Sending ajax post to mcv action

Leo Del Ciello 1

Hello

I am developing an Asp.net Core Mvc application in which I need to send , as usual, some data from an ajax call to an MVC action.
The ajax code is as follows :

**function ShowHideAttivita(model, idriga) {
    var dati =model;
    var idcommessa = $('#IdselectCommessa' + idriga + ' option:selected').val();
    $.ajax({

        url: 'cambiaCommessa',
        type: 'POST',
        dataType: "html",
        contentType: "application/json",
        data: dati,
        success: function (result) {
            $('#IdrigaSezioneCommessa' + idriga).replaceWith(result);
        }, error: function (error) {
            var x = error.responseText;
            VisualizzaMessaggio('errore', 'E', '');
        }
    });
}**

The corresponding MVC Controller Action which is listening is as follows ;

**[HttpPost]
        public async Task<ActionResult> cambiaCommessa( RapGiornalieroExtended dati)
        {
            try
            {
                DettaglioPresenze DP = new DettaglioPresenze();
                return PartialView("~/Views/Home/_rigaCommessa.cshtml", DP);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }**

It seems I can call the action correctly, but the content in the data sent is null (the fields of the "dati" parameters).No matter how I change the code in the sending Ajax, when I break into the Action , the best result I can get is getting a "dati" parameter (which is a complex type itself) with all its fields null, in spite of the fact that, in the sending ajax, i verified the content is not null.
Most inquietingly, another application from which this same bunch of code is taken works perfectly , and there are no differences in the Ajax, in the Controller, in the Action, and in the data content itself, between the two situations.

Any suggestions ?
Thanks

SurferOnWww 3,066 Reputation points

2021-02-02T00:15:33.603+00:00

What is the "model" of 1st argument in the ShowHideAttivita method? What is the RapGiornalieroExtended class in the cambiaCommessa method?

Have you seen what are sent and received between the client and server by using a capture toll such as the Fiddler and confirmed the header and contents are proper as expected?
Leo Del Ciello 1 Reputation point

2021-02-02T07:51:13.077+00:00

I didn't check the post header, but I am 100% sure that the "model" parameter is correctly set. It is a js version of the RapGiornalieroExtended object which is the parameter expected by the action.
This object (class) is made up of three member the first of which is another class, and the second and third are respectively a list of objects and a dictionary of strings.
Both the list and dictionary members contain values , the first member which is a scalar object is a null reference.
What i expect on the action side is to receive the same values but I verified instead that all the three members are null references.

Actually, as I verified yesterday after posting this question, is seems the data : .... parameter of the ajax call is ignored, since as I remove it nothing changes in the action behavior.

Do you think I should check the post header ?
Leo Del Ciello 1 Reputation point

2021-02-02T08:39:43.333+00:00

By checking the post header I see that, in spite of the fact that I set the ajax call's content-Type parameter to "application/json", in the header I end up having , from time to time , "application/www-url-encoded" ... but as I said this is not sistematic, this just happens randomly.
Anyway, no matter what content-Type is set, I always have, in the action parameter, an object with all the three members having null references.
SurferOnWww 3,066 Reputation points

2021-02-02T08:48:00.51+00:00

Have you seen what are sent and received between the client and server by using a capture toll such as the Fiddler and confirmed the header and contents are proper as expected?

In your jQuery ajax code you include contentType: "application/json". It means that the server must receive JSON string.

You say that the dati (= model) is "js version of the RapGiornalieroExtended object." But the javascript object will be converted to application/x-www-form-urlencoded format, not JSON.
Leo Del Ciello 1 Reputation point

2021-02-02T09:04:33.573+00:00

I don't have any capture toll and am not allowed to install since my laptop belongs to the company.
All I can say is that, checking from the Web Browser debugger, the request payload is what I expect it to be (most of the times but not always).
I am not sure I get you when you say that "the object will be converted to "application/x-www-form-urlencoded" : is this by default ?
and in case, this means that I should do something like :

....
data : JSON.strinfigy(dati),
....

????

If yes, this is a solution I already attempted and didn't work either...
SurferOnWww 3,066 Reputation points

2021-02-02T10:10:24.5+00:00

IE, Chrome. Edge, Firefox has tool to capture the request and response. You have to use it to see what’s going on between the client and server. You can’t shoot in the dark.

Please read the jQuery API documentation.

https://api.jquery.com/jQuery.ajax/

See "data" section. It describes that:

When data is an object, jQuery generates the data string from the object's key/value pairs unless the processData option is set to false. For example, { a: "bc", d: "e,f" } is converted to the string "a=bc&d=e%2Cf".

Note that "a=bc&d=e%2Cf" is not JSON string.

You said you have already tried JSON.strinfigy(dati) but it does not work. I don’t know why. But at least I am sure that you have to send JSON string to the server which expects to receive JSON string.
Fei Han - MSFT 306 Reputation points Microsoft Vendor

2021-02-07T08:07:33.587+00:00

Hi @LeoDelCiello-425, please check the actual request and posted data that you made from ajax client in browser F12 developer tool Network tab. And if possible, you can share the details about request headers and payload, so that we can help troubleshoot the issue better. Besides, you can try to apply [FromBody] attribute to your action parameter, like this public async Task<ActionResult> cambiaCommessa([FromBody]RapGiornalieroExtended dati).

1 answer

murtaza gandhi 81 Reputation points

2021-02-05T10:14:43.957+00:00

Hi,

Are you using submit button , type = submit or type = button.

type = button

may solve it

Regards.
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