Hello,

Thank you for the provided sample and additional information.

After further investigation I determined that this is the expected behavior of the grid, which was added as you specified in the given code from version 2018.2, and after the design changes, the GridDataSourceAction method accepts post requests only under json so that the given data can be bound to the grid.

What I propose as an approach is according to your custom logic and based on how the given application is built to check before making post requests to the controller action method whether the data is in the form of "application/x-www-form-urlencoded" that is query string or in the form of "application/json", that is, json. Based on this, you can transform all query string requests with a given function to json and only perform post requests to the controller action method of type json so that you do not experience the described behavior. You can implement different types of functions according to your custom logic to convert the query string of type "application/x-www-form-urlencoded" to the json data of type "application/json" and according to what exactly the query string is in your application. There are also many other options that you can look at as suggested in stack overflow and other articles and forums by doing your research.

However, I went through your sample in detail and made a sample function that converts the query string of type "application/x-www-form-urlencoded" to json of type "application/json" by taking the given string and splitting it first with the “&” character then the compiled array after splitting the string is looped and each pair of key and value is concatenated by the “=” character. In a given variable key and value are added and separated by a comma from the next pair then finally the JSON.stringify method is used to concatenate to json and the result is returned. The POST ajax request takes the query string and passes it to this function which converts it and makes a request of type json to the controller action method successfully.

function queryStringToJSON(qs) {
            var input = qs.split('&');
            var result = {};

            input.forEach(function (p) {
                var pair = p.split('=');
                var key = pair[0];
                var value = decodeURIComponent(pair[1] || '');

                if (result[key]) {
                    if (Object.prototype.toString.call(result[key]) === '[object Array]') {
                        result[key].push(value);
                    } else {
                        result[key] = [result[key], value];
                    }
                } else {
                    result[key] = value;
                }
            });
            return JSON.stringify(result);
        };

The described scenario could be observed here:

I have prepared small sample illustrating my suggestion which could be found attached here. Please test it on your side and let me know how it behaves.

I couldn't upload the file as it was too big.  See if you can access this link: