Blazor generated onclick events on loop do not work

[huto1]

the bellow one works perfectly.

<p><button onclick="@(new Action(() => tstmethod("tt")))">test method</button></p>

And this one does not work, which is a big issue. If this does not work, there is no way to do any kind of list output.

        @for (int i = 0; i < 5; i++)
        {
            <p><button onclick="@(new Action(() => tstmethod(i.ToString())))">test method</button></p>
        }

method being used:

void tstmethod(string tst1)
    {
        tst = tst1;
    }

Is there any way to accomplish this? Or will it only be fixed in the next version?

[vertonghenb]

You're not using the correct syntax, mind the "@" sign before onclick:

<p><button @onclick="@(_ => tstmethod("tt"))">test method</button></p>

or

        @for (int i = 0; i < 5; i++)
        {
            <p><button @onclick="@(new Action(() => tstmethod(i.ToString())))">test method</button></p>
        }

[campersau]

In addition to @vertonghenb comment you also need to capture the variable inside the loop.

The necessity to declare a variable inside your loop is just how C# lambdas work - they bind to a variable, not to the value that was in the variable when the lambda was constructed.

https://github.com/aspnet/Blazor/issues/275#issuecomment-373686979

This is documented here: https://docs.microsoft.com/en-us/aspnet/core/blazor/components?view=aspnetcore-3.0#lambda-expressions

Other issues:
#12235
#10327
#10138
#7134
https://github.com/aspnet/Blazor/issues/1562
https://github.com/aspnet/Blazor/issues/1402
https://github.com/aspnet/Blazor/issues/1422
https://github.com/aspnet/Blazor/issues/764
https://github.com/aspnet/Blazor/issues/447
https://github.com/aspnet/Blazor/issues/275

[huto1]

@vertonghenb your solution solved the problem. @vertonghenb yes, we do need to assign the loop value to another variable:

 @for (int i = 0; i < 5; i++)
        {
            var a = i;
            <p><button @onclick="@(new Action(() => tstmethod(a.ToString())))">test method</button></p>
        }

There was probably some change in the later version, it would be useful if the at sign had some additional coloring to it.

[vertonghenb]

@huto1 there is a coloring see the following test:

[huto1]

@vertonghenb It used to be green like that, but not anymore.