JDev 11.1.1.3: Column Sum needs to work like getEstimatedRowCount

Question

Hi there,
I am working with the table component and a large dataset (thousands of rows).
I need to see a column total (sum) in the column footer. Since we're dealing with a large dataset, I thought the appropriate way to do this is to select sum(columnName) which works just fine.
What I want my total to do though is to also act dynamically to changes in data within the table so that if I insert a new row or update a row, the total will change.
I thought of the getEstimatedRowCount method and how it selects count(*) and also merges local information such as row inserts and deletes to give you the proper row count.
I want a way that I can get my sum in the same manner. So that I can select sum(columnName) and also keep track of the local changes.
Any thoughts of how to do this ?
Thanks,
Mark

Answer 1

Hi,
what about
- Managed Bean in ViewScope to hold the SUM value.
- Summary field that references SUM value from its value property
- When managed bean instantiates, access ViewObject and issue query select sum(...) from ...
- Define a value change listener on column cell field and have it referencing the same managed bean
- Set the column cell have its autosubmit property set to true so the value change is called whenever the user leaves the field
- In the value change listener, compare valueChangeEvent.getOldValue with valueChangeEvent.getNewValue and build the Diff
- Update the SUM value in the managed bean
- Access the SUM field (the UI component to show the SUM from the managed bean) and PPR it
This should work best and performant
Frank