我正在将POCO映射到模型,代码如下所示.
// NOT NEEDED var noneRequiredUserDocuments = new List<NoneRequiredUserDocument>();
//var docs = studentDocuments.Where(x => x.RequiredUserDocumentId == null); // NOT NEEDED .ToList();
//var noneRequiredUserDocuments = docs.Select(x => new NoneRequiredUserDocument
// You can chain LINQ methods (i.e. Where and Select)
var noneRequiredUserDocuments = studentDocuments
.Where(x => x.RequiredUserDocumentId == null)
.Select(x => new NoneRequiredUserDocument
{
StudentDocument = x,
Src = _storageService.GetFileUrl(x.FileName),
ThumbnailImageUrl = ImageHelper.ThumbnailImageUrl(Src, 75)
}).ToList();
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我的问题是在这一行:
ThumbnailImageUrl = ImageHelper.ThumbnailImageUrl(Src, 75)
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Src
在上下文中不存在.
有没有办法让我在select中声明一个我可以在LINQ select中重用的变量?
而且我不想打_storageService.GetFileUrl
两次电话.
Rah*_*ngh 43
你可以在这里声明一个变量Select
: -
noneRequiredUserDocuments = docs.Select(x =>
{
var src= _storageService.GetFileUrl(x.FileName);
return new NoneRequiredUserDocument
{
StudentDocument = x,
Src = src,
ThumbnailImageUrl = ImageHelper.ThumbnailImageUrl(src, 75);
};
}).ToList();
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在query syntax
做这相当于: -
from x in docs
let src= _storageService.GetFileUrl(x.FileName)
select and so on..
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Tse*_*sef 10
您可以使用"let"关键字:
var list = (from x in docs
let temp = _storageService.GetFileUrl(x.FileName)
select new NoneRequiredUserDocument
{
StudentDocument = x,
Src = temp,
ThumbnailImageUrl = ImageHelper.ThumbnailImageUrl(temp, 75)
}).ToList();
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您可以创建一个常规代码块,而不是在lambda表达式中运行单个语句,这样您就可以声明一个变量"src",它将在整个块中可用 - 遵循常规范围规则.
noneRequiredUserDocuments = docs.Select(x => {
var src = _storageService.GetFileUrl(x.FileName);
return
new NoneRequiredUserDocument
{
StudentDocument = x,
Src = src,
ThumbnailImageUrl = ImageHelper.ThumbnailImageUrl(Src, 75)
};
}).ToList();
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