在WPF和EF 6中，如何只显示类的字段的子集？ [英] In WPF and EF 6, how can I display only a subset of the fields of a class?

问题描述

na WPF应用程序，它也使用Entity Framework 6，我想只显示一个类的字段的子集，但我不清楚如何执行此操作。
在应用程序的主窗口中，Window_Loaded方法包含以下代码，它为类Course的所有字段提供表格显示，但我只想加载并显示字段的子集。这是当前代码：

 private void Window_Loaded（object sender，RoutedEventArgs e）
 {
 System.Windows.Data .CollectionViewSource courseViewSource =（（System.Windows.Data.CollectionViewSource）（this.FindResource（" courseViewSource"）））;; 
 
 _context.Courses.Include（c => c.Author）.Load（）; 
 courseViewSource.Source = _context.Courses.Local; 
 
} 

所以，我不想加载课程的字段，但是我在哪里放Select（）？

此致，

Juan Dent

---

Juan Dent

解决方案

这是使用Linq投影调用，您可以使用anaymous类型，只读，类型或读/写的自定义类型来设置要从Linq查询返回的对象。

https： //csharp-station.com/Tutorial/Linq/Lesson02

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-结构/匿名类型

 

n a WPF application that also uses Entity Framework 6, I want to display only a subset of the fields of a class, but it is not clear to me how to do this. In the main window of the application, the Window_Loaded method contains the following code that provides a table display for all the fields of the class Course but I want to just load and display a subset of the fields. This is the current code:

private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        System.Windows.Data.CollectionViewSource courseViewSource = ((System.Windows.Data.CollectionViewSource)(this.FindResource("courseViewSource")));

        _context.Courses.Include(c => c.Author).Load();
        courseViewSource.Source = _context.Courses.Local;

    }

So, I don't want to load fields of Courses, but where do I put the Select()?

Regards,

Juan Dent

---

Juan Dent

解决方案

It's called using a Linq projection where you shape the object you want returned from the Linq query by using an anaymous type , read only, type or a custom type that is read/write.

https://csharp-station.com/Tutorial/Linq/Lesson02

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/anonymous-types

 

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