morry329# Posts - Answer Overflow

morry329#

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CC#

•Created by morry329# on 3/30/2025 in #help

Cannot return null from an action method with a return type of 'Microsoft.AspNetCore.Mvc.JsonResult'

8 replies

CC#

•Created by morry329# on 3/23/2025 in #help

asp-net notation does not recognise attribute notation from a model class

My Rider flagged this ListingImage notation as unrecognisable in cshtml

<form enctype="multipart/form-data" >
        <div class="custom-file">
            <input asp-for="ListingImage" type="file" class="custom-file-input fileUpload" /> /*Rider does not recognise ListingImage*/ 
            <label class="custom-file-label fileLabel">Choose file</label>
        </div>
        <input type="submit" value="Submit" />
    </form>

<form enctype="multipart/form-data" >
        <div class="custom-file">
            <input asp-for="ListingImage" type="file" class="custom-file-input fileUpload" /> /*Rider does not recognise ListingImage*/ 
            <label class="custom-file-label fileLabel">Choose file</label>
        </div>
        <input type="submit" value="Submit" />
    </form>

This ListingImage came from this model class

public class ListingProjects_ver2
{
    
    [System.ComponentModel.DataAnnotations.Key]
    [Required]
    public int? Id { get; set; } 

    [Required]
    public string? ListingName { get; set; }

    [NotMapped]
    [Display(Name = "ListingImage")]
    [DataType(DataType.Upload)]
    public IFormFile? ListingImage { get; set; } /*This one has linked to my cshtml*/
    
    public string? ListingImageFilePath { get; set; }
}

public class ListingProjects_ver2
{
    
    [System.ComponentModel.DataAnnotations.Key]
    [Required]
    public int? Id { get; set; } 

    [Required]
    public string? ListingName { get; set; }

    [NotMapped]
    [Display(Name = "ListingImage")]
    [DataType(DataType.Upload)]
    public IFormFile? ListingImage { get; set; } /*This one has linked to my cshtml*/
    
    public string? ListingImageFilePath { get; set; }
}

I think this error is a beginner's mistake, I miss out something. But I need your help to find out why my cshtml does not recognise ListingImage from the model class. Could anyone point me in the right direction? For your reference my full code https://paste.mod.gg/aplkygbhtnqj/0

8 replies

CC#

•Created by morry329# on 3/21/2025 in #help

✅ Rider does not recognise WebImage Helper

I have a simple crud app. I would like to add a drop-down menu and button like this tutorial https://learn.microsoft.com/en-us/aspnet/web-pages/overview/ui-layouts-and-themes/9-working-with-images I just copied and pasted this tutorial code into my source code on Rider @{
WebImage photo = null; var newFileName = ""; var imagePath = ""; var imageThumbPath = ""; if(IsPost){ photo = WebImage.GetImageFromRequest(); if(photo != null){ newFileName = Guid.NewGuid().ToString() + "_" + Path.GetFileName(photo.FileName); imagePath = @"images" + newFileName; photo.Save(@"~" + imagePath); imageThumbPath = @"images\thumbs" + newFileName; photo.Resize(width: 60, height: 60, preserveAspectRatio: true, preventEnlarge: true); photo.Save(@"~" + imageThumbPath); } } } However Rider flags WebImage Helper as non-reconizable symbol. My abysmal Google search does not tell me what to do. No idea which NuGet Package/dependencies is missing on my Rider. Could anyone kindly point me in the right direction? Is there an alternative to WebImage Helper which just lets my code add the image drop-down button? My Rider does not have the UI overview that lets me add it per drag and drop, just to let you know.

8 replies

CC#

•Created by morry329# on 3/15/2025 in #help

✅ the type or namespace name 'ListingProjects' does not exist in the namespace models

32 replies

CC#

•Created by morry329# on 2/13/2025 in #help

Id points to always null

I have an Edit method which always returns a null id: https://pastecode.io/s/upokmghg I tried to map the Id (from the controller/model) on my cshtml but it did not help. Could anyone kindly point me in the right direction??

7 replies

CC#

•Created by morry329# on 2/8/2025 in #help

The edit method does not edit the pre-existing data but it creates a new data entry with NULL

26 replies

CC#

•Created by morry329# on 2/6/2025 in #help

InvalidCastException: Unable to cast object of type

The full exception reads

InvalidCastException: Unable to cast object of type 'Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable1[WebApplication1.Models.ListingProjectsDTO]' to type 'System.String'.

The exception points at this method

public async Task<IActionResult> TestDashboard1()
    {
        var datasource = _context.ListingDTO_DBTable.AsQueryable();
        var query = datasource
            .Select(x => new ListingProjectsDTO() {
                Id = x.Id,
                ListingName = x.ListingName,
            });
         ConvertFromDBVal<string>(query);
        var listings = await query.ToListAsync();
        
        
        return View(listings);
    }
    
    public static T ConvertFromDBVal<T>(object obj)
    {
        if (obj == null || obj == DBNull.Value)
        {
            return default(T); 
        }
        else
        {
            return (T)obj; //InvalidCastException
        }
    }

public async Task<IActionResult> TestDashboard1()
    {
        var datasource = _context.ListingDTO_DBTable.AsQueryable();
        var query = datasource
            .Select(x => new ListingProjectsDTO() {
                Id = x.Id,
                ListingName = x.ListingName,
            });
         ConvertFromDBVal<string>(query);
        var listings = await query.ToListAsync();
        
        
        return View(listings);
    }
    
    public static T ConvertFromDBVal<T>(object obj)
    {
        if (obj == null || obj == DBNull.Value)
        {
            return default(T); 
        }
        else
        {
            return (T)obj; //InvalidCastException
        }
    }

` I am not good at casting at all, I have tried return (System.string) obj. I tried to create a list with System.string data type with the help of foreach in the TestDashboard1(). Those of course failed. Could anyone kindly point me in the right direction? PS: if anyone is wondering why I am using the generic method here, see https://stackoverflow.com/questions/870697/unable-to-cast-object-of-type-system-dbnull-to-type-system-string

3 replies

CC#

•Created by morry329# on 1/30/2025 in #help

✅ NullPointException in the Update/Post method, but not in the Get Method

I started feeling puzzled at this NullPointException in this code

[HttpGet]  
    public IActionResult EditListingJ(int? Id)      
    { 
        try  
        {
            var ListingDTO_DBTable = _context.ListingDTO_DBTable.Find(Id);  
            if (ListingDTO_DBTable != null)  
            {  
                ListingProjectsDTO dtoModelEdit = new ListingProjectsDTO()
                {
                    Id = ListingDTO_DBTable.Id,
                    ListingName = ListingDTO_DBTable.ListingName
                }; 
                Console.WriteLine($"Got it"); //The GET method is fine, it grabs the id 
                return Json(dtoModelEdit);  
            } 
            
            return Json(null);  
            
        }  
        catch (Exception ex)  
        {  
            
            return null;  
        }  
    }  
    
    [HttpPost]  
    public IActionResult EditListingJ(ListingProjectsDTO editedDtoModel)      
    {
        if (ModelState.IsValid)
        {
                 //NullPointException!! why does this line stay always null, I don't understand   
                 ListingProjectsDTO _listingProjectsDtoEdit = _listingProjectsDtoRepository.getListingProjectsDto(editedDtoModel.Id);
                 _listingProjectsDtoEdit.Id = editedDtoModel.Id;
                 _listingProjectsDtoEdit.ListingName = editedDtoModel.ListingName;
                _context.ListingDTO_DBTable.Update(_listingProjectsDto);              
                _context.SaveChanges();  
                return Json(_listingProjectsDto);  
            

        }
        return Json(null);
    }

[HttpGet]  
    public IActionResult EditListingJ(int? Id)      
    { 
        try  
        {
            var ListingDTO_DBTable = _context.ListingDTO_DBTable.Find(Id);  
            if (ListingDTO_DBTable != null)  
            {  
                ListingProjectsDTO dtoModelEdit = new ListingProjectsDTO()
                {
                    Id = ListingDTO_DBTable.Id,
                    ListingName = ListingDTO_DBTable.ListingName
                }; 
                Console.WriteLine($"Got it"); //The GET method is fine, it grabs the id 
                return Json(dtoModelEdit);  
            } 
            
            return Json(null);  
            
        }  
        catch (Exception ex)  
        {  
            
            return null;  
        }  
    }  
    
    [HttpPost]  
    public IActionResult EditListingJ(ListingProjectsDTO editedDtoModel)      
    {
        if (ModelState.IsValid)
        {
                 //NullPointException!! why does this line stay always null, I don't understand   
                 ListingProjectsDTO _listingProjectsDtoEdit = _listingProjectsDtoRepository.getListingProjectsDto(editedDtoModel.Id);
                 _listingProjectsDtoEdit.Id = editedDtoModel.Id;
                 _listingProjectsDtoEdit.ListingName = editedDtoModel.ListingName;
                _context.ListingDTO_DBTable.Update(_listingProjectsDto);              
                _context.SaveChanges();  
                return Json(_listingProjectsDto);  
            

        }
        return Json(null);
    }

` In the Get method it grabs the id but the following Post method it does not and crashes into NullPointException. Seems to me like the GET method was able to refer to the row existing in my DB. However that does not seem to be the case for the Post method. Could anyone help me understand why? My code: https://pastebin.com/pXHYHfKM

46 replies

CC#

•Created by morry329# on 1/17/2025 in #help

edited data/user input not saved in db

1 replies

CC#

•Created by morry329# on 1/3/2025 in #help

The app does not allow edits to the pre-existing card view contents

2 replies

CC#

•Created by morry329# on 12/23/2024 in #help

Unable to create an object of type 'JsonContext'

I have fought this error for about an hour and finally gave up - would like a second set of eyes. I wanted to use dotnet ef migrations add InitialCreate which prompted this error Could you kindly point me in the right direction? https://pastebin.com/GuxUApaW

8 replies

CC#

•Created by morry329# on 12/21/2024 in #help

✅ System.InvalidOperationException: No database provide has been configured for this DbContext

It is all about this newbie error

System.InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the 'DbContext.OnConfiguring' method or by using 'AddDbContext' on the application service provider. If 'AddDbContext' is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.

System.InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the 'DbContext.OnConfiguring' method or by using 'AddDbContext' on the application service provider. If 'AddDbContext' is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.

I have no clue what triggered all this. Could kindly point me in the right direction? https://pastebin.com/RbkExv6j This is full code and full exception message for your reference.

7 replies

CC#

•Created by morry329# on 12/19/2024 in #help

Edit view directs to 404 not found

A beginner's mistake - the problem is that i have been getting Site Not Found 404 error (as per screenshot) while I wanted to display the edit dashboard view on localhost:https://imgur.com/a/mw5wBkD i think the connection between my view (html and js) and controller has gone wrong: https://pastebin.com/n4cfnwLp Could anyone kindly point out what I have been missing out here?

6 replies

CC#

•Created by morry329# on 12/1/2024 in #help

Edit function does not work

So I would like a second set of eyes. I wanted to try editing the pre-existing record on my card view (see the screenshot attached) like Beachfront Villa -> Beachfront Villa 8. Even this easy modification does not succeed, as on clicking the save button I got "record not found" And this comes from here in the controller

 [HttpPost]
    public async Task<IActionResult> Update(ListingProjects updatedUserModelRef)
    {
        
        
        if (oldListingProjects == null)
        {
            if (Request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                return Json(new { success = false, message = "Record not found." }); //this is the error i see on View
            }
            return NotFound();
        }

 [HttpPost]
    public async Task<IActionResult> Update(ListingProjects updatedUserModelRef)
    {
        
        
        if (oldListingProjects == null)
        {
            if (Request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                return Json(new { success = false, message = "Record not found." }); //this is the error i see on View
            }
            return NotFound();
        }

and this is what the frontend devtool says: https://imgur.com/a/xs8LLlD my database has not the id "1" referred in that devtool:

 mysql> Select * from ListingDBTable;
+----+----------------------+----------------------------------+------------+------------+
| Id | ListingName          | ImageUrl                         | CategoryId | LocationId |
+----+----------------------+----------------------------------+------------+------------+
|  5 | Beachfront Villa     | http://example.com/villa.jpg     |          1 |          1 |
|  6 | hidden moon building | hiddenmoon                       |          1 |          1 |
| 74 | New Listing          | http://example.com/new_image.jpg |          1 |          1 |
+----+----------------------+----------------------------------+------------+------------+

 mysql> Select * from ListingDBTable;
+----+----------------------+----------------------------------+------------+------------+
| Id | ListingName          | ImageUrl                         | CategoryId | LocationId |
+----+----------------------+----------------------------------+------------+------------+
|  5 | Beachfront Villa     | http://example.com/villa.jpg     |          1 |          1 |
|  6 | hidden moon building | hiddenmoon                       |          1 |          1 |
| 74 | New Listing          | http://example.com/new_image.jpg |          1 |          1 |
+----+----------------------+----------------------------------+------------+------------+

` my save button on View should have been picking up any ids listed here (5,6, or 74) but as the devtool shows it picks up 1 instead. i suppose if it picks up 5,6,74 it will let me edit the ListingName property. so could anyone kindly point me in the right direction? Relevant code snippets here https://pastebin.com/9U9zjvaG

20 replies

CC#

•Created by morry329# on 11/29/2024 in #help

✅ always gets the invalid data received

I have been creating a simple CRUD app with the ASP.NET. My update function does not work as expected: the save button triggers the error message "invalid data received" ; somehow the model reference is considred null on clicking the save button

 
//clicking the save btn prompts this method to work
public async Task<IActionResult> Update(ListingProjects updatedUserModelRef)
    {
        if (updatedUserModelRef == null || updatedUserModelRef.ListingName == null)
        {
            if (Request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                return Json(new { success = false, message = "Invalid data received." }); //however it always falls into this invalid message..
            }
            return NotFound();
        }

 
//clicking the save btn prompts this method to work
public async Task<IActionResult> Update(ListingProjects updatedUserModelRef)
    {
        if (updatedUserModelRef == null || updatedUserModelRef.ListingName == null)
        {
            if (Request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                return Json(new { success = false, message = "Invalid data received." }); //however it always falls into this invalid message..
            }
            return NotFound();
        }

could anyone kindly advice me on why the save button does not save the user input as expected? the full code here https://pastebin.com/4C2aYF78

2 replies

CC#

•Created by morry329# on 11/11/2024 in #help

Insert Method does not insert or save the user input as wanted

I have a working UI with a text field to enter a property name like "Ca* Oro Bridge" on my MVC view. The save button is also displayed on the view. Onclick it does not save the userinput in the text field (henceforth it is also not saved in the DB). I have debugged the follwing code responsible for handling user inputs

   public IActionResult InsertListings()
   {
       return View();
   }
    
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult InsertListings([Bind("ListingName")] ListingProjects listingProject) // Change to ListingProjects model
    {
        
        try
        {
            if (ModelState.IsValid)
            {
                _context.ListingDBTable.Add(listingProject);
                _context.SaveChanges();
                return RedirectToAction("TestDashboard1"); // Redirect to dashboard
            }
            else
            {
                // Model is invalid, handle it (e.g., show validation errors)
                return View(listingProject); // Return the view with error messages
            }
        }
        catch (DbUpdateException dbUpdateException)
        {
            ModelState.AddModelError("", "Unable to save changes. " +
                                         "Try again, and if the problem persists " +
                                         "see your system administrator.");
        }

        return View(listingProject);
    }

   public IActionResult InsertListings()
   {
       return View();
   }
    
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult InsertListings([Bind("ListingName")] ListingProjects listingProject) // Change to ListingProjects model
    {
        
        try
        {
            if (ModelState.IsValid)
            {
                _context.ListingDBTable.Add(listingProject);
                _context.SaveChanges();
                return RedirectToAction("TestDashboard1"); // Redirect to dashboard
            }
            else
            {
                // Model is invalid, handle it (e.g., show validation errors)
                return View(listingProject); // Return the view with error messages
            }
        }
        catch (DbUpdateException dbUpdateException)
        {
            ModelState.AddModelError("", "Unable to save changes. " +
                                         "Try again, and if the problem persists " +
                                         "see your system administrator.");
        }

        return View(listingProject);
    }

` I am not versed in the world of debugging, but it looks like the HttpGet method refers or returns null. InsertListing method (HttpPost method) deems it as !ModelState.Isvalid (which means my code does not save the input at all) Now I don't quite understand what caused all this null and invalidity. https://pastebin.com/DhCg4Md2 Can anyone kindly point me in the right direction?

1 replies

CC#

•Created by morry329# on 11/8/2024 in #help

Save button does not save the inserted data