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Vaadin Forum3. Vaadin 6, 7, 8Framework Data Binding

SQLContainer iteration

Hugo Hanisch
1 decade ago Mar 20, 2012 4:00pm

Hi:

How do I iterate over a SQLContainer, for example, to add all the data in one column to a string....

regards,

Hugo

+1
Jonatan Kronqvist
1 decade ago Mar 21, 2012 8:01am

Hi,

SQLContainer implements the IndexedContainer interface, so you can do something like this:

for (int i = 0; i < container.size(); i++) {
    Object id = container.getIdByIndex(i);
    Item item = container.getItem(id);
    // do stuff with item
}

The only thing to remember is to avoid the getItemIds() method if at all possible, since this method will load all rows from the database, which can be very slow if you have a huge dataset.

Or if you mean to display additional computed cells in a table, you should check out Table.addGeneratedColumn().

HTH,
/Jonatan

+1
Hugo Hanisch
1 decade ago Mar 22, 2012 1:03am

Jonatan Kronqvist: Hi,

SQLContainer implements the IndexedContainer interface, so you can do something like this:

for (int i = 0; i < container.size(); i++) {
    Object id = container.getIdByIndex(i);
    Item item = container.getItem(id);
    // do stuff with item
}

The only thing to remember is to avoid the getItemIds() method if at all possible, since this method will load all rows from the database, which can be very slow if you have a huge dataset.

Or if you mean to display additional computed cells in a table, you should check out Table.addGeneratedColumn().

HTH,
/Jonatan

Thank you very much Jonatan, I was actually using getItemIds(), so you help a lot with your answer, which worked perfect...

regards,

Hugo

+1
Hugo Hanisch
1 decade ago Apr 05, 2012 2:46pm

Jonatan Kronqvist: Hi,

SQLContainer implements the IndexedContainer interface, so you can do something like this:

for (int i = 0; i < container.size(); i++) {
    Object id = container.getIdByIndex(i);
    Item item = container.getItem(id);
    // do stuff with item
}

The only thing to remember is to avoid the getItemIds() method if at all possible, since this method will load all rows from the database, which can be very slow if you have a huge dataset.

Or if you mean to display additional computed cells in a table, you should check out Table.addGeneratedColumn().

HTH,
/Jonatan

Jonatan:

I have a different problem now, and I'm not sure if I this is the right thread, but is that the getIdByIndex(i) method doesn't work for hierarchical containers...

I'm try this now with a treetable (tree):

for (int i = 0; i < tree.getContainerDataSource().size(); i++) {

				Item item = tree.getContainerDataSource().getItem(tree.getContainerDataSource().getItemIds());
	            Object value =item.getItemProperty(PROPERTY).getValue();

			}

...but it gives me a null pointer exception error....I'm not sure how to fix this...any idea??

regards and ,as always, thank you very much....

Hugo

Jonatan Kronqvist
1 decade ago May 25, 2012 9:59am

Sorry for the late reply, but I don't really understand the code you posted. You talk about getIdByIndex(), but don't call it anywhere. Instead you have a call to getItem(getItemIds()), which I'm sure will return NULL, since getItemIds() will return a collection and not an ID for any item.

Anyway, I guess you already solved the problem :)

/Jonatan