i know this is a common problem, but none of the solutions resolved my issue. All explanations seemed logical at first but after implementing them it did absolutely nothing and im kinda at a loss here.

Nothing I do to lets me update my UI component and just display some error messages which come from DataAnnotation attributes. I am manually checking my data model for validity and in the case of being invalid I’m updating a list of error messages which in turn should be displayed inside my UI.

This is my component:

<GridEditSettings AllowAdding="true" AllowEditing="true" AllowDeleting="true" Mode="EditMode.Dialog"  Dialog="DialogParams" ShowConfirmDialog="true">
    <Validator>
        <DataAnnotationsValidator></DataAnnotationsValidator>
    </Validator>
    <Template>
        @{
            var unknownItem = (context as unknownasgdata);
            <div>
                @if (validationResults.Any())
                {
                    <div class="validation-summary">
                        @foreach (var validationResult in validationResults)
                        {
                            <div>@validationResult.ErrorMessage</div>
                        }
                    </div>
                }
                <br/>
                <div class="form-row">
                    <div class="form-group col-md-6">
                    <label><b>Bezeichnung</b></label><br />
                    @(unknownItem.description)
                    </div>

                </div>
                <div class="form-row">
                    <div class="form-group col-md-6">
                        <label><b>Betriebsstätte</b></label><br />
                        @(unknownItem.house)
                    </div>

                </div>
                <div class="form-row">
                    <div class="form-group col-md-6">
                        <label><b>Leistungsnummer</b></label><br />
                        @(unknownItem.leinr)
                    </div>
                </div>
                <div class="form-row">
                    <div class="form-group col-md-6">
                        <label><b>Preis</b></label><br />
                        <SfNumericTextBox @bind-Value="@(unknownItem.articleprice)" ></SfNumericTextBox>
                    </div>
                </div>
                <br/>
                <div class="form-row">
                    <div class="form-group col-md-6">
                    <label><b>Mahlzeitart</b></label><br/>
                    <SfDropDownList TValue="string" TItem="string" DataSource="@(new List<string> { "Frühstück", "Mittagessen", "Abendessen" })" @bind-Value="@(unknownItem.selectedMahlzeit)"></SfDropDownList>
                    </div> 
                </div>
            </div>
        }
    </Template>
    <FooterTemplate>
        <SfButton OnClick="@SubmitForm" IsPrimary="true">Speichern</SfButton>
        <SfButton OnClick="Cancel">Abbrechen</SfButton>
    </FooterTemplate>
</GridEditSettings>

@code{

    private async Task<bool> ValidateModel()
    {
        validationResults.Clear();
        bool isValid = Validator.TryValidateObject(unknownItem, validationContext, validationResults, true);
        Task.Delay(3000);
        return isValid;
    }

    private async Task SubmitForm()
    {
        if (await ValidateModel())
        {
            // Proceed with database updates
            // Your database update logic here

        }
        else
        {
            // Handle validation failures
            // Show validation messages
            validationResults = new List<ValidationResult>(validationResults);
            await Task.Delay(3000);
            await InvokeAsync(() =>
            {
                StateHasChanged(); // Ensure the UI is updated to reflect validation errors
            });
            await Task.Yield();
        }
    }

}

There is, of course, a bit of code missing here and there that is important to the class but you can just assume that the basics like initializing variables are working. What I am trying to do is just Submitting my Form and doing a Validation beforehand. ValidateModel() populates the List validationResults which I want to display in my razor component. In theory, shouldn’t the component re render as soon as I update the List, since I am checking for elements inside my razor components? I tried calling StateHasChanged multiple times sync and async and using Task.Delay whenever I can but nothing works and nothing lets me update the UI.