Please make EditForm always return its EditContext

[PeterHimschoot]

Describe the bug

When the EditForm component binds through the Model property, accessing the EditContext property returns null. Why not return the _fixedEditContext?

To Reproduce

I have a component with this EditForm:

<EditForm @ref="editForm"
          OnValidSubmit="@Submit"
          Model="@Customer">

In its @code I have this:

private EditForm editForm;

private bool isInvalid = false;

protected  override void OnInit()
{
    if( editForm?.EditContext == null)
  {
    Console.WriteLine("??? EditContext is null???");
  } else
  {
    isInvalid = editForm.EditContext.Validate();
  }

Expected behavior

I would expect that EditContext has a value, even though not set myself.

Additional context

This is on Blazor Preview 6

[mkArtakMSFT]

Thanks for contacting us, @PeterHimschoot. Feel free to send us a PR for this and we'll happily consider it.

[yasz]

Please enhance it

[neville-nazerane]

Is this about initializing the property EditForm to _fixedEditContext? Or will it make sense to ensure EditForm was never assigned?

I can't tell you why someone will, but what if someone assigns EditForm to null? Will it make sense for EditForm to return null after that point?

[Blackleones]

Are there any updates about this bug? Is it going to be fixed soon or we need to find a workaround?

[uabarahona]

I would like to take a look at this if nobody worked or is working on this yet

[uabarahona]

So the fix looks very easy but I would like to discuss more about it, basically we have:

We change the EditContext property to something like this

[Parameter] public EditContext EditContext 
{ 
    get{ return _customEditContext ??  _fixedEditContext; }  
    set { _customEditContext = value; } 
}

but we now loose the ability to know whether the EditContext was set explicitly or not, if that is a scenario we would have then, I think it will be better to have a new property FixedEditContext

Let me know your thoughts on this

[mwinkler]

I ran in this issue today, when I try to validate the from without a submit button. Please fix this.

[nunomaia]

I have created a new Property in my project to return the current EditContext. This allows me to force form validation without using a submit button. I unfortunately had to duplicate EditForm class in my project to overcome this.

public EditContext CurrentEditContext => _fixedEditContext

_fixedEditContext is already updated on OnParametersSet. .

// Update _fixedEditContext if we don't have one yet, or if they are supplying a
// potentially new EditContext, or if they are supplying a different Model

if (_fixedEditContext == null || EditContext != null || Model != _fixedEditContext.Model)
{
    _fixedEditContext = EditContext ?? new EditContext(Model);
}

[chrissainty]

@SteveSandersonMS Hi Steve, I would like to have a go at this one as part of the July sprint if that's ok?

In terms of the solution I've had a read through the comments and had a look through the code. The two proposed options so far are to make EditContext non-null and just return _fixedEditContext. However, this will break the functionality in OnParmaetersSet. The other option would be to add a new parameter to return _fixedEditContext.

As a third option, I thought we could add an additional field which would look something like:

private EditContext? _providedEditContext;

Then update the current EditContext parameter to look like this:

[Parameter]
public EditContext? EditContext
{
    get => _fixedEditContext;
    set => _providedEditContext = value;
}

The OnParametersSet method could then be updated to use the _providedEditContext field:

protected override void OnParametersSet()
{
    if ((_providedEditContext == null) == (Model == null))
    {
        throw new InvalidOperationException($"{nameof(EditForm)} requires a {nameof(Model)} " +
            $"parameter, or an {nameof(EditContext)} parameter, but not both.");
    }

    if (OnSubmit.HasDelegate && (OnValidSubmit.HasDelegate || OnInvalidSubmit.HasDelegate))
    {
        throw new InvalidOperationException($"When supplying an {nameof(OnSubmit)} parameter to " +
            $"{nameof(EditForm)}, do not also supply {nameof(OnValidSubmit)} or {nameof(OnInvalidSubmit)}.");
    }

    if (_fixedEditContext == null || _providedEditContext != null || Model != _fixedEditContext.Model)
    {
        _fixedEditContext = _providedEditContext ?? new EditContext(Model!);
    }
}

This would seem to give us everything we're after without breaking existing behavour in OnParametersSet, with the cost being an extra field. The user can always retrieve the current EditContext, even when it's created via the Model parameter. But we don't break the check for developers providing both EditContext and Model.

What do you think?

[SteveSandersonMS]

This sounds great, @chrissainty! Your design looks exactly optimal to me. Do you feel able to proceed with implementing this? Let me know if you think there are other outstanding questions.

[chrissainty]

Yep, already done :)

Are there any tests needed for this? I couldn't find any but I might have just missed them. I'll raise the PR but can add tests if needed.

[SteveSandersonMS]

Historically EditForm has only been tested via E2E tests since it was originally so trivial there wasn't really anything else to cover.

However it's now aggregating functionality so would justify adding a new unit test class in src\Components\Web\test\Forms. I wouldn't expect you to retrofit unit tests for other behaviors, but something covering the new ones would be good. And then we have a place to cover more stuff in the future too.

[captainsafia]

This is closed and will ship in RC1.