pentaho first steps: link combobox to chart - charts

Question

I'm completely new to SO, Pentaho, and have a (very) limited knowledge on js and jquery.
I need a simple requirement: whenever my combobox changes (2 values: budget or estimate), I need to reload my chart.
What I've tried so far:
In Components panel, I've added a
-Simple Parameter
--Name: param_budget_or_estimate
--Property value: budget
-Select component
--Name: BudgetEstimate_Select
--Parameter: budget_or_estimate
--Datasource: budgetestimate_query
-CCC Pie Chart
--Name: piechart_linecosts
--Listeners: added param_budget_or_estimate
--Parameters: arg param_budget_or_estimate, value param_budget_or_estimate
--Datasource: budgestimate_piechart
In Datasrouces panel, I've added a
-sql over sqlJndi query budgetestimate_query, named budgetestimate_query, that returns a
select distinct budget_or_estimate from budget_or_estimate;
-sql over sqlJndi query named budgetestimate_piechart, that returns a
SELECT COST_LINE_NAME
,amount
FROM VI_LINE_COSTS_PIE_CHART
WHERE budget_or_estimate=${param_budget_or_estimate}
;
Yet, I fire up my dashboard and changing the combobox changes nothing.
What am I doing wrong?
Thanks in advance!

Answer 1

First, you need to create a parameter. Let it be named parameter_one.
Then, you set your select component to have parameter_one as Parameter property (so it propagates the onchange event's value to the parameter).
Now, the piechart must have parameter_one as listeners, and parameter_one as parameters (arg=parameter_one, value=parameter_one). So, you declare that whenever parameter_one changes, the piechart should be reoloaded (listener) and that parameter_one's value is relevant to the calculation (parameter).
Finally, the piechart DataSource should look like:
select A.id,A.value
FROM
(
select '1' as id, 10 as value
union all
select '2' as id, 20 as value
) A
WHERE A.id=${parameter_one}
;