InvalidOperationException: EditForm requires a Model parameter, or an EditContext parameter, but not both.

[donhuvy]

I am using .NET Core 3.0.100 , Blazor Server web-app, Microsoft Visual Studio 2019 Community Preview.

I follow this guide https://docs.microsoft.com/en-us/aspnet/core/blazor/forms-validation?view=aspnetcore-3.0

File ExampleModel.cs

using System.ComponentModel.DataAnnotations;

namespace acc133blazor.Models
{

    public class ExampleModel
    {
        [Required]
        [StringLength(10, ErrorMessage = "Name is too long.")]
        public string Name { get; set; } 
    }

}

and file Foo.razor

@page "/foo"
@using acc133blazor.Models;

<EditForm Model="@exampleModel" OnInvalidSubmit="@HandleValidSubmit">
    <DataAnnotationsValidator />
    <ValidationSummary />
    <InputText id="name" @bind-Value="@exampleModel.Name" />
    <button type="submit">Submit</button>
</EditForm>

@code {
    private ExampleModel exampleModel { get; set; }

    private void HandleValidSubmit()
    {
        Console.WriteLine("OnValidSubmit");
    }
}

I go to https://localhost:44333/foo

error

InvalidOperationException: EditForm requires a Model parameter, or an EditContext parameter, but not both.
Microsoft.AspNetCore.Components.Forms.EditForm.OnParametersSet()
Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()
Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)
Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)
Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewComponentFrame(ref DiffContext diffContext, int frameIndex)
Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewSubtree(ref DiffContext diffContext, int frameIndex)
Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InsertNewFrame(ref DiffContext diffContext, int newFrameIndex)
Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(ref DiffContext diffContext, int oldStartIndex, int oldEndIndexExcl, int newStartIndex, int newEndIndexExcl)
Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, int componentId, ArrayRange<RenderTreeFrame> oldTree, ArrayRange<RenderTreeFrame> newTree)
Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)
Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessPendingRender()
Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(int componentId, RenderFragment renderFragment)
Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()
Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()
Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)
Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)
Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderRootComponentAsync(int componentId, ParameterView initialParameters)
Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.CreateInitialRenderAsync(Type componentType, ParameterView initialParameters)
Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters)
Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext+<>c__11<TResult>+<<InvokeAsync>b__11_0>d.MoveNext()
Microsoft.AspNetCore.Mvc.ViewFeatures.RazorComponents.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)
Microsoft.AspNetCore.Mvc.Rendering.HtmlHelperComponentExtensions.PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)
Microsoft.AspNetCore.Mvc.Rendering.HtmlHelperComponentExtensions.RenderComponentAsync<TComponent>(IHtmlHelper htmlHelper, RenderMode renderMode, object parameters)
acc133blazor.Pages.Pages__Host.<ExecuteAsync>b__8_1() in _Host.cshtml
+
        @(await Html.RenderComponentAsync<App>(RenderMode.ServerPrerendered))
Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync()
acc133blazor.Pages.Pages__Host.ExecuteAsync()
Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, bool invokeViewStarts)
Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, string contentType, Nullable<int> statusCode)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|29_0<TFilter, TFilterAsync>(ResourceInvoker invoker, Task lastTask, State next, Scope scope, object state, bool isCompleted)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext<TFilter, TFilterAsync>(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, object state, bool isCompleted)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.MigrationsEndPointMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Raw exception detail

System.InvalidOperationException: EditForm requires a Model parameter, or an EditContext parameter, but not both.
   at Microsoft.AspNetCore.Components.Forms.EditForm.OnParametersSet()
   at Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
   at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewComponentFrame(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewSubtree(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InsertNewFrame(DiffContext& diffContext, Int32 newFrameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, Int32 componentId, ArrayRange`1 oldTree, ArrayRange`1 newTree)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessPendingRender()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(Int32 componentId, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()
   at Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
   at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderRootComponentAsync(Int32 componentId, ParameterView initialParameters)
   at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.CreateInitialRenderAsync(Type componentType, ParameterView initialParameters)
   at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters)
   at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.<>c__11`1.<<InvokeAsync>b__11_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.ViewFeatures.RazorComponents.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)
   at Microsoft.AspNetCore.Mvc.Rendering.HtmlHelperComponentExtensions.PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)
   at Microsoft.AspNetCore.Mvc.Rendering.HtmlHelperComponentExtensions.RenderComponentAsync[TComponent](IHtmlHelper htmlHelper, RenderMode renderMode, Object parameters)
   at acc133blazor.Pages.Pages__Host.<ExecuteAsync>b__8_1() in C:\Users\donhuvy\Desktop\acc133b3\acc133blazor\Pages\_Host.cshtml:line 38
   at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync()
   at acc133blazor.Pages.Pages__Host.ExecuteAsync()
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|29_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.MigrationsEndPointMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Maybe related to this content dotnet/aspnetcore#11331 (comment)

---

Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

• ID: eef47457-c8cf-74a4-b884-c1fe5c2ef52d
• Version Independent ID: 09a02d10-2834-467d-d8c2-3fd19ceb3863
• Content: ASP.NET Core Blazor forms and validation
• Content Source: aspnetcore/blazor/forms-validation.md
• Product: aspnet-core
• Technology: aspnetcore-blazor
• GitHub Login: @guardrex
• Microsoft Alias: riande

[guardrex]

You didn't create an instance of ExampleModel for your exampleModel.

private ExampleModel exampleModel { get; set; } = new ExampleModel();

... or assign it to exampleModel on OnInitializedAsync.

[f135ta]

@guardrex - What a really obscure exception message.. Thanks!

[guardrex]

Wow ..... yeah ... that number of 👍 means that devs are hitting this one BIG TIME.

It needs special attention in the topic to avoid more 🤕 pain 🤕.

[khayol]

The same issue!

Who can help me?

This Delete Page working well, but if for testing I want to delete the not existing row Id, I got the same issue

@page "/IndOrg/ContactDelete/{CurrentID}"
@Inject ContactController objContactController

<AuthorizeView Roles="@admSer.GetRolesList("ContactDelete")" Context="authContext" >

<WrPnlElm>
    <ControlQuickAccess>
            <input type="submit" class="btn bnt-style-general"  value="@trs.GetTranslation("Delete",@AppData.ActiveUser,"General")">
            <input   type="button" class="btn btn bnt-style-general" @onclick="@Cancel" value="@trs.GetTranslation("Cancel",@AppData.ActiveUser,"General")">
    </ControlQuickAccess>
</WrPnlElm>

<WrFormBody>
    <FormElements>
        <h4>@trs.GetTranslation("AreYouSureToDeteteRow",@AppData.ActiveUser,"General")</h4>

         <WrFieldInt TransEntity="Individual" FieldCaption="Code" 
        ReadonlyOpt="readonlyMain1" Val="@objContact.Code" />

        <WrFieldStr ReadonlyThis="readonlyMain1" FieldCaption="Name"
        TransEntity="Individual"  @bind-BindingValue ="@objContact.Name"/> 

  </FormElements>      
</WrFormBody>    
</EditForm>    

@code{
[Parameter]
public string CurrentID {get;set;}
Contact objContact= new Contact();
private bool readonlyMain1 {get;set;}=false;

   protected override void OnInitialized()
{
  readonlyMain1=AppData.readonlyMain1;
  objContact = objContactController.GetContactById(Convert.ToInt32(CurrentID));       
}

protected void DeleteContact(){

    objContactController.DeleteContact(objContact);
    NavManager.NavigateTo("/IndOrg/ContactViewStd/"+AppData.Individual_IdSelect);
}
void Cancel(){
    NavManager.NavigateTo("/IndOrg/ContactViewStd/"+AppData.Individual_IdSelect);
}

}

[guardrex]

@khayol ... We don't have the staffing to provide product support. Open your question on one or more of the open dev support forums out there, such as ...

• Stack Overflow (tag: blazor)
• ASP.NET Core Slack Team
• Blazor Gitter

[hubsamirus]

var model = new BlazorTable();

    var cut = RenderComponent<EditForm>(parameters => parameters.Add(p => p.Model, model));