kendo grid paging does not work

How do I assign rows number in total property in kendo grid? I used json to fill the data:

if ($result = mysqli_query($con,$sql)) {   
    while($obj = mysqli_fetch_object($result)) {
        $arr[] = $obj;
    }
}
echo "{\"list\":" .json_encode($arr). "}";      

But paging does not work with total = total or function ! I don't know where is my grid problem!!

$(document).ready(function () {
                var record = 0;
                var grid = $("#grid").kendoGrid({

                    dataSource: {
                        transport: {
                            read: {
                                url: "<?php echo $path?>/contractors.php?m=read&f=subcat",
                                dataType: "json"
                            }
                        },
                        schema: {
                            data: "list",
                            model: {
                                id: "id",
                                fields: {
                                    company: { type: "string" },
                                    firstname: { type: "string" },
                                    lastname: { type: "string" }

                                }
                            },
                            total: function (response) {
                                return $(response.data).length;
                            }

                        },
                        pageSize: 20,
                        serverPaging: true
                    },
                    pageable: true  ....

From what I see in your code, total function should be:

total: function (response) {
    return response.list.length;
}

What you are returning from PHP is a JSON object that includes an array in a field called list and this is a JSON object (once in KendoUI total). So, the reference to the array is response.list and the length response.list.length.