使用linq选择参考表的特定字段 [英] Select specific field of reference table using linq

问题描述

嗨

i有书桌，每本书都有很多章。

i为我的实体创建以下课程

hi
i have book table and each book have many chapter
i create below class for my entity

public class Book
    {
        [Key]
        public int BookID { get; set; }

        [MinLength(10,ErrorMessage = "ISBN Minimum size should be 10"),MaxLength(13,ErrorMessage = "Maximum Lenght of ISBN should be 13 ")]
        public string ISBN { get; set; }
        public string bookName { get; set; }
        public string bookSummery { get; set; }
        public string bookAuthor { get; set; }

        public string bookTranslator { get; set; }
        
    
        public virtual ICollection<Chapter> Chapters { get; set;}

    }


 public class Chapter
    {
        public int ChapterId { get; set; }

        public string chapterName { get; set; }

        [ForeignKey("Book")]
        public int BookRefId { get; set; }
        public virtual Book Book { get; set; }
    }

i只想选择我章节的特定字段（在这个例子中只有chapterName）



我尝试过：

i want to just select specific field of my chapter(in this exampe only chapterName)

What I have tried:

<pre>var _books = (from _b in db.Books
                          select new
                          {
                              _b.ISBN,
                              _b.BookID,
                             _b.bookName,
                             _b.bookSummery,
                             _b.Chapters = _b.Chapters.Select(details => new {
             
                                  details.chapterName,
                                 
                              },
                          });

但这段代码对我不起作用

but this code dont work for me

推荐答案

我发现解决方案

i find solution

var _books = (from _b in db.Books
                         select new
                         {
                             _b.bookAuthor,
                             _b.bookCountry,
                             _b.BookID,
                             _b.bookName,
                             _b.bookTranslator,
                             _b.bookImage,
                             _b.bookPrice,
                             _b.bookTotalTime,
                             _b.Category,
                             chapters = from _ch in _b.Chapters
                                        select new
                                        {
                                            _ch.ChapterId,
                                           _ch.chapterName

                                        }
                         });

这解决了我的问题。

this solve me problem.

这篇关于使用linq选择参考表的特定字段的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！