问题描述
到目前为止我得到的代码运行良好
The code I have got so far works fine
public async Task<ActionResult> Details(Guid? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
ItemDetailModel model = new ItemDetailModel();
model.Item = await db.Items.FindAsync(id);
if (model.Item == null)
{
return HttpNotFound();
}
return View(model);
}
但我想多包含 1 个表，不能使用 FindAsync
But I want to include 1 table more and cannot use FindAsync
public async Task<ActionResult> Details(Guid? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
ItemDetailModel model = new ItemDetailModel();
model.Item = await db.Items.Include(i=>i.ItemVerifications).FindAsync(id);
if (model.Item == null)
{
return HttpNotFound();
}
return View(model);
}
所以我遇到了这个错误
严重性代码描述项目文件行抑制状态错误 CS1061 'IQueryable' 不包含'FindAsync' 并且没有扩展方法 'FindAsync' 接受第一个可以找到IQueryable"类型的参数(您是否缺少使用指令还是程序集引用?)
Severity Code Description Project File Line Suppression State Error CS1061 'IQueryable' does not contain a definition for 'FindAsync' and no extension method 'FindAsync' accepting a first argument of type 'IQueryable' could be found (are you missing a using directive or an assembly reference?)
有什么办法解决吗?
推荐答案
最简单的就是用FirstOrDefaultAsync或者SingleOrDefaultAsync代替:
The simplest is to use FirstOrDefaultAsync or SingleOrDefaultAsync instead:
model.Item = await db.Items.Include(i => i.ItemVerifications)
.FirstOrDefaultAsync(i => i.Id == id.Value);
您收到错误的原因是因为 Find/FindAsync 方法是为 DbSet 定义的，但结果是 <代码>包含是IQueryable<T>.
The reason you are getting the error is because Find / FindAsync methods are defined for DbSet<T>, but the result of Include is IQueryable<T>.
另一种方法是将 FindAsync 与 显式加载:
Another way is to combine FindAsync with explicit loading:
model.Item = await db.Items.FindAsync(id);
if (model.Item == null)
{
return HttpNotFound();
}
await db.Entry(model.Item).Collection(i => i.ItemVerifications).LoadAsync();
这篇关于FindAsync 和 Include LINQ 语句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编程学习网！