jQuery.ajax returns 400 Bad Request

Question

This works fine:

jQuery(\'#my_get_related_keywords\').click(function() {
    if (jQuery(\'#my_keyword\').val() == \'\') return false;
        jQuery.getJSON(         


        

Answer 1

I was getting the 400 Bad Request error, even after setting:

contentType: "application/json",
dataType: "json"

The issue was with the type of a property passed in the json object, for the data property in the ajax request object.
To figure out the issue, I added an error handler and then logged the error to the console. Console log will clearly show validation errors for the properties if any.

This was my initial code:

var data = {
    "TestId": testId,
    "PlayerId": parseInt(playerId),
    "Result": result
};

var url = document.location.protocol + "//" + document.location.host + "/api/tests"
$.ajax({
    url: url,
    method: "POST",
    contentType: "application/json",
    data: JSON.stringify(data), // issue with a property type in the data object
    dataType: "json",
    error: function (e) {
        console.log(e); // logging the error object to console
    },
    success: function () {
        console.log('Success saving test result');
    }
});

Now after making the request, I checked the console tab in the browser development tool.
It looked like this:

responseJSON.errors[0] clearly shows a validation error: The JSON value could not be converted to System.String. Path: $.TestId, which means I have to convert TestId to a string in the data object, before making the request.

Changing the data object creation like below fixed the issue for me:

var data = {
        "TestId": String(testId), //converting testId to a string
        "PlayerId": parseInt(playerId),
        "Result": result
};

I assume other possible errors could also be identified by logging and inspecting the error object.