Catalin Kormos wrote:
Looks to me like there a few things that need to be changed when sorting
is involved also. For now I found the following, it works for me now,
but its possible that i'm wrong, please correct me if I am:
- the dataset size needs to be fetched independently from the actual data
Yes. You need to do a select count(*) operation to determine the actual
number of available rows before fetching the subset of data wanted.
There's no way a scroller component can render itself without knowing
the full size of the dataset.
- the t:dataTable should preserve the sorting and the dataModel.
The first one I needed, because I was asking for the row count before
the table is rendered, and the second one its not realy clear to me why
is needed, I mean why the "preserveDataModel" should be "true", it works
only like this.
I wouldn't think that preserveDataModel would work at all with this
approach. This caches the displayed data, which is exactly what you
*don't* want to do when you've only got part of the available data
loaded into memory.
I don't know why you're having problems with the sorting; there's
nothign very complex here:
<t:dataTable
sortColumn="#{myBean.sortColumn}"
sortAscending="#{myBean.sortAscending}"
value="#{myBean.myDataModel}">
public class myBean {
// add getters and setters for sortColumn, sortAscending
public DataModel getMyDataModel() {
// as per wiki page
}
public DataPage getDataPage(int startRow, int pageSize) {
// build sql where-clause to select desired rows of data
// prefix query with "select count(*) from xx where ...."
// then execute this to get the number of available rows
// create the select statement using where-clause
// add "sort by xxxx" depending on value of this.sortColumn
// add "ASC" or "DESC" depending on value of this.sortAscending
// add code to select just the set of desired rows
// execute the query to get the actual rows, in the desired order
// create a DataPage object to wrap size+data info, and return it.
}
}
