Form validation for Blazor (EditForm) to include validation error message for data annotations and custom validation at the same time

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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Can we please update the Blazor validation (EditForm) to include validation error message for both data annotations and custom validation at the same time. Currently the data annotation validation errors appear initially and when these are resolved, the custom validation errors show. It would be more user friendly for all validations to appear at the same time the editContext.Validate() is called. Here is an example form:

<EditForm EditContext="@editContext" OnSubmit="@HandleSubmit">
    <DataAnnotationsValidator />
    <div class="section">

<div class="row pb-3">
            <div class="offset-lg-3 col-lg-1">
                <label class="col-form-label">Code</label>
            </div>
            <div class="col-lg-4">
                <InputText class="form-control" @bind-Value="@TypeToAdd.Code" maxlength="15" />
                <ValidationMessage For="@(() => TypeToAdd.Code)" />
            </div>
        </div>
        <div class="row pb-3">
            <div class="offset-lg-3 col-lg-1">
                <label class="col-form-label">Name</label>
            </div>
            <div class="col-lg-4">
                <InputText class="form-control" @bind-Value="@TypeToAdd.Name" maxlength="100" />
                <ValidationMessage For="@(() => TypeToAdd.Name)" />
            </div>
        </div>
    </div>
    <button type="submit" autofocus class="button button-green"><span class="base-icon base-icon--save" style="background-color: white;"></span>Save</button>

</EditForm>

with the Model:

public class TypeModel : IValidatableObject
{
    public int TypeId { get; set; }
    [Required]
    public string Code { get; set; } = string. Empty;
    public string Name { get; set; } = string. Empty;
    public bool Active { get; set; }
    public DateTime ModifiedDateTime { get; set; }
    public bool IsPendingSync { get; set; }

public IEnumerable<ValidationResult> Validate(ValidationContext context)
    {
        var results = new List<ValidationResult>();

if (Name == null || Name == string. Empty)
        {
            results. Add(new ValidationResult("Name is required.", new[] { nameof(Name) }));
        }

return results;
    }
}
  

Here is the 'Handle Submit' method:

private async Task HandleSubmit()
{
    var isValid = editContext.Validate(); // 🔥 THIS is the key

if (!isValid)
        return;

await SaveUpdate();
}

If save is selected without entering any data into the InputText fields, the ‘Code’ field shows an error message but not ‘Name’. Once ‘Code’ has a value, then the ‘Name’ shows an error message.

I’m using .Net 10 and the latest Visual Studio 2026 Insiders [11709.129].

Thanks for considering.

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Original Comments

Feedback Bot on 4/21/2026, 00:57 AM:

Thank you for taking the time to provide your suggestion. We will do some preliminary checks to make sure we can proceed further. You will hear from us in about a week on our next steps.

[github-actions]

Triage Summary

Area: area-blazor — The issue is about Blazor's EditForm, DataAnnotationsValidator, and IValidatableObject custom validation behavior in Razor Components.

Type: Feature — The reporter is requesting a behavior change: they want data annotation errors and IValidatableObject custom validation errors to surface simultaneously. This is not a broken feature — it reflects the design of Validator.TryValidateObject, which only calls IValidatableObject.Validate() after all property-level ([Required], etc.) validations pass. The reporter is asking this behavior be changed in the Blazor DataAnnotationsValidator.

Notes

• The current behavior is consistent with how System.ComponentModel.DataAnnotations.Validator.TryValidateObject works: IValidatableObject.Validate() is only invoked when property-level data annotations have already passed. This is intentional at the framework level.
• This could be labeled by-design if the team decides the behavior correctly mirrors the underlying Validator semantics, or treated as a Feature if the team wants Blazor's validator to take a different approach (e.g., running both passes regardless and aggregating all errors).
• A workaround is to add a [Required] attribute to the Name property in addition to the IValidatableObject check, or to avoid relying on IValidatableObject for fields that are also required by data annotations.

Potential Duplicates

• None found — searches for similar issues did not return matching results.

Generated by Issue Triage Agent for dotnet/aspnetcore for issue #66966 · sonnet46 690K · ◷

[oroztocil]

Hi, thank you for contacting us!

Blazor forms with the DataAnnotationsValidator component validate their models either via System.ComponentModel.DataAnnotations.Validator or the newer Microsoft.Extensions.Validation (the latter is enabled by calling AddValidation during startup, for details see the docs). Both implementations have the same rules for validation execution ("short circuiting"):

1. First, properties of the model are validated (i.e. their validation attributes are executed).
2. If all properties are valid, type-level attributes of the model class are executed.
3. If no type-level errors were found and the type implements IValidatableObject, the IValidatableObject.Validate method is executed.
4. Finally, the collected errors are displayed.

The reason why the logic is set up like this is because this way the type level validations (class attributes and/or IValidatableObject implementation) can take for granted - when they actually run - that the individual properties are valid and do not need to re-check the invariants.

Depending on your use case, I would suggest either to write custom validation attributes used on individual properties (if the rule does not touch multiple properties or some other state), or to put the multi-step validation logic into the IValidatableObject.Validate method and return multiple errors as needed.

Let me know if this works for you.

[dotnet-policy-service]

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