RE: [Wicket-user] Question about DataTable and IDataProvider restated

[Frank Silbermann]

I suppose the usual approach is to trigger the download of IDataProvider’s data via the event handler of the submit button.  That way, the data would be available for both “Iterator IDataProvider.iterate(first, count)” and “int IDataProvider.size()”.   However, I do not have a single submit button – I have various sets of radio-buttons and a change to any one causes an immediate postback.  I do not want to code an event handler for each one of them; I’d rather put my database query in a method that is called before the page is rendered _regardless_ of the reason.  Can you suggest a suitable method?   I tried putting the database query in “Iterator IDataProvider.iterate(first, count)” but that doesn’t seem to work, perhaps because it comes too late for “int IDataProvider.size()” to have the information.  Putting the database query in “int IDataProvider.size()” may simply reverse the problem.   Into which method _should_ I place the database query?  What are my options?       -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Frank Silbermann Sent: Tuesday, April 04, 2006 3:33 PM To: wicket-user@lists.sourceforge.net Subject: RE: [Wicket-user] ?Contract for "Iterator IDataProvider.iterator(int first, int count)" ???   I have a question about the intended use of the DataTable components provided in Wicket Extensions.  The DataTable relies upon an IDataProvider to provide the data.  To do this, we implement: “Iterator iterate(first, count)” Lacking any advice to the contrary, I assumed that this is the method which would retrieve data from the database, but this does not seem to be working well for me. My database query is parameterized based on page-component model values, and these may change with each rendering. My problem is that when one rendering presents a short data set, on the next rendering the DataTable is not always requesting all of the rows.  The “count” seems to be affected by the number of rows returned by the previous rendering. I suspect this is because my implementation of  “int DataProvider.size()” assumes that it will be called _after_ “Iterator iterate(first, count)” pulls down the data – so it’s always one rendering behind. Should I give the “int IDataProvider.size()” method the responsibility for figuring out the query string and going to the database?  (How else would it be able to tell the DataProvider how many rows to request?)