Warning '@(!isEditing || ...)' is not a valid value of attribute 'disabled'?

Question

(Tried both in Visaul Studio 2019 V16.4.0 or V16.4.1. Microsoft.CodeAnalysis.FxCopAnalyzers added)

I'm using the following code in Blazor to disable inputs.

<input type="checkbox" @bind="@v" disabled="@(!isEditing || ...expression omitted...)" />

However, Visual Studio warns that

Warning '@(!isEditing || ...)' is not a valid value of attribute 'disabled'

What's the proper way to disable the input by custom logic?

What version of Visual Studio are you running? I just tried your code and do not get a warning. — Kyle, Commented Dec 12, 2019 at 22:06
Visual studio 2019 with code cop package and another extension which checks code installed. — ca9163d9, Commented Dec 13, 2019 at 3:39
What is ...omitted... ?? Post the actual code or create a minimal reproducible example — Henk Holterman, Commented Dec 13, 2019 at 10:08
@ca9163d9 Is your VS 2019 up to date? I'm on 16.4.1 and do not have this problem. — Kyle, Commented Dec 13, 2019 at 18:49

ca9163d9 · Accepted Answer · 2019-12-26 21:42:12Z

2

It's a bug.

HTML warning when setting disabled attribute using Razor syntax #16833 https://github.com/aspnet/AspNetCore/issues/16833

Update:

All the warnings are disappeared after my Visual Studio is upgraded to V16.4.2.

answered Dec 24, 2019 at 16:25

ca9163d9

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Hmmm that issue is still open and it is specifically stated that the () in @(...) solve it. There probably is another issue overthere that ic closer.
– Henk Holterman
Commented Dec 24, 2019 at 20:23
2

In vs2022 I received the same warning -
– Sith2021
Commented Oct 5, 2021 at 16:25

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agua from mars · Accepted Answer · 2019-12-12 22:37:21Z

0

html disabled attribute acceptable value is disabled or no value.
The easiest way is to use an @if statement:

@if(!isEditing || ...omitted...)
{
   <input type="checkbox" @bind="@v" disabled />
}
else
{
   <input type="checkbox" @bind="@v" />
}

answered Dec 12, 2019 at 22:37

agua from mars

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1

Blazor should make this unnecessary.
– Henk Holterman
Commented Dec 13, 2019 at 16:58
If you pass in a false value in Blazor, it will omit the disabled attribute. This answer is misleading.
– Kyle
Commented Dec 13, 2019 at 17:14
@Kyle, Actualy, you're right, but the compiler warns. The issue is how to avoid compilation warnings.
– agua from mars
Commented Dec 13, 2019 at 18:44
1

There should be no compilation warning either, I tried it on visual studio 16.4.1 and do not have the issue.
– Kyle
Commented Dec 13, 2019 at 18:48

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John · Accepted Answer · 2019-12-13 15:53:44Z

0

Use a ternary expression:

<input type="checkbox" @bind="@v" @((!isEditing || ...expression omitted...) ? "disabled" : "") />

answered Dec 13, 2019 at 15:37

John

5794 silver badges20 bronze badges

Will this generate disabled=disabled or disabled=?
– ca9163d9
Commented Dec 13, 2019 at 15:40
1

@John, not correct... If the expression is evaluated to true, then the attribute disabled is present, else it is missing. The disabled attribute is never assigned a value in HTML. It is either missing or present.
– enet
Commented Dec 13, 2019 at 15:50
@enet you're right, thanks for pointing that out. I remember some frameworks allow you to do it that way, but seems it doesn't work that way with plain html. I've updated my answer.
– John
Commented Dec 13, 2019 at 15:55

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3 Answers 3