RemoteAttribute not behaving as expected with null/empty data

Question

I want to validate user input using the [Remote] attribute. This is how this code looks in the model:

    [Remote(action:"VertifyPeriod",controller:"AllTasks")]
    public string Period { get; set; }

This is what the controller code looks like:

    [AcceptVerbs("GET", "POST")]
    public IActionResult VertifyPeriod(AllTask allTask)
    {            
        if (!string.IsNullOrEmpty(allTask.Period))
        {
                return Json(true);
        }
        return Json($"Wrong period value!");
        
    }

View code:

        <form asp-antiforgery="true" asp-action="Create">
        <div asp-validation-summary="ModelOnly" class="text-danger"></div>
        <div class="form-group">
            <label asp-for="Period" class="control-label"></label>
            <input type="text" asp-for="Period" class="form-control" />
            <span asp-validation-for="Period" class="text-danger"></span>
        </div>

If the user leaves the string empty the condition returns true, although it should return false It is listed as null in the database. I noticed peculiarity: If set a breakpoint on a conditional statement, it will never be reached. If I make another check condition, not related to checking for null then everything works fine. IsNullOrWhiteSpace doesn't work either. What could be the problem?

have you actually tried debugging the code? It's a pity that there is not any documentation about how the remote controller action should be implemented (what should it return). Usually it should return a bool value `true` or `false`. Really I don't understand why they think it's OK to not document anything about that. So I doubt that this `Json($"Wrong period value!")` actually means the same as `Json(true)`. You can just ***debug it*** to confirm it. — King King, Jan 31 '21 at 13:38
What were both the *value* and the `Length` of `allTask.Period` when you set a breakpoint on it and inspected it from the debugger? You *did* take a look at it, right? My guess is that it's some sort of unprintable characters.. Because I can assure you that `string.IsNullOrEmpty` and `string.IsNullOrWhiteSpace` both work absolutely 100% fine. — pinkfloydx33, Jan 31 '21 at 14:10
I tried debugging the code, value exactly null.But I noticed another peculiarity:If set a breakpoint on a conditional statement, it will never be reached. But if I change the conditional operator (for example, check for equality to a certain value), then the breakpoint is reached! — countneuroman, Jan 31 '21 at 15:06
Have you tried to modify the action to accept a string-type parameter `public IActionResult VertifyPeriod(string period)`? For more information about the `[Remote]` attribute, please check: https://learn.microsoft.com/en-us/aspnet/core/mvc/models/validation?view=aspnetcore-5.0#remote-attribute — Fei Han, Feb 01 '21 at 08:28
I've tried accept a string type parameter. Also does not work. — countneuroman, Feb 01 '21 at 12:16
`I noticed peculiarity: If set a breakpoint on a conditional statement, it will never be reached.` You can check this SO thread: https://stackoverflow.com/questions/14707460/remote-attribute-doesnt-trigger-when-field-is-blank — Fei Han, Feb 02 '21 at 08:26

RemoteAttribute not behaving as expected with null/empty data

0 Answers0