paging on listgrid

[pdagaonk]

Using smartgwt 2.5. Opened in firefox 7.0

Hi i tried to use the paging capability on list grid.
I tried with setting the page size as very small
articleListRender.setDataPageSize(3);
However i found the list grid still loads all records instead of just loading 3.

This is the way we call fetch data.

articleListRender.fetchData(c, new DSCallback() {

@Override
public void execute(DSResponse response, Object rawData, DSRequest request) {
System.out.println("after fetch, start:" + response.getStartRow() + ", end:" + response.getEndRow() + ", total:" + response.getTotalRows());

}
});

The print out shows the response contains 4 hundreds records.

Is there anything we could miss?

Thanks

[Isomorphic]

There are a number of settings that force a fetch of all rows, such as showAllRecords:true, dataFetchMode:"basic", or auto-sizing settings like autoFitData.

[pdagaonk]

Hi thank you for the reply.

I found that we need to do some handling in DMI too. (make it not always returning all the records)

However i found the grid won't keep fetching data on the demand when i scroll down.

I referenced this example http://www.smartclient.com/smartgwt/showcase/#grid_adaptive_filter_featured_category

It is also not setting anything else. Is there any way i can enable the paging on scrolling behavior?

Thanks

[Isomorphic]

All you have to do is return correct values for startRow, endRow and totalRows. You can use the RPC tab of the Developer Console to see what you've returned.

[pdagaonk]

Hi,

Thank you for the reply.
Do u mean i don't need to do anything from DMI such as only getting a certain range of records?

Instead just setting those properties in DSResponse when returning from executeFetch?

Thanks

[Isomorphic]

You need to return a DSResponse containing your data as the data, and correct settings for startRow, endRow and totalRows.

[pdagaonk]

Hi,

Thank you again for the reply.

Here is my code in the server side

public DSResponse executeFetch(DSRequest req) throws Exception {
List records = fetchRecords(req.getCriteria(), req);
DSResponse response = new DSResponse(records);
response.setStartRow(req.getStartRow());
response.setEndRow(req.getEndRow());
response.setTotalRows(records.size());
return new DSResponse(records);
}

Here is my fetch in the client side
articleListRender.fetchData(c, new DSCallback() {

@Override
public void execute(DSResponse response, Object rawData, DSRequest request) {
String preViewState = preference.get(Integer.toString(subjectQueryID));
System.out.println("request- start:" + request.getStartRow() + ", end:" + request.getEndRow());
System.out.println("response- start:" + response.getStartRow() + ", end:" + response.getEndRow());

}
});


The print shows
request- start:0, end:75
response- start:0, end:472

Although the request ranges from 0 to 72, however response has begin to end from 0 to 472.

Did i set it wrong in the server?

Thanks

[Isomorphic]

Yes, you set it wrong. You are returning all the rows.

[pdagaonk]

Hi,

ok. in my example, i am asking for row 0 to 75 in my request. The total results that will meet the criteria is 472.

So in DSResponse, do i set start row as 0, end row as 75, total row as 472 but only supply real data from 0 to 75? Which mean when doing this
return new DSResponse(records)
the records only contain 75 rows?

Thanks

[Isomorphic]

Correct. This will enable paging.

Then, for performance, you should find a way to avoid fetching all 472 records in your DMI. All the built-in connectors for SQL, Hibernate, etc do this by requesting specific row ranges from the underlying database.

[pdagaonk]

It works.
Thank you very much for your help :)

[stonebranch1]

What I am uncertain about is what to return for total rows on subsequent paged fetch requests?

Lets say I have 250 rows and my request size is 100. In my custom datasource the first fetch via DMI requests startRow=0 and endRow=100 and since I can detect this is the 1st fetch I do a count and return back startRow=0, endRow=100, totalRows=250. All good.

Upon scrolling in the list grid the next request comes in with startRow=100, endRow=200. I fetch the requested 100 rows and return back startRow=100, endRow=200 but what should I set for the value of total rows? I avoid doing a count here since we are paging so I don't know the total rows.

How should I be handling this?

Thanks

[Isomorphic]

Return the correct totalRows number. This may indeed involve doing a "count" request against, but you need to do so in case the dataset is modified, otherwise, you could be returning data that doesn't agree in row numbering with previously returned data.