How to resolve null json string passed to mvc controller?

Question

I created a table using a list of model objects. Then passed the row data to an Ajax post when a button on that row is clicked.

Within the Ajax Post .stringify is called on that row data passed down. When I check the values of the data passed on the wire in Dev Tools I can see that they are populated:

["66", "[email protected]", "2009", "test",…]
0
:
"66"
1
:
"[email protected]"
2
:
"2009"
3
:
"test"

But when I step into the controller POST action that is called from client side. The expected JSON string is null / empty. My thoughts are that maybe this is beacause stringify has no property names to associate with each value in the array.

Question:

How can you resolve null json string passed to mvc controller?

Here is a gist of the implementation below -

Model:

public class Status
{

        [Key]
        public int ID { get; set; }


        public string Contact_Email { get; set; }

        public string RID { get; set; }

        public string Name { get; set; }



    }

Table and AJAX post method:

     <table id="statusTable" class="table table-hover table-bordered results">
            <thead>
                <tr>
                    <th>ID</th>
                    <th>Email</th>
                    <th>RID</th>
                    <th>Name</th>
                    <th>Update Record</th>


                </tr>
            </thead>
            <tbody>
            @foreach (var row in Model.ReleaseStatus)
            {
                    <tr>
                        <td>@Html.Raw(row.ID)</td>
                        <td>@Html.Raw(row.Contact_Email_Name)</td>
                        <td>@row.RID</td>
                        <td>@row.Name</td>
                        <td><button type="submit" class="btn btn-success">Update</button></td>
                    </tr>
              }
            </tbody>

        </table>



 $(".btn-success").click(function () {
            var $td = $(this).closest('tr').children("td"),
            len = $td.length;
            var tableData = $td.map(function (i) {
                if (i < len - 1)
                    return $(this).text();
            }).get();

            console.log(tableData);

            //Post JSON data to controller
            $.ajax({
                type: "POST",
                url: 'updateStatus',
                data: JSON.stringify(tableData),
                contentType: "application/json; charset=utf-8",
                success: function (response) {
                    console.log("post success");
                },
                error: function (request) {
                    console.log("post error" + request.error);
                }

            });


        });

And finally the POST method in the MVC controller:

    [HttpPost]
    public ActionResult updateStatus(stirng jsonString)
    {
        //deserialise the json to a Status object here
    }

Why are you trying to bind to a string instead of your model. Your method should be public ActionResult updateStatus(Status model) and the data var data = { ID: 66, Contact_Email: '[email protected]', etc } — user3559349
– user3559349, Commented Sep 23, 2016 at 13:29
I did try specifying a onject in the mvc action, like updateStatus(Status vm) the object is null during the post. I think the main issue is that my data being passed down in jquery has no name attached to the values? — Brian Var
– Brian Var, Commented Sep 23, 2016 at 13:33
Yes, that why you need generate and object (as per my previous comment) and in the ajax remove contentType: "application/json; charset=utf-8", and use data: data, — user3559349
– user3559349, Commented Sep 23, 2016 at 13:36
But your not editing any properties of your model, so what is the point of this? — user3559349
– user3559349, Commented Sep 23, 2016 at 13:39

Darren Wainwright · Accepted Answer · 2016-09-23 13:46:50Z

7

Your controller needs to be created to accept the actual object, and not the json string.

By this i mean

[HttpPost]
public ActionResult updateStatus(stirng jsonString)
{
   //deserialise the json to a Status object here
}

Should be

[HttpPost]
public ActionResult updateStatus(Status vm)
{
   //no need to deserialize - was already done by the model binder
}

In order for the model binder to bind your json to Status you would need to pass a json object that replicates your viewmodel.

{
 ID:yourId, 
 Contact_Email:yourContactEmail, 
 RID:YourRID, 
 Name:yourName
}

In pseudo-code, you could:

var statusData = {
     ID:tableData[0], 
     Contact_Email:tableData[1],
     RID:tableData[2], 
     Name:tableData[3]
};

Then in your ajax call,

data: JSON.stringify(statusData),

edited Sep 23, 2016 at 13:46

answered Sep 23, 2016 at 13:27

Darren Wainwright

30.8k22 gold badges87 silver badges131 bronze badges

Sign up to request clarification or add additional context in comments.

10 Comments

user3559349 Over a year ago

This wont do anything unless OP also generates the object in the view correctly instead of posting back an array

Brian Var Over a year ago

I tried passing in a Status object before the json string, and each value in the object is null when it reaches the action method. I think it is because my data doesn't specify the name if each value?

Darren Wainwright Over a year ago

@BrianJ - I added a little more explanation to why you're getting nulls. This is what Stephen refers to in his comment on this answer.

user3559349 Over a year ago

@BrianJ, All your posting currently is an array of values - it can b=never be serialized to anything other that List<object> (adding [DisplayName] will not do anything to solve the issue)

Darren Wainwright Over a year ago

@BrianJ - do this for your date. Create_Date: new Date(tableData[5]) - give it an actual date.

|

bricer · Accepted Answer · 2016-09-23 13:33:00Z

-2

try the from body attribute

[HttpPost]
public ActionResult updateStatus([FromBody]Status status)
{
    //add the serialize attribute on your model 
}

answered Sep 23, 2016 at 13:33

bricer

1

Collectives™ on Stack Overflow

How to resolve null json string passed to mvc controller?

2 Answers 2

10 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

10 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related