Hi,
I'm not being very clear, sorry. Basically, all I want is to have my
charts update automatically. As you know, there's 2 methods talking to
each other here:
Client: Query.send(callback)
Servlet: generateTable(query, request)
The generateTable sends a DataTable back to the callback correctly the
first time. But nothing happens after this. Regardless of whether or
not the DataTable produced by generateTable has changed, I would still
expect the generateTable method to be called at the
query.setRefreshInterval (5 seconds).
I must be doing something wrong, because I can't see how the
query.send can poll if the DataTable has changed, since generateTable
is just a stupid method that returns a DataTable object whenever it is
called.
I don't even mind if the full dataTable is sent back to the callback
every 5 seconds, I just want to see that it updates in realtime.
Here are the important parts of my code:
Servlet:
public class FetchDataTable extends DataSourceServlet{
@Override
public DataTable generateDataTable(Query query, HttpServletRequest
request) throws DataSourceException {
System.out.println("DataTableGenerator: [" + new Date() + "] -
" + request.getRequestURL() + " - " + request.getQueryString());
DataTable dataTable = generator.buildDataTableFromDB();
return dataTable;
}
...
}
Client:
final Runnable onLoadCallback = new Runnable() {
public void run() {
final Visualization chart = ChartManager.buildChart
(chartType, width, height, title);
wrapper.addChild(chart);
Query query = Query.create("http://localhost:8084/
FetchDataTable?tqx=reqId:" + (Math.random() * 1000000)));
query.setRefreshInterval(5);
query.send(new Callback(){
public void onResponse(QueryResponse response) {
if (response.isError())
SC.say("An error occured: " +
response.getDetailedMessage());
else
{
chart.draw(response.getDataTable
(),ChartOptions.create(chartType, width, height, title));
wrapper.unmask();
}
}
});
}
};
// Load the visualization api, passing the onLoadCallback to
be called when loading is done.
ChartOnlineAPI.loadAPI(chartType, onLoadCallback);
On Aug 13, 10:17 am, VizWiz <[email protected]> wrote:
> Hi,
>
> I am not sure why you would like to change this behavior, however, there is
> currently no api for changing it.
>
> The code that handles this is in JsonRenderer.renderJsonResponse (lines
> 120-128). It is open source, so you can change it as you like for your own
> use and as long as it is in the confines of the code license.
>
> Cheers,
> VizWiz.
>
> On Thu, Aug 13, 2009 at 9:46 AM, Hazer <[email protected]> wrote:
>
> > I see. Thanks for that, so there must be code in the servlet which
> > handles this "hasTheDataChanged" query.
>
> > I have a Servlet which extends DataSourceServlet, so it only
> > implements one method: generateTable. This method builds a dataTable
> > object from a db backend. Is there another method I should be
> > overriding to get the desired effect of a servlet response which says
> > "Yes, the data has changed" or "No, the data is the same".
>
> > Thanks very much for your help.
>
> > On Aug 11, 1:33 pm, MC Get Vizzy <[email protected]> wrote:
> > > On Tue, Aug 11, 2009 at 12:56 PM, Hazer <[email protected]> wrote:
>
> > > > Hi, thanks for the response.
>
> > > > But when you ask "has the underlying data changed", do you mean the
> > > > remote dataTable to be fetched? How could the client know if the data
> > > > has changed without sending the query at the refresh interval? Is
> > > > there some sort of implicit "hasDataChanged" request sent before
> > > > query.send is fired??
>
> > > the data source is queried, and if the data source responds that the
> > > underlying data has not changed, your callback is not called.
>
> > > > thanks in advance!
>
> > > > On Aug 9, 2:07 pm, MC Get Vizzy <[email protected]> wrote:
> > > > > regarding the refresh interval, is it possible that the underlying
> > data
> > > > has
> > > > > not changed? if the data has not changed, your callback will not be
> > > > called.
> > > > > regarding the redraw, what you have should work -- let me know if you
> > > > have
> > > > > further questions.
>
> > > > > On Tue, Aug 4, 2009 at 10:56 AM, Hazer <[email protected]> wrote:
>
> > > > > > Hi,
>
> > > > > > I have successfully created a PieChart which receives its DataTable
> > > > > > via the Query.send method. However, it does not fire this method
> > after
> > > > > > the first time.
>
> > > > > > Query query = Query.create("http://localhost:8084/
> > > > > > FetchDataTable");
> > > > > > query.setRefreshInterval(5);
> > > > > > query.send(new Callback(){
> > > > > > public void onResponse(QueryResponse response) {
> > > > > > if (response.isError())
> > > > > > SC.say("An error occured: " +
> > > > > > response.getDetailedMessage());
> > > > > > else
> > > > > > {
> > > > > > dataTable = response.getDataTable();
> > > > > > pie = new PieChart(dataTable,
> > > > > > createPieChartOptions(300, 180, "My auto refresh pie chart"));
> > > > > > pie.addSelectHandler
> > > > > > (createPieChartSelectHandler(pie));
> > > > > > hLayout.addMember(pie);
> > > > > > }
> > > > > > }
> > > > > > });
>
> > > > > > I've got 2 questions really:
> > > > > > 1) What is causing the above code to not fire the query.send every
> > 5
> > > > > > secs?
> > > > > > 2) This onResponse creates a new pie chart and adds it to hLayout
> > upon
> > > > > > every successful response. I'm assuming the correct thing would be
> > to
> > > > > > call pie.draw(dataTable, createPieChartOptions(300, 180, "My auto
> > > > > > refresh pie chart"))
> > > > > > I also assume I shouldn't be creating a new PieChart in the
> > > > > > onResponse, so it must already have been created, but how can I
> > create
> > > > > > it AND add it to my DOM before I have my first dataTable?
>
> > > > > > Here's an attempt to create the "empty" pie chart beforehand:
>
> > > > > > pie = new PieChart();
> > > > > > pie.addSelectHandler(createPieChartSelectHandler
> > > > > > (pie));
> > > > > > hLayout.addMember(pie);
>
> > > > > > Query query = Query.create("
> > > > > >http://localhost:8084/FetchDataTable";);
> > > > > > query.setRefreshInterval(5);
> > > > > > query.send(new Callback(){
> > > > > > public void onResponse(QueryResponse response) {
> > > > > > if (response.isError())
> > > > > > SC.say("An error occured: " +
> > > > > > response.getDetailedMessage());
> > > > > > else
> > > > > > {
> > > > > > dataTable = response.getDataTable();
> > > > > > pie.draw(dataTable,
> > createPieChartOptions
> > > > > > (300, 180, "My auto refresh pie chart"));
> > > > > > }
> > > > > > }
> > > > > > });
>
> > > > > > ...but again, the query.send doesn't get called more than once. :(
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Google Visualization API" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/google-visualization-api?hl=en
-~----------~----~----~----~------~----~------~--~---
