 string.Join(", ", paramsList.ToArray()) +
                                 ")");

I get the following error: