How do you add a new attribute to a dataset node in OpenLaszlo platform?

Question

如何在OpenLaszlo XML数据集中的节点上添加全新属性？

Answer 1

The way to do this is to use the lz.datapointer.setNodeAttribute() function. If you use the setNodeAttribute() function with an attribute name that does not already appear on the node, a new one will be created.

In the sample OpenLaszlo application below, if you press the button titled [displayXML] after you compile the program, you will see the XML dataset before any changes are made does not contain any "fav_saying" attribute.

After you click the [updateAttribute] button to add the favorite saying for Homer via the setNodeAttribute() method, you can then click the [displayXML] button again and you will see that an attribute called 'fav_saying' has been added to the XML dataset.

<canvas height="665" width="1000" layout="axis: x" debug="true">

<dataset name="myData">
<myXML>
<person firstname="Homer" lastname="Simpson" />
<person firstname="Marge" lastname="Simpson" />
<person firstname="Montgomery" lastname="Burns" />
</myXML>
</dataset>

<button text="displayXML">

<handler name="onclick">
  Debug.write(canvas.myData.serialize());
</handler>

</button>

<button text="updateAttribute">

<handler name="onclick">  

  var dp = canvas.myData.getPointer(); // get datapointer to XML data
  dp.setXPath('myXML/person[@firstname="Homer"]'); // set xpath to Homer Simpson

  dp.setNodeAttribute('fav_saying', 'DOH!');

</handler>

</button>

</canvas>

You will also see that multiple calls to setNodeAttribute() will not add additional 'fav_saying' attributes. If the program used a different value for the saying every time then the value in the 'fav_saying' attribute would change but there would still only be one 'fav_saying' attribute.