CODEWITHSUNDEEP
c#jqueryasp.net-mvcasp.net-mvc-3razor
e-on
e-on

Reputation: 1605

null values sent to controller after jQuery Post

I have a bit of code where I'm trying to send a Viewmodel back to the controller using Ajax post. If I write the code one way, it passes correctly, and another way it returns null or 0 values within the viewmodel.

The way that works:

$(document).ready(function () {
        $(".boxItem").change(function (event) {
            var url = "/Search/GetBoxChangeInfo";
            $.post(url, @Html.Raw(Json.Encode(Model)), function (data) {
                $("#column-1").html(data);
            });
        });
    });

And the way that returns null values:

$(document).ready(function () {
        $(".boxItem").change(function (event) {
            var url = "/Search/GetBoxChangeInfo";
            $.post(url, { json: @Html.Raw(Json.Encode(Model)) }, function (data) {
                $("#column-1").html(data);
            });
        });
    });

i need to use it the second way because I need to also pass parameters back about the selected value and ID, so it will look something like:

$(document).ready(function () {
        $(".boxItem").change(function (event) {
            var str = $(this).attr('id');
            var num = $(this).val();
            var url = "/Search/GetBoxChangeInfo";
            $.post(url, { json: @Html.Raw(Json.Encode(Model)), id : str, selected : num  }, function (data) {
                $("#column-1").html(data);
            });
        });
});

My controller looks like this btw:

[HttpPost]
public ActionResult GetBoxChangeInfo(EventViewModel json)
{ 
     //stuff
}

EDIT - as requested, here is EventViewModel structure

[JsonObject(MemberSerialization.OptIn)]
public class EventViewModel
{
    public int EventNumber { get; set; }
    public List<EventItemsViewModel> EventItems { get; set; }
    public List<LocationViewModel> Locations { get; set; }
    public int StartLocationID { get; set; }
    public bool Outbound { get; set; }
    public List<int> SelectedEvents { get; set; }
    public List<DurationsViewModel> Durations { get; set; }
}

Anyone know why this might be happening? Is there a limit to home much can be sent to the controller this way - it is quite a complex viewmodel, so wondered if that could be someting to do with it.

Thanks

Upvotes: 1

Views: 1776

Answers (4)

Michael Buen
Michael Buen

Reputation: 39393

I encountered the same error on ASP.NET MVC. On your model, you put ConvertEmptyStringToNull = false on your model's property's attribute: 

[DisplayFormat(ConvertEmptyStringToNull = false)]

E.g.

public class Person
{
    [DisplayFormat(ConvertEmptyStringToNull = false)]
    public string Lastname { get; set; }
    [DisplayFormat(ConvertEmptyStringToNull = false)]
    public string Firstname { get; set; }
    [DisplayFormat(ConvertEmptyStringToNull = false)]
    public string Middlename { get; set; }
}

I documented when I encountered the same thing at this post: http://www.ienablemuch.com/2011/08/empty-string-is-empty-string.html

Upvotes: 0

Darin Dimitrov
Darin Dimitrov

Reputation: 1038720

Like this:

$(document).ready(function () {
    $('.boxItem').change(function (event) {
        var str = $(this).attr('id');
        var num = $(this).val();
        var url = '@Url.Action("GetBoxChangeInfo", "Search")';
        $.ajax({
            url: url,
            contentType: 'application/json',
            data: JSON.stringify({ 
                json: @Html.Raw(Json.Encode(Model)), 
                id: str, 
                selected: num  
            }),
            success: function(data) {
                $("#column-1").html(data);
            }
        });
    });
});

Things to notice:

  • contentType: 'application/json'
  • JSON.stringify to convert the object into a JSON string
  • var url = '@Url.Action("GetBoxChangeInfo", "Search")'; to avoid hardcoding urls

Upvotes: 2

Cornel Urian
Cornel Urian

Reputation: 396

Use this http://api.jquery.com/jQuery.post/

$.ajax({ type: 'POST', url: url, data: data, success: success, dataType: dataType });

, I mean not shorthand Axaj Call. You have options like "success", "error", "completed" and can isolate issue.

Upvotes: 0

Mathew Thompson
Mathew Thompson

Reputation: 56429

Is there a limit to home much can be sent to the controller this way - it is quite a complex viewmodel, so wondered if that could be someting to do with it.

Yes there is and it's 1000 HTTP Collection keys and you can configure that yourself in the web.config. Try setting the value to 4000 first, then you can lower it a bit if you like. Try this:

<appSettings>
    <add key="aspnet:MaxHttpCollectionKeys" value="4000" />
</appSettings>

Upvotes: 1

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