Object reference not set to an instance of an object, parameter is null

Question

I am having issues with passing an argument from my view to my controller

I have this code fragment in my view:

<a class="btn-simple" onclick="submitDetails('Dashboard', 'Cancel', '<%=Model.Data.Id %>', $('form'));">save</a>

and this is from my controller:

[HttpPost]
public ActionResult Cancel(string id, FormCollection collection)
{
       var appt = Application.Session.GetObjectFromOid<Appointment>(new ObjectId(id));
}

I get an error saying that "id" is null, but when I test Model.Data.Id in the view, it is not null.

And this is my submitDetails function:

function submitDetails(controller, method, id, form) {
    form.ajaxSubmit({ target: '#itemdetails' });

}

What I am trying to accomplish is getting back to my controller from a button in the view, the "[HttpPost]" version of the method that originally called the view

because your just passing id back as a string. The string doesn't know the same things your model knows. In this case it is looking for id as part of the url string i.e. controller/view/id. you have to pass the id from the model. — Brian
– Brian, Commented Mar 7, 2012 at 15:25
I am very new at this so I might not be doing what I am trying to do at all. I just want to get to the [HttpPost] version of Cancel() when I press the "Save" Button — caradrye
– caradrye, Commented Mar 7, 2012 at 15:26
<%=Model.Data.Id %> - Are you sure Model.Data isn't null? — M.Babcock
– M.Babcock, Commented Mar 7, 2012 at 15:29

Darin Dimitrov · Accepted Answer · 2012-03-07 15:46:15Z

1

Make sure that the form you are submitting contains a hidden field with the id or it is passed as query string parameter:

<% using (Html.BeginForm("Dashboard", "Cancel", new { id = Model.Data.Id })) { %>
    ...
<% } %>

or if you want to pass a dynamic url you could do the following:

<a class="btn-simple" onclick="submitDetails('<%= Url.Action("Dashboard", "Cancel", new { id = Model.Data.Id }) %>', $('form'));">save</a>

and then:

function submitDetails(url, form) {
    form.ajaxSubmit({ url: url, target: '#itemdetails' });
}

UPDATE:

And if you want to avoid the submitDetails javascript method and have your anchor be the submit button of the form:

<% using (Html.BeginForm("Dashboard", "Cancel", new { id = Model.Data.Id })) { %>
    ...

    <button class="btn-simple" type="submit">save</button>
<% } %>

edited Mar 7, 2012 at 15:46

answered Mar 7, 2012 at 15:32

Darin Dimitrov

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12 Comments

caradrye Over a year ago

I would like to avoid using submitDetails altogether if that is possible

Darin Dimitrov Over a year ago

@user1229309, in this case you could make this anchor be the submit button for your form. I have updated my answer with an example.

Brian Over a year ago

then you can add a hidden field as DD suggested with the value of model.data.id and grab that in the form collection. <input type="hidden" id="id" value="<%Model.Data.Id%>" />

Darin Dimitrov Over a year ago

@user1229309, how does the action attribute of the form look like? Does it contain the id? Like for example action="/Dashboard/Cancel/123"?

caradrye Over a year ago

@DarinDimitrov I dont know what you mean by the action attribute

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