CODEWITHSUNDEEP
.net-coremodel-bindingrazor-pages
Rob Bowman
Rob Bowman

Reputation: 8711

Razor Pages - Returning Model Value

I'm new to Razor pages and having trouble with model binding back to the view.

I'm using VS2019 version 16.0.4.

This is my PageModel:

public class IndexModel : PageModel
{
    [BindProperty]
    public int PageIndex { get; set; }

    public IActionResult OnPost()
    {
        PageIndex++;
        return Page();
    }
}

And my View:

@page
@model IndexModel

<form method="post">
    <div class="form-group">
        <label asp-for="PageIndex"></label>
        <input asp-for="PageIndex" class="form-control" />
        <span class="text-danger" asp-validation-for="PageIndex"></span>

        <button type="submit" class="btn btn-primary">Increment</button>
    </div>
</form>

I would expect the value displayed in the input control to be incremented on each click - but it remains at zero. The binding into the controller seems to work ok. If I enter a value of "5" and click the button then a breakpoint shows me that a value of 5 is received before being incremented to 6. However, the incremented value does not get reflected back to the view.

Where did I go wrong?

Upvotes: 0

Views: 1516

Answers (1)

Mike Brind
Mike Brind

Reputation: 30045

Model binding takes values from the HTTP request and binds them to handler method parameters or PageModel properties. It is not two-way, and does not then bind those values back to the controls where the values originated.

You need to explicitly set the value attribute of the input to see the behaviour that you expect:

<input asp-for="PageIndex" value="@Model.PageIndex" />

Upvotes: 1

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