我遇到以下代码问题。如果所有表都至少有一个值,则显示详细信息,但如果至少有一个表没有值,则显示任何内容。我收到了消息
序列不包含任何元素。
我的代码如下:
public sneakerDetails GetSneakerDetails(int id)
{
IQueryable<sneakerDetails> query = from sneaks in _context.sneakers
from image in _context.sneakerImages
from website in _context.sneakerWebsites
// from website in _context.sneakerWebsites
where sneaks.sneaker_id == id && image.sneaker_id == website.sneaker_id && sneaks.sneaker_id == website.sneake_id
select new sneakerDetails
{
//sneaker_id = sneaks.sneaker_id,
Colorway = sneaks.Colorway,
Name = sneaks.Name,
description = sneaks.description,
imageAlternative = image.imageAlternative,
release_date = sneaks.release_date,
imageB = image.imageB,
imageF = image.imageF,
imageL = image.imageL,
imageR = image.imageR,
website = website.website,
websiteLogo = website.websiteLogo
};
return query.ToList().First();
我尝试将返回值更改为FirstOrDefault
但是当我点击特定的运动鞋时,它只显示标题而没有数据。
我是否需要为两个表编写if
语句?
答案 0 :(得分:0)
尝试DefaultIfEmpty()
:
from sneaks in _context.sneakers.DefaultIfEmpty()
from image in _context.sneakerImages.DefaultIfEmpty()
from website in _context.sneakerWebsites.DefaultIfEmpty()
// from website in _context.sneakerWebsites
where sneaks.sneaker_id == id
&& image.sneaker_id == website.sneaker_id
&& sneaks.sneaker_id == website.sneake_id
select new sneakerDetails
{
//sneaker_id = sneaks.sneaker_id,
Colorway = sneaks.Colorway,
Name = sneaks.Name,
description = sneaks.description,
imageAlternative = image.imageAlternative,
release_date = sneaks.release_date,
imageB = image.imageB,
imageF = image.imageF,
imageL = image.imageL,
imageR = image.imageR,
website = website.website,
websiteLogo = website.websiteLogo
};