Dynamically change error message from controllerRSS

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  bank5

  Member

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  317 Posts

  Dynamically change error message from controller

  Oct 14, 2019 05:49 PM|bank5|LINK

  I'm trying to validate documents the using the following:

  ViewModel:

  [Remote("IsValidDocument", "Home", HttpMethod = "POST")]
  public IFormFile Doc1 { get; set; }
  
  [Remote("IsValidDocument", "Home", HttpMethod = "POST")]
  public IFormFile Doc2 { get; set; }

  View:
  
  <label asp-for="Doc1" class="control-label"></label>
                  <input asp-for="Doc1" type="file" class="form-control" />
                  <span asp-validation-for="Doc1" class="text-danger"></span>
  
  <label asp-for="Doc2" class="control-label"></label>
                  <input asp-for="Doc2" type="file" class="form-control" />
                  <span asp-validation-for="Doc2" class="text-danger"></span>

  
  Home Controller:

  [HttpPost]
          public JsonResult IsValidDocument (object value)
          {
              int MaxContentLength = 1024 * 1024 * 10; //Max 10 MB file
              string[] AllowedFileExtensions = new
              string[] { ".doc", ".docx", ".odf", ".pdf", ".rtf", ".txt" };
  
              var file = value as IFormFile;
              if (!AllowedFileExtensions.Contains((file != null) ?
                      file.FileName.Substring(file.FileName.LastIndexOf('.')).ToLower() :
                      string.Empty))
              {
                  ModelState.AddModelError(value.ToString(), "Please upload a document of type: " + string.Join(", ", AllowedFileExtensions));
                  
                  return Json(false);
              }
              else if (file.Length > MaxContentLength)
              {
                  ModelState.AddModelError(value.ToString(), "Your document is too large, maximum allowed size is : " + (MaxContentLength / 1024).ToString() + "MB";);
                  return Json(false);
              }
              else
                  return Json(true);
  
          }

  However, ModelState.AddModelError is not outputting the error message.  I'm pretty sure it's because the key parameter is off.  What can I do to show the proper error messages?
  
  

• • Reply
  ryanbesko

  Contributor

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  Re: Dynamically change error message from controller

  Oct 14, 2019 08:25 PM|ryanbesko|LINK

  Do you have @Html.ValidationSummary() on your page?

  Mark all posts that give the desired result the answer. If you only mark the last that gave you clarification because you misread an earlier post others will be confused. Some of us are here to help others and our point to post ratio matters.
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  DA924

  Contributor

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  3315 Posts

  Re: Dynamically change error message from controller

  Oct 14, 2019 08:32 PM|DA924|LINK

  I believe you would have to use the ValidationSummary in the view to show any error messages that were set by you manually setting error messages using ModelState.AddModelError() in the error collection.  What are you doing if the ModelState is valid? Are you checking for the Modelstate being valid, becuase if so, it will remain invalid until you remove all messages you have placed into the error message collection used by ModelState logic?

  @using (Html.BeginForm())
  {
      @Html.ValidationSummary(false, "", new { @class = "text-danger" })
  
  <fieldset>
  
      <legend>Create</legend>

  If you find the post has answered your issue, then please mark post as 'answered'.
• • Reply
  bank5

  Member

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  317 Posts

  Re: Dynamically change error message from controller

  Oct 15, 2019 12:37 AM|bank5|LINK

  Thanks for the replies.  I was having problems with the JsonResult script so I wound up creating a Validation Attribute instead.  I haven't tested extensively, but this seems to be working for the most part and is easy to return different error messages.

  using System;
  using System.Linq;
  using Microsoft.AspNetCore.Http;
  using System.ComponentModel.DataAnnotations;
  
  namespace Cwec.Attributes
  {
      public class ValidateDocumentAttribute : ValidationAttribute
      {
          public override bool IsValid(object value)
          {
  
              int maxContentLength = 1024 * 1024 * 10; //Max 10 MB file
              string[] allowedFileExtensions = new string[] { ".doc", ".docx", ".odf", ".pdf", ".rtf", ".txt" };
                  
              var file = value as IFormFile;
  
              if (file == null)
                  return true;
              else if (!allowedFileExtensions.Contains(file.FileName.Substring(file.FileName.LastIndexOf('.')).ToLower()))
              {
                  ErrorMessage = "Please upload a document of type: " + string.Join(", ", allowedFileExtensions);
                  return false;
              }
              else if (file.Length > maxContentLength)
              {
                  ErrorMessage = "Your document is too large, maximum allowed size is : " + (maxContentLength / 1024).ToString() + "MB";
                  return false;
              }
  
              else
                  return true;
              
          }
      }
  }

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  yogyogi

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  Re: Dynamically change error message from controller

  Oct 15, 2019 05:49 AM|yogyogi|LINK

  Dynamically change error message from controller - In order to do this I suggest you to use Custom Model Validation Attribute in your application.

  Helping you always. Don't forget to click "Mark as Answer" on the post that helped you.
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