[Laszlo-dev] For Review: Change 20071105-jcrowley-a Summary: Find source of basedatacombobox-based components

[J Crowley]

Change 20071105-jcrowley-a by jcrowley at DoctorManhattan.mshome.net on  
2007-11-05 14:07:01 EST
     in /Users/jcrowley/src/svn/openlaszlo/trunk-g
     for http://svn.openlaszlo.org/openlaszlo/trunk

Summary: Find source of basedatacombobox-based components
	with selectfirst="false" emits Debugger warnings

New Features:

Bugs Fixed: LPP-4704 : Find source of basedatacombobox-based
	components with selectfirst="false" emits Debugger
	warnings

Technical Reviewer: henry
QA Reviewer: max
Doc Reviewer: (pending)

Documentation:

Release Notes:

Details: This is a workaround for an issue involving
	xpathQuery() calls from an oninit handler.
	Basedatacombobox kept getting "p is null"
	warnings because it was requesting data
	before the data was actually there, and because
	it doesn't itself have a datapath, but rather
	string attributes like "itemdatapath" that it
	uses in xpathQuery() calls, I couldn't just
	move things from oninit to ondata.

	My solution, then, was to add a private
	datapointer. The basedatacombobox sets the
	datapointer's xpath to the first node of
	itemdatapath, so that it's listening for at
	least the initial data call.  The ondata
	handler for this datapointer then makes the
	calls to the method that has the various
	xpathQuery() calls that had been getting called
	too early.

	The "p is null" errors are expected in
	situations where calls like this are made, but
	we shouldn't be generating them from our own
	base components.

	I'm not sure if this is the best possible
	solution, necessarily, but it fixes the
	issues while not seeming to break anything.

Tests: The example attached to the bug.  Notice there
	are no "p is null" warnings.  (You can compare
	with an unmodified branch, if you'd like.)

	Also, run:
	test/components/base/lzunit-basedatacombobox.lzx

	It operates as before, minus the "p is null"
	warnings.

Files:
M      lps/components/base/basedatacombobox.lzx

Changeset: http://svn.openlaszlo.org/openlaszlo/patches/20071105-jcrowley-a.tar