Storing settings in Symbian Web Runtime

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This code snippet demonstrates how to save persistent data and then restore it when restarting the application by using the methods widget.setPreferenceForKey() and widget.preferenceForKey(), respectively.

Article Metadata

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Code Example

Source file: Media:SavingPersistentData.diff.zip Media:Storing settings in WRT.zip

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Tested with

Devices(s): Nokia 5800 XpressMusic

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Compatibility

Platform(s): S60 3rd Edition FP2, S60 5th Edition

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Article

Keywords: widget.setPreferenceForKey(), widget.preferenceForKey()

Created: MiGryz (26 Feb 2009)

Last edited: hamishwillee (05 Oct 2012)

Source: Relevant HTML components

<div id="bodyContent" class="bodyContent">
    <label for="txt">Text:</label>
    <input id="txt" type="text"></input>
    <input type="button" onclick="saveString();" value="Save" />
</div>

Source

// Initializes the widget
function init() {
    // ...
 
    // Loads the saved string into the input field if the key exists
    var savedString = widget.preferenceForKey("key");
    if (savedString != null) {
        document.getElementById("txt").value = savedString;
    }
}
 
// Saves the string from the input field to persistent storage.
function saveString( ) {
    widget.setPreferenceForKey(document.getElementById("txt").value, "key");
    alert("String saved.");
}

Postconditions

Upon loading, text that corresponds to key in the persistent storage is displayed. You can change the text and use the Save button to save it. It will be restored the next time the widget is launched.

Supplementary material

This code snippet is part of the stub concept, which means that it has been patched on top of a template application in order to be more useful to developers. The version of the WRT stub application used as a template in this snippet is v1.1.

• The patched, executable application that can be used to test the features described in this snippet is available for download at Media:Storing settings in WRT.zip.
• You can view all the changes that are required to implement the above-mentioned features. The changes are provided in unified diff and colour-coded diff (HTML) formats in Media:SavingPersistentData.diff.zip.
• For general information on applying the patch, see Using Diffs.
• For unpatched stub applications, see Example app stubs with logging framework.