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I am building a website where there are products and you can leave reviews on products. I have a link on the product page that says "Leave a review"

In my code it looks like this:

@Html.ActionLink("Leave a Review", "AddReview", "Product", new { id = Model.ProductId }, null)

When I run my application the link works fine, but when I submit a review it crashes and says:

The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Product(System.String, Int32)' in 'MyProject.Controllers.ProductController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters

This error only occurs if I have new { id = Model.ProductId } in my ActionLink.

This may seem like the ProductId is null, but that isn't possible. To load up the product page in the first place a ProductId is needed, plus I use a RenderAction that displays reviews about that product on the page using that same id:

@{Html.RenderAction("Reviews", "product", new { id = Model.ProductId});}

So basically, why am I getting this error? Does it have something to do with there being a GET and POST AddReview method? I don't think it should considering the link would pull the GET and when I submit the form it should be a POST. How do I get the productId into the form?

EDIT To answer some questions:

My form looks like this:

@using (Html.BeginForm("AddReview", "Product")) { <p>Title @Html.TextBoxFor(x => x.Title)</p> <p>Rating: @Html.TextBoxFor(x => x.Rating)</p> <p>Body: @Html.TextBoxFor(x => x.Body)</p> <input type="submit" value="Save"/> Html.ActionLink("Cancel", "Index", "Home"); }

My generated tag looks like this:

<a href="/Product/AddReview?ProductId=9">Leave a Review</a>

EDIT

After having fixed the link issue I realized that the reason I was still getting an error was because of a RedirectToAction call was broken in my controller. What a stupid mistake!

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  • 1
    What does the code to create the form look like? Commented Apr 16, 2012 at 16:30
  • How does the <a> tag look in the generated HTML when you browse the source? Commented Apr 16, 2012 at 16:35
  • I have added both of these to my original post. Commented Apr 16, 2012 at 16:37
  • Can we see the actions in your ProductController that you are using? It feels to me as if you think you are passing one parameter, but you're instead sending another. I would like to see what's going on in your controller. Commented Apr 16, 2012 at 16:55
  • I fixed it. Shyju's answer fixed my link and then I realized that something else was broken in my controller. Commented Apr 16, 2012 at 17:05

3 Answers 3

Reset to default
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@Html.ActionLink("Leave a Review", "AddReview", "Product", new { @id = Model.ProductId }, null)

This should generate a link like below if you have a valid valie in your ProductId property for this model

<a href="/Product/AddReview/9">Leave a Review</a>

Make sure you have the ProductId Property value loaded properly.

you may use @ symbol as a prefix to parameters which has the same name as of HTML attribues. See i used @id instead of id

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2 Comments

This generates the proper link. I still get the error and I suspect that's because I'm not loading the value into my form properly...
And yet the review still posts.
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<a href="/Product/AddReview?ProductId=9">Leave a Review</a>

is not good. You should get:

<a href="/Product/AddReview/9">Leave a Review</a>

or:

<a href="/Product/AddReview?id=9">Leave a Review</a>

because your controller action expects a non-nullable int parameter called id. The reason you are getting this wrong url might be because you have messed up with your routes.

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3 Comments

I haven't touched my routes though. It's the default {controller}/{action}/{id} setup.
Maybe it's your form then. Have you tried including the route parameter: @using (Html.BeginForm("AddReview", "Product", new { id = Model.ProductId }, FormMethod.Post))?
So, I get the error but the reviews still post. That's silly.
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It sounds like you are not setting the ProductId in the form. You either need to set the form action to include the id in the route: @Html.BeginForm("AddReview","Product", new {Id = Model.ProductId}) or include a hidden input for the productId, e.g. @Html.Hidden("id",Model.ProductId")

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3 Comments

How do I pass the ID into the form then?
@DarinDimitrov, it is better to pass the ID in the form action or in a hidden? Pros and cons...
@Romias I think the form value wins if they are different.

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