我不知道如何解决这个错误？计数 [英] I don't know how to solve this error ? count

问题描述

我有2个我喜欢的地方（其中）（和）

 其中 DB_A448D1_ilgswork.DueBy == DateTime。 Today.ToLongDateString（）
 其中 DB_A448D1_ilgswork.username == txtusername.Text 

我尝试过：

  var  getreminders =（ from  DB_A448D1_ilgswork  in  doAction.uni_projects 
 其中 DB_A448D1_ilgswork.DueBy == DateTime.Today.ToLongDateString（）
 其中 DB_A448D1_ilgswork.username == txtusername。文本
 选择 DB_A448D1_ilgswork）.ToList（）; 
 
  if （getreminders.Count >  =  1 ）
 {
 lbldue.Visible =  true ; 
 lbldue.Text =  你有 + getreminders.Count（）+  为今天设置的提醒; 
 lbnoldue.Visible =  false ; 
} 
  else  
 {
 lbnoldue.Visible =  true ; 
 lbldue.Visible =  false ; 
} 

解决方案

你没有说出什么样的错误。

I假设getreminders为null，因为你的查询没有给出结果。

当getreminders为null时，你无法访问Count属性。

你将得到一个空引用异常。



使用调试器看看你自己。



好​​的。红线在你的IDE中。

当然，IQueriable没有Count属性。

你应该把它转换成一个列表。

 var getreminders =（来自doAction.uni_projects中的DB_A448D1_ilgswork 
，其中DB_A448D1_ilgswork.DueBy == DateTime.Today.ToLongDateString（）
选择DB_A448D1_ilgswork） .ToList（）; 

i have 2 where what i loking for is to have (where) (and)

where DB_A448D1_ilgswork.DueBy == DateTime.Today.ToLongDateString() 
                                where DB_A448D1_ilgswork.username == txtusername.Text

What I have tried:

var getreminders = (from DB_A448D1_ilgswork in doAction.uni_projects
                                where DB_A448D1_ilgswork.DueBy == DateTime.Today.ToLongDateString() 
                                where DB_A448D1_ilgswork.username == txtusername.Text
                                select DB_A448D1_ilgswork).ToList();

            if (getreminders.Count >= 1)
            {
                lbldue.Visible = true;
                lbldue.Text = "You have " + getreminders.Count() + "reminders set for today";
                lbnoldue.Visible = false;
            }
            else
            {
                lbnoldue.Visible = true;
                lbldue.Visible = false;
            }

解决方案

You do not say what kind of error.
I assume that getreminders is null because your query gave no results.
You cannot access the Count property when getreminders is null.
You will get a null reference exception.

Use a debugger and see yourself.

OK. The red line is in your IDE.
Of course an IQueriable does not have a Count property.
You should convert it then to a list.

var getreminders = (from DB_A448D1_ilgswork in doAction.uni_projects
                              where DB_A448D1_ilgswork.DueBy == DateTime.Today.ToLongDateString()
                              select DB_A448D1_ilgswork).ToList();

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