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File in Windows Store Apps

Posted by Deepak Arora Articles | Windows Store Apps November 01, 2012
In this app I described how store data in a file in roaming folder in a Windows Store App using JavaScript.
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Introduction

In this article I describe how to create a Windows Store App for storing data in a file in roaming folder using JavaScript. User data in an app can be stored as files. There are three locations available for storing files; they are:

  1. Windows.Storage.ApplicationData.current.localFolder
  2. Windows.Storage.ApplicationData.current.roamingFolder
  3. Windows.Storage.ApplicationData.current.temporaryFolder.
I assume you can create a simple Windows Store App using JavaScript. For more help visit Simple Windows Store Apps using JavaScript.

To start the creation of the app, add one JavaScript page by right-clicking on the js folder in the Solution Explorer and select Add > new item > JavaScript Page and then give an appropriate name. In the same way, add one HTML page to your project.

files-in-windows-store-apps.jpg

Write the following code in default.html:

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8" />

    <title>App</title>

    <link rel="stylesheet" href="//Microsoft.WinJS.1.0/css/ui-light.css" />

    <script src="//Microsoft.WinJS.1.0/js/base.js"></script>

    <script src="//Microsoft.WinJS.1.0/js/ui.js"></script>

    <link rel="stylesheet" href="/css/default.css" />

    <script src="/js/default.js"></script>

</head>

<body role="application" style="background-color: lightyellow">

    <center><div id="rootGrid">

         <div id="content">

            <h1 id="featureLabel"></h1>

            <div id="contentHost"></div>

        </div>

          </div></center>

</body>

</html>

Write the following code in default.js:
 

(function () {

    "use strict";

    var appTitle = "";

    var pages = [

        { url: "page.html", title: "SetVersion" }

    ];

    function activated(eventObject) {

        if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) {

            eventObject.setPromise(WinJS.UI.processAll().then(function () {

                var url = WinJS.Application.sessionState.lastUrl || pages[0].url;

                return WinJS.Navigation.navigate(url);

            }));

        }

    }

 

    WinJS.Navigation.addEventListener("navigated", function (eventObject) {

        var url = eventObject.detail.location;

        var host = document.getElementById("contentHost");

        host.winControl && host.winControl.unload && host.winControl.unload();

        WinJS.Utilities.empty(host);

        eventObject.detail.setPromise(WinJS.UI.Pages.render(url, host, eventObject.detail.state).then(function () {

            WinJS.Application.sessionState.lastUrl = url;

        }));

    });

    WinJS.Namespace.define("App", {

        appTitle: appTitle,

        pages: pages

    });

    WinJS.Application.addEventListener("activated", activated, false);

    WinJS.Application.start();

})();

Write the following code in page.html:

<!
DOCTYPE html>

<html>

<head>

    <title></title>

    <link rel="stylesheet" href="/css/default.css" />

    <script src="/js/script.js"></script>

</head>

<body>

    <div data-win-control="App.pageInput">

        <button class="action" id="filesIncrement">Create File</button>

    </div>

    <div data-win-control="App.pageOutput">

        <div class="item" id="filesOutput"></div>

    </div>

</body>

</html>


Write the following code in script.html:

(
function () {

    "use strict";

    var page = WinJS.UI.Pages.define("page.html", {

        ready: function (element, options) {

            document.getElementById("filesIncrement").addEventListener("click", filesIncrement, false);

            filesDisplayOutput();

        }

    });

    var roamingFolder = Windows.Storage.ApplicationData.current.roamingFolder;

    var filename = "appFile.txt";

    var counter = 0;

    function filesIncrement() {

        counter = counter + 1;

 

        roamingFolder.createFileAsync(filename, Windows.Storage.CreationCollisionOption.replaceExisting)

            .then(function (file) {

                return Windows.Storage.FileIO.writeTextAsync(file, counter);

            }).done(function () {

                filesDisplayOutput();

            });

    }

    function filesReadCounter() {

        roamingFolder.getFileAsync(filename)

            .then(function (file) {

                return Windows.Storage.FileIO.readTextAsync(file);

            }).done(function (text) {

                counter = parseInt(text);

                document.getElementById("filesOutput").innerText = "file: " + counter;

            }, function () {

                document.getElementById("filesOutput").innerText = "file: <not found>";

            });

    }

    function filesDisplayOutput() {

        filesReadCounter();

    }

})();


Output:

files-in-windows-store-app.jpg

Summary


In this app I described how to store data in a file in a roaming folder in a Windows Store App using JavaScript. I hope this article has helped you to understand this topic. Please share if you know more about this. Your feedback and constructive contributions are welcome.

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