ExportData - Custom rendering - Pagination

[jperin]

Hi Isomorphic,

I have succeed to export data from a ListGrid in csv, and applying a custom rendering on columns. This export is returning to the client for "Download".

I would like to know if is it possible to do this with a sort a pagination. This to avoid having memory error / performance leak on the server.

The way I call the export :

final DSRequest dsRequestProperties = new DSRequest();
dsRequestProperties.setExportAs("csv");
dsRequestProperties.setExportDisplay(ExportDisplay.DOWNLOAD);
dsRequestProperties.setExportDatesAsFormattedString(true);
dsRequestProperties.setOperationId("export");
dsRequestProperties.setOperationType(DSOperationType.FETCH);

grid.exportData(dsRequestProperties);

This export will call a specific method to customize the data

<operationBinding operationType="fetch" operationId="export" dropExtraFields="false">
	<serverObject lookupStyle="new" className="com.server.dmi.BaseServerObject" methodName="exportCustomers"/>
</operationBinding>

public DSResponse exportCustomers(DSRequest dsRequest, HttpServletRequest servletRequest) throws Exception {
	DataSource dataSource = DataSourceManager.get("dataSource"));
	Map criteria = dsRequest.getCriteria();

	DSRequest pagRequest = new DSRequest();
	pagRequest.setDataSource(dataSource);
	pagRequest.setCriteria(criteria);
	pagRequest.setOperationType("fetch");

	final DSResponse pagResponse = pagRequest.execute();
	List<Map<String, Object>> datas = (List<Map<String, Object>>)pagResponse.getData();
	for (Map<String, Object> data : datas) {
		data.put("CLASSIFICATION",Localization.translate(servletRequest.getLocale(),(String)data.get("CLASSIFICATION")));
	}
	return pagResponse;
}

What I try to do is to have a pagination in the pagRequest.execute() that will return a set of the date to export, and a way to specify to the exportData that the data returned in the response is paginated and the method must be recall.

Is there a way to do this?

Regards

Julien

[Isomorphic]

Setting dsRequest.streamResults results in a streaming export when you use SQLDataSource, but this is of course only possible if you don't implement a DMI that explicitly iterates through all the records.

In 5.0, there are new server-side APIs you can implement (DSResponse.hasNextRecord() and nextRecordAsObject()) to implement a streaming export with custom logic like you've shown. You would return a subclass of DSResponse where you have implemented hasNextRecord() and nextRecordAsObject() to call the same APIs on the original DSResponse, but modify the result before returning it.

[jperin]

Ok I can use a SQLDataSource, but how can I execute an operation on each record.
Is the query will be paginated?

[Isomorphic]

? We just answered that:

In 5.0, there are new server-side APIs you can implement (DSResponse.hasNextRecord() and nextRecordAsObject()) to implement a streaming export with custom logic like you've shown. You would return a subclass of DSResponse where you have implemented hasNextRecord() and nextRecordAsObject() to call the same APIs on the original DSResponse, but modify the result before returning it.