Problem to retrieve JSON after AJAX call

I have made an AJAX function with jQuery. The function works properly, and server return a JSON, but I can't use it in m开发者_JAVA技巧y JS script

Server side :

$array = array();

$array["count"] = count($accounts_list)."";

    for($i=0; $i<count($accounts_list); $i++)
    {
        $account = $accounts_list[$i];

        $array["marker"]["name"] = $account->name;
        $array["marker"]["lat"] = $account->map_latitude;
        $array["marker"]["lon"] = $account->map_longitude;
    }

    echo json_encode($array);

Client side :

$.ajax({  
    type: "POST",  
    url: "index.php?module=cap_Maps&action=AddMarkers", 
    data: dataString, 
    dataType: "json",
    success: function(data) {
        if (data == "error"){
            $(".tr_legend").before("<tr><td colspan='2' id='error'><span class='error_maps'>Erreur lors du chargement des marqueurs</span><td><tr>");
        }
        else {
            alert(data);
                var obj = jQuery.parseJSON( data )
                alert (obj.count);
        }

    }  
});

JSON returns by server:

{"count":"371","marker":{"name":"WAMPFLER","lat":"49.02751610","lon":"2.10611230"}}

Function alert(data) returns my JSON, but if I try to parse it with jQuery.parseJSON( data ), It doesn't work and alert(obj.count); doesn't open.

EDIT

I have add error function:

error: function (XMLHttpRequest, textStatus, errorThrown) {
                    alert("XMLHttpRequest="+XMLHttpRequest.responseText+"\ntextStatus="+textStatus+"\nerrorThrown="+errorThrown);
                },

And error occured :

XMLHttpRequest={"count":"358"}
textStatus=parsererror
errorThrown=Invalid JSON: {"count":"358"}

EDIT

If I had contentType: "application/json", in my AJAX, I can return a static string which is considered as json, but if I try to execute other php code on my server, AJAX returns an 500 Internal server error

Try this :

var json = jQuery.parseJSON('{"count":"371","marker":{"name":"WAMPFLER","lat":"49.02751610","lon":"2.10611230"}}');

alert(json.count);

maybe you forget to give a string ' ' to parseJSON.

From jQuery.ajax:

The json type parses the fetched data file as a JavaScript object and returns the constructed object as the result data.

So you don't need jQuery.parseJSON, as the returned string already is parsed.

instead of using parseJson can you try just using eval.

$.ajax({  
    type: "POST",  
    url: "index.php?module=cap_Maps&action=AddMarkers", 
    data: dataString, 
    dataType: "text",
    success: function(data) {
        if (data == "error"){
            $(".tr_legend").before("<tr><td colspan='2' id='error'><span class='error_maps'>Erreur lors du chargement des marqueurs</span><td><tr>");
        }
        else {
            alert(data);
                var obj = eval(data);
                alert (obj.count);
        }

    }  
});

HTH.

It looks like you are not sending the JSON with proper format from your server try to use json_encode() function.

The output buffer didn't empty so AJAX received buffer content + JSON so it wasn't a valid JSON.

I use ob_clean() on server side just before output my JSON and it solves the problem.