Question

我如何重构这个LINQ以使其工作？

var a =  (from app in mamDB.Apps where app.IsDeleted == false 
                select string.Format("{0}{1}",app.AppName, 
                app.AppsData.IsExperimental? " (exp)": string.Empty))
               .ToArray();}

我现在收到错误：

LINQ to Entities无法识别方法'System.String 格式化（System.String，System.Object，System.Object）'方法，以及此方法方法无法转换为商店表达式。

我无用地尝试过：

return (from app in mamDB.Apps where app.IsDeleted == false 
        select new string(app.AppName + (app.AppsData != null && 
        app.AppsData.IsExperimental)? " (exp)": string.Empty)).ToArray();

Answer 1

您可以在LINQ-to-Objects中执行string.Format：

var a =  (from app in mamDB.Apps where app.IsDeleted == false 
         select new {app.AppName, app.AppsData.IsExperimental})
         .AsEnumerable()
         .Select(row => string.Format("{0}{1}",
            row.AppName, row.IsExperimental ? " (exp)" : "")).ToArray();

Answer 2

试试这个

var a =  (from app in mamDB.Apps where app.IsDeleted == false 
            select new {AppName = app.AppName, IsExperimental = app.AppsData.IsExperimental})
          .Select(app => string.Format("{0}{1}",app.AppName, 
            app.IsExperimental? " (exp)": string.Empty))
           .ToArray();}

LINQ to Entities无法识别方法'System.String Format

2 个答案: