从ObjectDataSource业务类返回自定义可枚举类型 [英] Returning a custom enumerable type from ObjectDataSource business class

问题描述

这个问题可能看起来很基本但我对C＃的这些方面真的很新。我很抱歉。



我正在使用ASP.NET 4 Web窗体应用程序。



这是我的书桌



预订

--------------- ---

BookID（pk）

BookName

授权书

主题ID

副本





这是我的作者表



作者

-----------

AuthorID（pk）

作者姓名







主题表



主题

---------------

SubjectID（pk）

主题名称





我从数据库中的这些表生成了ADO.NET模型类。



我为我的Book模型创建了一个Business Class（包含CRUD方法），这样我就可以使用ObjectDataSource在Book上执行CRUD操作。



这是获取我的商务舱的方法

This question might seem very basic but I am really very new to these aspects of C#. My apologies.

I am working on a ASP.NET 4 Web Forms application.

Here is my Book table

Book
------------------
BookID (pk)
BookName
AuthorID
SubjectID
Copies


Here is my Author table

Author
-----------
AuthorID(pk)
AuthorName



Subject table

Subject
---------------
SubjectID(pk)
SubjectName


I have generated ADO.NET Model classes from these tables in the database.

I have created a Business Class for my Book model (containing CRUD methods) so that I can use an ObjectDataSource to perform CRUD operations on Book.

Here is the get method of my Business Class

public static IEnumerable<Book> GetAllBooks()
    {
        var result = from author in db.Authors
                 join book in db.Books on new { AuthorID = author.AuthorID } equals new { AuthorID = book.AuthorID }
                 join subject in db.Subjects on new { SubjectID = book.SubjectID } equals new { SubjectID = subject.SubjectID }
                 select new { BookID = book.BookID, BookName = book.BookName, Copies = book.Copies, AuthorName = author.AuthorName };


        return result.ToList();
    }

此方法的返回类型是IEnumerable但是因为我返回了现在匿名对象列表，这个返回类型是无效的。



我知道我可以通过扩展Book模型类来解决这个问题，使它包含AuthorName和SubjectName，然后使用该模型类，但我想避免编写更多代码。



有没有其他方法可以返回这个匿名对象列表？

The return type of this method is IEnumerable but since I am returning a list of anonymous objects now, this return type is invalid.

I know I can solve this by extending the Book model class so that it contains AuthorName and SubjectName, and then using that model class, but I want to avoid writing more code.

Is there any other way I can return this anonymous object list?

推荐答案

我会创建如下的新类

I would create new class like below

public class BookWithAuthorName 
{
    public int BookID { get; set; }
    // add all properties of Book and
    public string AuthorName { get; set; }
}

你的方法没有类型安全返回类型

no you have type safe returning type for your method

public static IEnumerable<bookwithauthorname> GetAllBooks()
{
    var result = from author in db.Authors
             join book in db.Books on new { AuthorID = author.AuthorID } equals new { AuthorID = book.AuthorID }
             join subject in db.Subjects on new { SubjectID = book.SubjectID } equals new { SubjectID = subject.SubjectID }
             select new BookWithAuthorName{ BookID = book.BookID, BookName = book.BookName, Copies = book.Copies, AuthorName = author.AuthorName };


    return result.ToList();
}

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