How to calculate column footer total in filtered grid

Vaadin 6 / 7 / 8
1

I understand that I have to use grid.getDataProvider() to get the ListDataProvider (assuming I sent a List to grid.setItems()). In other to calculate the footer total I do:

Collection myItems = ((ListDataProvider)grid.getDataProvider()).getItems();
for(MyItem myItem : myItems)
   total += myItem.getValue();
footer.getCell(footerCell).setText(format(total));

But what happens if I did:

((ListDataProvider)grid.getDataProvider()).addFilter(myFilter);

If I do the initial loop way above it includes even the filtered items. In other words how can I get a total for only those items that are visible in the grid, the filtered items?

2

Instead of getItems() you should use fetch(…) method of the data provider. With fetch you can apply same filters with a Query or sorting than in Grid, and get stream of items, that matches what you want.

3

I looked at that but fetch() requires a query which I don’t understand. Also how does it link to the filters. Would you be so kind as to provide a code example because I have no idea how the query parameter of fetch() works. Also if you have any links to documentation that would be appreciated. All I could find was the API and it had no details or examples other than saying it was a query…

Thank you.

4

See discussion here:

https://github.com/vaadin/framework/issues/10115

​Actually this approach could suite you as well.

grid.getDataCommunicator().fetchItemsWithRange(…)

5

fetchItemsWithRange() is a protected method. Also how do you know what the range is because the items are filtered? The link is just to get an item at a specific index, I don’t understand how it would work. I don’t know which items are present because the data is filtered…

6

Does anyone have any further ideas on this?

7

fetchItemsWithRange() will be available in Vaadin 8.2.0

With Vaadin 8.x version below 8.2.0 you need to use the longer version as described in #10115

8

Thank you, I both completely forgot it from before and missed it this time.

9

Can you please expand on how to use fetchItemsWithRange() I see that it’s available in 8.2.0 but how exactly do you call it? Say I’ve got:

List<Pojo> myList = getListOfPojos();
grid.setItems(myList);
grid.getDataCommunicator().fetchItemsWithRange();

What would be the parameter of fetchItemsWithRange? Would it be 0, myList.size() ? I ask because tried that and the result was nothing was filtered.

Or maybe as you said use the fetch() method, but the problem is that I don’t understand how to use it. What do I use for the Query parameter?

Just to re-iterate what I’m trying to do is reload the grid after an action has taken place. Not necessarily a delete but some other action which can affect multiple rows, etc. And when I reload the filters need to be re-applied.

10

I have the same question. What should be the parameter for fetchItemsWithRange() ?
I have a TreeGrid with sum being displayed in the footer. When there is a filter applied to the grid, I want the sum to update.
Can’t seem to understand the syntax.
FYI i also tried using fetch() → it says non hierarchical queries are not allowed for heirarchical, so i tried using fetchChildren - that requires HierarchicalQuery instead of Query which again, i dont understand what should be the parameter for that…

11

@Stephan
I found the solution for your answer here: https://stackoverflow.com/questions/46722217/how-to-calculate-the-total-in-a-vaadin-8-grid-footer-with-filtering

But I cannot use that solution since I am using a TreeGrid.

@Tatu
Is there any example of updating the footer after items have been filtered when a TreeGrid is being used?