Navigating the communication between a view component's form and a controller in ASP.NET Core

As a newcomer to web design using ASP.NET Core, I have created a view component that contains a form with various inputs related to a specific view model. One of these inputs happens to be a file input of the IFormFile datatype.

My goal is to submit this view model to a controller's POST action, validate the model's state, return another view component if the model is valid, and remain on the current view component with the same view model if the model is deemed invalid.

Here is the View Model I am working with: PricingViewModel.cs

public class PricingViewModel
{
    [Display(Name = "Select a file")]
    public IFormFile formFile { get; set; }

    [Display(Name = "ColumnCode")]
    [Required(ErrorMessage = "Enter {0} value, please")]
    public string colCode { get; set; }

    [Display(Name = "ColumnName")]
    [Required(ErrorMessage = "Enter {0} value, please")]         
    public string colName { get; set; }
}   

The View Component (controller) being used: PricingComponent.cs

public class PricingComponent : ViewComponent
{
    public async Task<IViewComponentResult> InvokeAsync(PricingViewModel pricing)
    {               
        return await Task.FromResult((IViewComponentResult)View("PricingView", pricing));
    }
}

The associated View Component (view): PricingView.cshtml

<form class="text-left" method="post" enctype="multipart/form-data">

   <input name="IsValidPricing" type="hidden" value="@ViewBag.isValid" />

   <div class="form-group text-left">
     <label asp-for="colCode" class="control-label"></label>
     <input asp-for="colCode" class="form-control" id="colCodeId"/>
     <span asp-validation-for="colCode" class="text-danger"></span>
   </div>

   <div class="form-group text-left">
     <label asp-for="colName" class="control-label"></label>
     <input asp-for="colName" class="form-control" id="colNameId"/>
     <span asp-validation-for="colName" class="text-danger"></span>
   </div>

   <div class="form-group text-left">
     <label asp-for="formFile" class="control-label"></label>
     <input type="file" accept=".xlsx, .csv" asp-for="formFile" id="MyInputFile"/>
   </div>

   <div class="form-group mt-4">
     <input type="submit" asp-action="ShowPricing" asp-controller="Home" value="Show" id="ShowPricingBtn" />
   </div>
</form>

The Home Controller in use: HomeController.cs

[HttpPost]
public IActionResult ShowPricing(PricingViewModel pricing)
{
    //Validation logic and handling of submission results
}

Plan A

The primary approach mentioned above.

Problem

Issues faced while trying to handle model validation and staying on the same view component.

Plan B

An alternate plan involving AJAX for better validation management.

Modifications made to PricingView.cshtml to accommodate AJAX behavior.

Problem

New problems encountered when implementing AJAX for model submission.

I need help deciding between the original or alternative approach. Can you identify where I might be going wrong?

Answer №1

Unsure of the terminology for view components? Check out these live demos:

PlanA:

1. Begin by creating

ViewComponents/PricingComponent.cs
and
ViewComponents/ShowPricingExcelComponent.cs
.

// PricingComponent
public class PricingComponent : ViewComponent
{
    public async Task<IViewComponentResult> InvokeAsync(PricingViewModel pricing)
    {
        return await Task.FromResult((IViewComponentResult)View("PricingView", pricing));
    }
}    
// ShowPricingExcelComponent
public class ShowPricingExcelComponent : ViewComponent
{
    public async Task<IViewComponentResult> InvokeAsync(PricingViewModel pricing)
    {
        return await Task.FromResult((IViewComponentResult)View("ShowPricingExcel", pricing));
    }
}

2. Next, create

Views/Shared/Components/PricingComponent/PricingView.cshtml
.

@model PricingViewModel 
// Form code here...

3. Create

Views/Shared/Components/ShowPricingExcelComponent/ShowPricingExcel.cshtml
.

<h1>Excel....</h1>

Project Structure:

https://i.sstatic.net/PfqbA.png

4. Add Views/Home/Index.cshtml:

@await Component.InvokeAsync("PricingComponent")

5. Update the HomeController:

// HomeController code here...

Result: https://i.sstatic.net/DLTX6.gif

For PlanB:

1. Start by creating

ViewComponents/PricingComponent.cs
and
ViewComponents/ShowPricingExcelComponent.cs
.

2. Then, create

Views/Shared/Components/PricingComponent/PricingView.cshtml
.

Detailed explanation...

@model PricingViewModel
// Form code with JavaScript logic...

3. Create

Views/Shared/Components/ShowPricingExcelComponent/ShowPricingExcel.cshtml
.

<h1>Excel....</h1>

4. Include Views/Home/Index.cshtml:

@await Component.InvokeAsync("PricingComponent")
<div id="ShowExcelTable"></div>

5. Adjust the HomeController as required:

// Updated HomeController logic...

Result: https://i.sstatic.net/FcGp6.gif

Answer №2

I tried to replicate the issue you mentioned, but everything seems to be working fine with your code. The validation message is appearing correctly.

In order to provide a fully functional demonstration, I included a GET method initially.

[HttpGet]
public IActionResult DisplayPrices() => ViewComponent("PricingComponent", new { pricing = new PricingViewModel() });

Access the following URL: Home/DisplayPrices

Complete the form accordingly.

https://i.sstatic.net/2TYzK.png

Submit the form. You should see the validation message displayed.

https://i.sstatic.net/lMn83.png

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