Empty parameter on a MVC 4 ApiController action

Question

I am passing a Javascript array of a collection of strings to a post action on my apicontroller, there is a data being sent ( i know this via fiddler ) but it doesn't seem to actually get to the controller action when i am debugging the code. My code is below, any help would be greatly appreciated.

Edit: Just to clarify, the controller action is called but the List stuffsId has a count of zero when there is a list being passed to it

Ajax/Javascript

my.sendStuffToController = function (stuffIds, completedHandler) {

        $.ajax({
            dataType: 'json',
            type: 'POST',
            url: my.stuffUrl,
            data: {
                stuffIds: stuffIds
            },
            success: function (data) {

                if (completedHandler !== undefined) {
                    completedHandler(stuffIds);
                }
            }
        });
    };

My ApiController Post Action

    // Post 
    public void PostAsync(List<string> stuffIds)
    {
        var clientProxy = this.proxyFactory.CreateClientProxy(Tokens.EndPoint);
        var clientChannel = clientProxy.GetClientChannel();

        try
        {
            clientChannel.DoStuffAsync(stuffIds);
        }
        finally
        {
            clientProxy.TryCloseAbortClientChannel();
        }
    }

Darrel Miller · Accepted Answer · 2013-03-11 16:19:23Z

1

dataType is used to specify the return type of the request. contentType is what you should be using to tell the server what you are sending.

answered Mar 11, 2013 at 16:19

Darrel Miller

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3 Comments

Philip Loyer Over a year ago

changing it from dataType to contentType didnt seem to do anything

Darrel Miller Over a year ago

@PhilipLoyer Did you set the content type to application/json ?

Philip Loyer Over a year ago

So it turns out that was part of the problem, that was a key part though. So here is what I did to solve it in totality. I changed public void PostAsync(List<string> stuffIds) to public void PostAsync([FromBody] IEnumerable<string> stuffIds) and in my javascript data: { stuffIds: stuffIds }, to data: JSON.stringify(stuffIds),

Sergii Kudriavtsev · Accepted Answer · 2013-03-11 15:33:17Z

0

One of the possible (and most common) problems with passing arrays as post parameters from jQuery is described here.

Short version:

Add

jQuery.ajaxSettings.traditional = true;

before your jQuery ajax() function call, i.e.

jQuery.ajaxSettings.traditional = true;
my.sendStuffToController = function (stuffIds, completedHandler) {

        $.ajax({
            dataType: 'json',
            type: 'POST',
            url: my.stuffUrl,
            data: {
                stuffIds: stuffIds
            },
            success: function (data) {

                if (completedHandler !== undefined) {
                    completedHandler(stuffIds);
                }
            }
        });
    };

Long version:

From some point in time jQuery started appending square brackets to variable name if the variable is array, i.e. in your case it will transmit 'stuffIds[]:value1 stuffIds[]:value2' etc. over the ajax call. ASP.NET MVC does not like that and refuses to accept such parameters. jQuery.ajaxSettings.traditional = true switches this jQuery 'feature' off.

answered Mar 11, 2013 at 15:33

Sergii Kudriavtsev

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1 Comment

Philip Loyer Over a year ago

That did remove the brackets, but i am still get a zero count when the apicontroller action fires.

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