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Breadcrumbs go here --> <li>QML Global Object</li> </ul> </div> <div class="toolbuttons toolblock"> <ul> <li id="smallA" class="t_button">A</li> <li id="medA" class="t_button active">A</li> <li id="bigA" class="t_button">A</li> <li id="print" class="t_button"><a href="javascript:this.print();"> <span>Print</span></a></li> </ul> </div> </div> <div class="content mainContent"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#qt-object">Qt Object</a></li> <li class="level1"><a href="#xmlhttprequest">XMLHttpRequest</a></li> <li class="level1"><a href="#offline-storage-api">Offline Storage API</a></li> <li class="level2"><a href="#database-api">Database API</a></li> <li class="level3"><a href="#db-opendatabasesync-identifier-version-description-estimated-size-callback-db">db = openDatabaseSync(identifier, version, description, estimated_size, callback(db))</a></li> <li class="level3"><a href="#db-changeversion-from-to-callback-tx">db.changeVersion(from, to, callback(tx))</a></li> <li class="level3"><a href="#db-transaction-callback-tx">db.transaction(callback(tx))</a></li> <li class="level3"><a href="#db-readtransaction-callback-tx">db.readTransaction(callback(tx))</a></li> <li class="level3"><a href="#results-tx-executesql-statement-values">results = tx.executeSql(statement, values)</a></li> <li class="level1"><a href="#logging">Logging</a></li> </ul> </div> <h1 class="title">QML Global Object</h1> <span class="subtitle"></span> <!-- $$$qdeclarativeglobalobject.html-description --> <div class="descr"> <a name="details"></a> <p>Contains all the properties of the JavaScript global object, plus:</p> <a name="qt-object"></a> <h2>Qt Object</h2> <p>The <a href="qml-qt.html#qmlglobalqtobject">Qt object</a> provides useful enums and functions from Qt, for use in all QML files.</p> <a name="xmlhttprequest"></a> <h2>XMLHttpRequest</h2> <a name="xmlhttprequest"></a><p>QML script supports the <a href="#xmlhttprequest">XMLHttpRequest</a> object, which can be used to asynchronously obtain data from over a network.</p> <p>The <a href="#xmlhttprequest">XMLHttpRequest</a> API implements the same <a href="http://www.w3.org/TR/XMLHttpRequest/">W3C standard</a> as many popular web browsers with following exceptions:</p> <ul> <li>QML's <a href="#xmlhttprequest">XMLHttpRequest</a> does not enforce the same origin policy.</li> <li>QML's <a href="#xmlhttprequest">XMLHttpRequest</a> does not support <i>synchronous</i> requests.</li> </ul> <p>Additionally, the <tt>responseXML</tt> XML DOM tree currently supported by QML is a reduced subset of the <a href="http://www.w3.org/TR/DOM-Level-3-Core/">DOM Level 3 Core</a> API supported in a web browser. The following objects and properties are supported by the QML implementation:</p> <table class="generic"> <thead><tr class="qt-style"><th ><b>Node</b></th><th ><b>Document</b></th><th ><b>Element</b></th><th ><b>Attr</b></th><th ><b>CharacterData</b></th><th ><b>Text</b></th></tr></thead> <tr valign="top" class="odd"><td ><ul> <li>nodeName</li> <li>nodeValue</li> <li>nodeType</li> <li>parentNode</li> <li>childNodes</li> <li>firstChild</li> <li>lastChild</li> <li>previousSibling</li> <li>nextSibling</li> <li>attributes</li> </ul> </td><td ><ul> <li>xmlVersion</li> <li>xmlEncoding</li> <li>xmlStandalone</li> <li>documentElement</li> </ul> </td><td ><ul> <li>tagName</li> </ul> </td><td ><ul> <li>name</li> <li>value</li> <li>ownerElement</li> </ul> </td><td ><ul> <li>data</li> <li>length</li> </ul> </td><td ><ul> <li>isElementContentWhitespace</li> <li>wholeText</li> </ul> </td></tr> </table> <p>The <a href="declarative-xml-xmlhttprequest.html">XMLHttpRequest example</a> demonstrates how to use the <a href="#xmlhttprequest">XMLHttpRequest</a> object to make a request and read the response headers.</p> <a name="offline-storage-api"></a> <h2>Offline Storage API</h2> <a name="database-api"></a> <h3>Database API</h3> <p>The <tt>openDatabaseSync()</tt> and related functions provide the ability to access local offline storage in an SQL database.</p> <p>These databases are user-specific and QML-specific, but accessible to all QML applications. They are stored in the <tt>Databases</tt> subdirectory of <a href="qdeclarativeengine.html#offlineStoragePath-prop">QDeclarativeEngine::offlineStoragePath</a>(), currently as SQLite databases.</p> <p>The API can be used from JavaScript functions in your QML:</p> <pre class="qml"></pre> <p>The API conforms to the Synchronous API of the HTML5 Web Database API, <a href="http://www.w3.org/TR/2009/WD-webdatabase-20091029/">W3C Working Draft 29 October 2009</a>.</p> <p>The <a href="declarative-sqllocalstorage.html">SQL Local Storage example</a> demonstrates the basics of using the Offline Storage API.</p> <a name="db-opendatabasesync-identifier-version-description-estimated-size-callback-db"></a> <h4>db = openDatabaseSync(identifier, version, description, estimated_size, callback(db))</h4> <p>Returns the database identified by <i>identifier</i>. If the database does not already exist, it is created, and the function <i>callback</i> is called with the database as a parameter. <i>description</i> and <i>estimated_size</i> are written to the INI file (described below), but are otherwise currently unused.</p> <p>May throw exception with code property SQLException.DATABASE_ERR, or SQLException.VERSION_ERR.</p> <p>When a database is first created, an INI file is also created specifying its characteristics:</p> <table class="generic"> <thead><tr class="qt-style"><th ><b>Key</b></th><th ><b>Value</b></th></tr></thead> <tr valign="top" class="odd"><td >Name</td><td >The name of the database passed to <tt>openDatabase()</tt></td></tr> <tr valign="top" class="even"><td >Version</td><td >The version of the database passed to <tt>openDatabase()</tt></td></tr> <tr valign="top" class="odd"><td >Description</td><td >The description of the database passed to <tt>openDatabase()</tt></td></tr> <tr valign="top" class="even"><td >EstimatedSize</td><td >The estimated size (in bytes) of the database passed to <tt>openDatabase()</tt></td></tr> <tr valign="top" class="odd"><td >Driver</td><td >Currently "QSQLITE"</td></tr> </table> <p>This data can be used by application tools.</p> <a name="db-changeversion-from-to-callback-tx"></a> <h4>db.changeVersion(from, to, callback(tx))</h4> <p>This method allows you to perform a <i>Scheme Upgrade</i>.</p> <p>If the current version of <i>db</i> is not <i>from</i>, then an exception is thrown.</p> <p>Otherwise, a database transaction is created and passed to <i>callback</i>. In this function, you can call <i>executeSql</i> on <i>tx</i> to upgrade the database.</p> <p>May throw exception with code property SQLException.DATABASE_ERR or SQLException.UNKNOWN_ERR.</p> <a name="db-transaction-callback-tx"></a> <h4>db.transaction(callback(tx))</h4> <p>This method creates a read/write transaction and passed to <i>callback</i>. In this function, you can call <i>executeSql</i> on <i>tx</i> to read and modify the database.</p> <p>If the callback throws exceptions, the transaction is rolled back.</p> <a name="db-readtransaction-callback-tx"></a> <h4>db.readTransaction(callback(tx))</h4> <p>This method creates a read-only transaction and passed to <i>callback</i>. In this function, you can call <i>executeSql</i> on <i>tx</i> to read the database (with SELECT statements).</p> <a name="results-tx-executesql-statement-values"></a> <h4>results = tx.executeSql(statement, values)</h4> <p>This method executes a SQL <i>statement</i>, binding the list of <i>values</i> to SQL positional parameters ("?").</p> <p>It returns a results object, with the following properties:</p> <table class="generic"> <thead><tr class="qt-style"><th ><b>Type</b></th><th ><b>Property</b></th><th ><b>Value</b></th><th ><b>Applicability</b></th></tr></thead> <tr valign="top" class="odd"><td >int</td><td >rows.length</td><td >The number of rows in the result</td><td >SELECT</td></tr> <tr valign="top" class="even"><td >var</td><td >rows.item(i)</td><td >Function that returns row <i>i</i> of the result</td><td >SELECT</td></tr> <tr valign="top" class="odd"><td >int</td><td >rowsAffected</td><td >The number of rows affected by a modification</td><td >UPDATE, DELETE</td></tr> <tr valign="top" class="even"><td >string</td><td >insertId</td><td >The id of the row inserted</td><td >INSERT</td></tr> </table> <p>May throw exception with code property SQLException.DATABASE_ERR, SQLException.SYNTAX_ERR, or SQLException.UNKNOWN_ERR.</p> <a name="logging"></a> <h2>Logging</h2> <p><tt>console.log()</tt> and <tt>console.debug()</tt> can be used to print information to the console. 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