Btukfyl

Here is my view (full view)

@model List<BlogPostLayoutModel>

@{

ViewData["Title"] = "Index";

}



@foreach (var item in Model)

{

<div class="row">

    <div class="col-md-12">

        <h2 class="text-center">

            @item.Title

        </h2>

        <div class="col-md-9 thumbnail">

            <img src="/home/getimage/@item.IDPost" />

        </div>

        <p>@item.Content</p>

    </div>

</div>

}

And here is Home controllers GetImage method

public async Task<ActionResult> GetImage(int id)

    {

        var post = await _blogContext.Posts.FirstOrDefaultAsync(m => m.IDPost == id);



        return File(post.Image, post.Image_Extension);

    }

When i debug, i can see that each object in Model has an id of ~1000 (some real number in database) but when i debug the GetImage method, it always get passed 0.

Routing definition:

app.UseMvc(routes =>

        {

            routes.MapRoute(

                name: "default",

                template: "{controller=Home}/{action=Index}/{pageNumber=1}");

        });

Controller method:

public async Task<IActionResult> Index(int pageNumber)

    {

        blogPages = BlogPages();

        ViewBag.pageNumber = pageNumber;

        ViewBag.blogPages = blogPages;

        List<BlogPostLayoutModel> bPLMList = PostsForBlogPage(pageNumber);

        return View(bPLMList);

    }

And BlogPostLayourModel definition (without the unnecessary methods):

public class BlogPostLayoutModel

{

    public int IDPost { get; set; }

    public string Title { get; set; }

    public string Content { get; set; }

    public string AuthorUserName { get; set; }

    public DateTime DateCreated { get; set; }

    public byte ImageFromPost { get; set; }

    public string Image_Extension { get; set; }

 }

So your route says that the third route parameter is called pageNumber. Now consider your image link:

<img src="/home/getimage/@item.IDPost" />

Post ID is going to be mapped to pageNumber when this request is being routed. Now take a look at the action declaration:

public async Task<ActionResult> GetImage(int id)

This says that the action expects a request to have a parameter called id. After the request is routed to this action, model binding happens, and during this process route and request parameters are being mapped to action's input. In this case there model binder is not going to find the id the action needs, because there is nothing in request with that name. The only parameter in there has a name pageNumber. Thus it initializes id with a default value, 0.

One way to fix this would be to use query string instead of route parameter, and this way explicitly name post ID as, well, id:

<img src="/home/getimage?id=@item.IDPost" />

Actually, using pageNumber as default parameter, is under normal circumstances, not really a wise choice.

You should alter your routing to:

app.UseMvc(routes =>

    {

        routes.MapRoute(

            name: "default",

            template: "{controller=Home}/{action=Index}/{id?}");

    });

This will break the code which uses pageNumber as default route, but you'll gain the fact that this will work:

<img src="/home/getimage/@item.IDPost" />

For other links, using pageNumber, you'll need the following syntax:

<img src="/home/getimage?pageNumber=@item.PageNumber" />

The motivation for this all, is due to the fact that:

• quite often, you'll need a (detail)record and is often queried by id


• pageNumber often comes with pageSize, so is basically often a more complex object.

Additionally, if you want to make the pageNumber a default parameter for a single action, you can mark it with the route attribute:

[Route("{pageNumber}")]

public async Task<IActionResult> Index(int pageNumber)

More information on routing can be found here and here (assuming you are using asp.net Core.