Vaadin Form commit() method?

Question

I have some problem with understanding what the commit() method really does in Vaadin. I read the documentation, did some examples but I am misunderstanding what it actually is.

This is snippet of code:

if (source == save) {
     /* If the given input is not valid there is no point in continuing */
    if (!isValid()) {
        return;
    }

    if (newContactMode) {
         /* We need to add the new person to the container */
        Item addedItem = app.getDataSource().addItem(newPerson);
         /*
          * We must update the form to use the Item from our datasource
          * as we are now in edit mode
          */
        setItemDataSource(addedItem);
        //System.out.println(app.getDataSource().getItem(addedItem));
        newContactMode = false;
    }

    commit();
    setReadOnly(true);
}

If I do things this way, then I don't add some of the data added in the Form of the DataSource (in the Container). Those entries aren't showing in the table.

Another snippet of code:

if (source == save) {
     /* If the given input is not valid there is no point in continuing */
    if (!isValid()) {
        return;
    }
    commit();//changing place of this method
    if (newContactMode) {
         /* We need to add the new person to the container */
        Item addedItem = app.getDataSource().addItem(newPerson);
         /*
          * We must update the form to use the Item from our datasource
          * as we are now in edit mode
          */
        setItemDataSource(addedItem);
        //System.out.println(app.getDataSource().getItem(addedItem));
        newContactMode = false;
    }
    setReadOnly(true);
}

This version works correctly. I can conclude that this method in the form do block for all interactions with "DataSource" (with items in DataSource) for this Form. But I need to do it directly, through invocation another class and Container's addItem(). I haven't found any good explanation about commit() method.

I have been using this tutorial, maybe someone will recognize this GUI from the tutorial.

Answer 1

I understood what is wrong. In the second snippet i filled out my newPerson instance with data from form by invocation of commit(). In the first snippet i have written null data because i didn't invoke method commit() before and binding object is null(not written yet).