Bool 问题 - 改变值

发布于 2024-09-25 16:16:21 字数 840 浏览 6 评论 0原文

大家早上好。

我使用以下方法来尝试返回布尔值：

public static bool GetShowCatSubProdStatus(string memberid, string username)
    {
        MyEnts showcatsubprodstatus = new MyEnts.PDC_VDSOREntities35();

        var r = from p in showcatsubprodstatus.tblKeyAccountInfoes
                where p.MemberID == memberid && p.UserName == username
                select p.ShowCatSubProd;

        return r.Any();
    }

当我调用此方法并调试它时，结果是正确的。但是，当我在页面加载中运行此方法时，尽管方法结果返回正确的结果，但当我单步执行时，布尔值会发生变化！

 bool showcatsubprodstatus = MyEnts.GetShowCatSubProdStatus(_memberid, _username);

        if (showcatsubprodstatus != true)
        {
            panCatSubProd.Visible = false;
        }

有人可以解释一下这里发生了什么以及我如何解决这个难题吗？！

PS：抱歉太厚了。

编辑 - 正确，将其范围缩小到变量。无论方法结果如何，它总是返回“true”？！？！

原文

Morning all.

I have the following method that I use to to try and bring back a bool:

public static bool GetShowCatSubProdStatus(string memberid, string username)
    {
        MyEnts showcatsubprodstatus = new MyEnts.PDC_VDSOREntities35();

        var r = from p in showcatsubprodstatus.tblKeyAccountInfoes
                where p.MemberID == memberid && p.UserName == username
                select p.ShowCatSubProd;

        return r.Any();
    }

When I call this method and debug it, the result is correct. However, when I run this method in a page load, although the method result returns the correct result, when I step through, the boolean value changes!

 bool showcatsubprodstatus = MyEnts.GetShowCatSubProdStatus(_memberid, _username);

        if (showcatsubprodstatus != true)
        {
            panCatSubProd.Visible = false;
        }

Can someone explain what is going on here and how I can solve this puzzler?!

PS: Apologies for being thick.

EDIT - Right, narrowed it down to the variable. It is always return 'true' regardless of the method result?!?!

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夏末 2024-10-02 16:16:21

这段代码返回一个 IEnumerable ：

var r = from p in showcatsubprodstatus.tblKeyAccountInfoes
        where p.MemberID == memberid && p.UserName == username
        select p.ShowCatSubProd;

通过调用 .Any()，您可以询问 IEnumerable 中是否有任何项目。如果有则返回 true；

这就是为什么你总是得到真实的回报，因为它总能找到一些东西。

解决方案
要么调用 .SingleOrDefault() 返回唯一的元素（如果有），要么返回该类型的默认值。

var r = from p in showcatsubprodstatus.tblKeyAccountInfoes
        where p.MemberID == memberid && p.UserName == username
        select p.ShowCatSubProd;
return r.SingleOrDefault(); //assuming p.ShowCatSubProd is a bool and not a Nullable<bool> else you need to adjust your return type or cast it to a boolean using .GetValueOrDefault().

This piece of code returns an IEnumerable<bool> :

var r = from p in showcatsubprodstatus.tblKeyAccountInfoes
        where p.MemberID == memberid && p.UserName == username
        select p.ShowCatSubProd;

By calling the .Any() you are asking it if there are any items in the IEnumerable. If there are you return true;

That is why you always get true back, because it always finds something.

The solution
Either you go for calling .SingleOrDefault() which returns the only element there is (if there is one) or returns the default value of that type.

var r = from p in showcatsubprodstatus.tblKeyAccountInfoes
        where p.MemberID == memberid && p.UserName == username
        select p.ShowCatSubProd;
return r.SingleOrDefault(); //assuming p.ShowCatSubProd is a bool and not a Nullable<bool> else you need to adjust your return type or cast it to a boolean using .GetValueOrDefault().

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