从jQuery中的链接提交带有参数的表单

Question

I am trying to save data in database in background through a link, and to give download functionality to that link in front end. but it gives an error.

my script is -

<script>
$(document).ready(function(){
    $("#download").click(function(){
        var me = $(this), data = me.data('params');
        saveData(me);
});

function saveData(me){  
$.ajax({
       type: "POST",
       url: "download_counter.php",
       data: { client_id: "<? echo $client_id;?>", candidate_id: me }
    });
}
});
</script>

this is the link (It looks fine)

<a href="upload/<? echo $download;?>" id="download" data-params="{'ca_id':'<? echo $ca_id;?>'}"><button name="download"></button></a>

download_counter.php looks like -

<?
if (isset($_POST['candidate_id'])) { // Form has been submitted.
    $candidate_id = $_POST['candidate_id'];
    $client_id= $_POST['client_id'];
    $date = date("Y-m-d");
    echo "client - ".$client_id;
    echo "candidate - ".$candidate_id;
    $query = "INSERT INTO `downloads`(`client_id`, `candidate_id`, `download_date`) VALUES ('".$client_id."', '".$candidate_id."', '".$date."')";
    $result = mysql_query($query);  
}
?>

when i click the link, it lets download the file but database do not updates. Please help.

Answer 1

Check jquery click event handler , which says

// say your selector and click handler is somewhat as in the example
$("some selector").click({param1: "Hello", param2: "World"}, some_function);

// then in the called function, grab the event object and use the parameters like this--
function some_function(event){
    alert(event.data.param1);
    alert(event.data.param2);
}

Answer 2

There is an error with passing parameter to function saveData, so your ajax request not occur:

$(document).ready(function(){
    $("#download").click(function(){
        var me = $(this), data = me.data('params');
        saveData(data); // was me
});

Answer 3

database is updating now, but it is not getting value of candidate_id.

i did this -

<script>
$(document).ready(function(){
    $("#download").click(function(){        
        $("#count").hide();
        var me = $(this), data = me.data('params');
        saveData(data); // was me
});

function saveData(data){  
$.ajax({
       type: "POST",
       url: "counter.php",
       data: { client_id: "2", candidate_id: data.ca_id }
    });
}
});
</script>

Answer 4

I think on click the data you are reading is a string and in the given format. 
And you are passing that as data, but since it is not an valid id, 
that value in the database is not updated.

Check this out