CODEWITHSUNDEEP
listviewjquery-mobilejsonp
Hans Van Lint
Hans Van Lint

Reputation: 33

JQuerymobile Listview populated through JSON Ajax call

I'm trying to populate a listview with json results. I've installed fiddler and can acknowledge that I do get the json results back. I positively validated the JSON results. However somehow they do not show up in the listview. I can't seem to find out where it goes wrong.

JSON results: [{"Id":1,"Title":"Electrical"},{"Id":2,"Title":"Piping"},{"Id":3,"Title":"Mechanical"},{"Id":4,"Title":"Software"}]

Code:

<!DOCTYPE html>
<head>
    <title></title>
    <meta name="viewport" content="width=device-width, initial-scale=1"> 
    <link rel="stylesheet" href="http://code.jquery.com/mobile/1.2.0/jquery.mobile-1.2.0.min.css" />
    <script src="http://code.jquery.com/jquery-1.8.2.min.js"></script>
    <script src="http://code.jquery.com/mobile/1.2.0/jquery.mobile-1.2.0.min.js"></script>
    <script src="http://ajax.microsoft.com/ajax/jquery.templates/beta1/jquery.tmpl.js"></script>
    <style>
    .count {
        position: absolute;
        font-size: 11px;
        font-weight: bold;
        padding: .2em .5em;
        top: 50%;
        margin-top: -1em;
    }

    .ui-li-aside {
        float: right;
        width: 50%;
        text-align: right;
        margin: 1.4em 0px 0px 0px !important;
        position: absolute;
        right: 25px; 
    }

    .ui-li-heading, .ui-li-desc {
        width: 90%;
        text-overflow: ellipsis;
    }

    strong { font-style: normal; }
    </style>

    <script type="text/javascript" >
        var hackerNews = (function($,undefined) {
            var pub = {}, $this = $(this);
            pub.init = function() {
                $("#btnRefresh").live("click", function () {
                    pub.getAndDisplayNews();
                });
                $this.bind("news.updated", function (e, news) {
                    displayNews(news);
                });
                $this.bind("news.updated", function(e, news) {
                    $("#itemCount").text(news.items.length);
                });
            };
            pub.getAndDisplayNews = function() {
                //$.mobile.loading();
                getNews(function () {
                    //$.mobile.loading();
                });
            };
            function getNews(callback) {
                $.ajax({
                    url: "http://localhost:31634/expertREST.svc/GetKnowledgeFields",
                    dataType: "jsonp",
                    success: function (data, textStatus, xhr) {
                        $this.trigger("news.updated", data);
                        if (callback) callback(data);
                    }
                });
            }
            function displayNews(news) {
                var newsList = $("#hackerNews").find(".newsList");
                newsList.empty();
                $("#newsItem").tmpl(news.items).appendTo(newsList).trigger("create");
                newsList.listview("refresh");
            }
            return pub;
        }(jQuery));
        hackerNews.init();
        hackerNews.getAndDisplayNews();
        </script>
</head>

<body>

<div data-role="page" id="hackerNews">
    <div data-role="header" data-backbtn="false">
        <a id="btnRefresh" href="#" data-icon="refresh">Refresh</a>
        <h1>Find-an-Expert &nbsp;<span id="itemCount" class="count ui-btn-up-c ui-btn-corner-all">0</span></h1>
    </div>
    <div id="content" data-role="content">
        <ol class="newsList" data-role="listview"></ol>
    </div>
</div>

<script id="newsItem" type="text/x-jquery-tmpl">
    <li data-messageId="${Id}" class="newsItem">
        <h3>${Title}</h3>
    </li>
</script>

</body>

Does anyone have a clue? Thanks

Upvotes: 3

Views: 2307

Answers (3)

Hans Van Lint
Hans Van Lint

Reputation: 33

Well, thanks for the feedback. I noticed the ajax call didn't even reach the success event so that made me think if there isn't anything wrong with the json I get back after all. Maybe I also forgot to mention that my service is a WCF service .NET4. Googled and guess what. I had to add the crossDomainScriptAccessEnabled="true" option in my web.config:

<bindings>
  <webHttpBinding>
    <binding name="webHttpBindingWithJsonP" crossDomainScriptAccessEnabled="true" />
  </webHttpBinding>
</bindings>

Appaerently it's what is needed for WCF to work with jsonp.

I found the explanation on the following link

Thanks.

Upvotes: 0

donramos
donramos

Reputation: 534

JSONP works by appending the response to the DOM. During a JSONP call, JQuery automatically adds a "callback" parameter in the GET call. Your service must then return the result wrapped with the callback function, in the format:

callback(<jsondata>)

Here's a simple PHP example (in prod, add callback name validations):

// .. prepare result

$callback = $_GET['callback'];
echo $callback.'('. json_encode($result).  ');'; ?>

Also, your use of "bind" is faulty too since passing "data" to it will only give the first record to "displayNews". Simplify it by calling functions directly:

success: function (news, textStatus, xhr) {
      displayNews(news);
      $("#itemCount").text(news.length);
      if (callback) callback(news);
}

Finally, change your displayNews to iterate over the list:

  function displayNews(news) {
        var newsList = $("#hackerNews").find(".newsList");
        newsList.empty();
        $.each(news, function(k,v) {
         $("#newsItem").tmpl(v).appendTo(newsList).trigger("create");
    });
    newsList.listview("refresh");
  }

Upvotes: 1

Twisty
Twisty

Reputation: 30893

I find I get better results when I define the type settings. Example:

$.ajax({
    url: "http://localhost:31634/expertREST.svc/GetKnowledgeFields",
    type: 'GET',
    dataType: "jsonp",
    success: function (data, textStatus, xhr) {
        $this.trigger("news.updated", data);
        if (callback) callback(data);
    }
 });

I would also advise setting async to false, yet I see this is not supported by jsonp:

Cross-domain requests and dataType: "jsonp" requests do not support synchronous operation.

Edit: error can't be used, that's not very helpful.

Note: This handler is not called for cross-domain script and JSONP requests. This is an Ajax Event.

Not sure how you can trouble shoot this further.

Upvotes: 1

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