public interface ClientOnlyDataSources

Client Only DataSources

For prototyping purposes, a "client-only" DataSource can be created that has no permanent storage and never contacts the server, instead using a set of test data to respond to requests in the same manner as a server-based DataSource might.

The client-side interface to a client-only DataSource is identical to a server-based DataSource, including asynchronous responses, so that a client-only DataSource can be replaced by a server-based DataSource without code changes. The only difference is that changes to records belonging to the DataSource persist only until the page is reloaded.

Client-only DataSources allow you to create a complete prototype application in an .html file that does not require a server.

The setClientOnly method is specified to create a client-only DataSource. For example:

   DataSource dataSource = new DataSource();
   dataSource.setID("stockQuotesDS");
   DataSourceField idField = new DataSourceField("id", FieldType.INTEGER, "Id");
   ........
   dataSource.setFields(idField,.....);
   dataSource.setClientOnly(true);

If you have existing test data in XML (see the Admin Console for expected format), you can load it into a client-only DataSource using setDataURL method, like so:

   DataSource dataSource = new DataSource();
   dataSource.setID("stockQuotesDS");
   dataSource.setRecordXPath("/List/stockQuotes");
   DataSourceField idField = new DataSourceField("id", FieldType.INTEGER, "Id");
   ........
   dataSource.setFields(idField,.....);
   dataSource.setDataURL("ds/test_data/stockQuotes.data.xml");
   dataSource.setClientOnly(true);

The DataSource will lazily make a one-time fetch against the specified data file the first time an operation is called on it. From then on, the DataSource will work against the local cache created from this initial request. This is a quick way to prototype against some test data that may eventually be returned from an arbitrary back-end.

Finally, it is possible to have a DataSource which initially fetches the entire dataset and performs all subsequent fetching locally, while still visiting the server to perform all other operations. See DataSource.cacheAllData.

See Also:

DataSource.getClientOnly()

Interface ClientOnlyDataSources

Client Only DataSources