Re: [T5] GridDataSource: why call getAvailableRows before prepare?

[Jux <ju...@hot.ee>]

I have the exact same problem/question?
When I call prepare myself and update my "availableRows" parameter. Once the
getAvailableRows run, the parameter is reseted by itself. How to use
GridDatasource the correct way?



Franz Amador wrote:
> 
> I'm starting to use Grid to display the paged, sortable results of a
> Hibernate query, so I'm implementing GridDataSource.  I was dismayed to
> see that getAvailableRows gets called before prepare.  This means that I
> have to run my query twice: once to count the total rows (when
> getAvailableRows gets called), and again to do the sorting and get the
> correct page (when prepare gets called).
> 
> If, instead, prepare got called first, then I could do the sorting and
> page extraction and get the total number of results all in one query (just
> add "count(*)" to the columns being returned).  You might ask, how can the
> system know the page size to ask for when calling prepare if it hasn't
> called getAvailableRows first?  No problem: just ask for the first full
> page and have prepare return the number of rows it actually found.  (Or
> add a getter for that information.)
> 
> For fast queries, running them twice isn't that great a sin, but for slow
> queries, such as in a user-specified search page, running them twice when
> you don't really have to seems extravagant to me.
> 

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