I was working with a friend today who had an interesting question. How do you preselect a row in a Spry Dataset? Turns out this was pretty simple (at first).

The initial solution is to simply add an "observer" to the dataset. You can think of this as a watcher. He will sit there until a certain event (the one he cares about) is fired. At that point he will then execute custom code. There are a set of default events you can observe:

onPreLoad, onPostLoad, onLoadError, onDataChanged, onPreSort, onPostSort, onCurrentRowChanged.

You can find details about these by scrolling down to "Observer Notifications" on the Spry documentation page.

So obviously onPostLoad will do it for you. Let's take a look at an example:

In this example I created a function within a JavaScript object named myObserver. This is tied to a dataset named entries. My preselect value is 1 and hard coded, but obviously it could be dynamic:

Remember that dataset rows start with 0. (Who else thinks ten million years from now we will still be starting arrays with 0 instead of 1??) Next we get the ID of the row we want:

And then lastly we use that ID to set the current selected row:

So this works like a charm.... almost. My friend was using a select box. I needed to preselect that as well. That's simple, right?

However when I ran this, the dropdown went away completely! Turns out my observer was running when the data was loaded. This was expected. But it was firing before Spry had a chance to actually update the HTML!

Luckily there is another way of handling it. Instead of watching over the dataset, we simply observe the region! I've blogged about region notifications before, using the simpler format of div's with state values. You can also write custom JavaScript code as well. Consider this new example:

This code is pretty similar, except that I use the Spry.Data.Region.addObserver function to assign the observer code to the region. Thanks go to Kin Blas of Adobe for the help with this.