如何以编程方式设置标签文本 - Linq To Entities

发布于 2024-09-14 05:36:30 字数 816 浏览 1 评论 0原文

我必须根据用户偏好在网页上设置大量不同标签的标签文本。

我在标签加载事件上放置了以下代码（可能是错误的！）

string memberid = Session["MemberID"].ToString();
            string locationid = Session["LocationID"].ToString();
            string userName = Membership.GetUser().UserName;
            string uuf1 = "UnitUserField1";

            MyEntities lblUUF1Text = new MyEntities();

            lblUUF1.Text = lblUUF1Text.tblUserPreferences
                            .Where(p => p.MemberID == memberid && p.LocationID == locationid && p.Username == userName && p.ColumnName == uuf1)
                            .Select(p => p.Alias)
                            .ToString();

但是，当我运行此代码时，返回的标签文本是：

System.Data.Objects.ObjectQuery`1[System.String]

有人可以在我的方法错误。我现在感觉非常非常厚重。

原文

I have to set the label text of a load of differnet labels on a web page based upon user preferences.

I have the following code that is place upon the label load event (probably wrong!)

string memberid = Session["MemberID"].ToString();
            string locationid = Session["LocationID"].ToString();
            string userName = Membership.GetUser().UserName;
            string uuf1 = "UnitUserField1";

            MyEntities lblUUF1Text = new MyEntities();

            lblUUF1.Text = lblUUF1Text.tblUserPreferences
                            .Where(p => p.MemberID == memberid && p.LocationID == locationid && p.Username == userName && p.ColumnName == uuf1)
                            .Select(p => p.Alias)
                            .ToString();

However when I run this, the label text returned is:

System.Data.Objects.ObjectQuery`1[System.String]

Can someone point me in the error of my ways. I'm feeling very, very thick at the moment.

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堇色安年 2024-09-21 05:36:30

您正在编写一个查询，然后要求将该查询转换为字符串。您只想要该查询的第一个结果吗？如果是这样，那就很简单了：（

lblUUF1.Text = lblUUF1Text.tblUserPreferences
                          .Where(p => p.MemberID == memberid && 
                                 p.LocationID == locationid && 
                                 p.Username == userName && p.ColumnName == uuf1)
                        .Select(p => p.Alias)
                        .First();

我假设 p.Alias 的类型已经是 string，但是您包含了对 ToString 的调用> 作为尝试将查询强制转换为字符串以使其编译。）

请注意，如果没有结果，则会出现异常。否则它将采用第一个结果。其他选项包括：

确定只有一个结果吗？使用 Single()
你认为是零还是一？使用 SingleOrDefault()，存储在局部变量中，如果结果不为 null，则设置标签文本。
认为有从零到多的东西吗？以同样的方式使用 FirstOrDefault()。

You're writing a query and then asking that query to be converted to a string. Do you only want the first result of that query? If so, it's easy:

lblUUF1.Text = lblUUF1Text.tblUserPreferences
                          .Where(p => p.MemberID == memberid && 
                                 p.LocationID == locationid && 
                                 p.Username == userName && p.ColumnName == uuf1)
                        .Select(p => p.Alias)
                        .First();

(I'm assuming that the type of p.Alias is already string, but that you included the call to ToString as an attempt to coerce the query into a string to make it compile.)

Note that if there are no results, that will blow up with an exception. Otherwise it'll take the first result. Other options are:

Sure there's exactly one result? Use Single()
Think there's either zero or one? Use SingleOrDefault(), store in a local variable and set the label text if the result isn't null.
Think there's anything from zero to many? Use FirstOrDefault() in the same way.

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日久见人心 2024-09-21 05:36:30

你需要一个 .First() 在那里

lblUUF1.Text = lblUUF1Text.tblUserPreferences
                            .Where(p => p.MemberID == memberid && p.LocationID == locationid && p.Username == userName && p.ColumnName == uuf1)
                            .Select(p => p.Alias).First().ToString();

You need a .First() in there

lblUUF1.Text = lblUUF1Text.tblUserPreferences
                            .Where(p => p.MemberID == memberid && p.LocationID == locationid && p.Username == userName && p.ColumnName == uuf1)
                            .Select(p => p.Alias).First().ToString();

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神妖 2024-09-21 05:36:30

ToString() 将返回您所看到的对象类型，您需要做的是：

lblUUF1.Text = lblUUF1Text.tblUserPreferences
                .Where(p => p.MemberID == memberid && p.LocationID == locationid && p.Username == userName && p.ColumnName == uuf1)
                .Select(p => p.Alias).SingleOrDefault();

ToString() will return the object type as you see, what you will need to do is this:

lblUUF1.Text = lblUUF1Text.tblUserPreferences
                .Where(p => p.MemberID == memberid && p.LocationID == locationid && p.Username == userName && p.ColumnName == uuf1)
                .Select(p => p.Alias).SingleOrDefault();

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