C validating data types
Data Elements represent the data containers at the leafs.
You can explicitly create tree Elements with the factory.
To make the doctests in this document look a little nicer, we also use this: In addition to the normal Element Tree API for appending elements to trees, subtrees can also be added by assigning them to object attributes.
Then we select the “Validate” tab to see the validation options: The default is that the field will not get validated.In lxml.objectify, this directly translates to enforcing a specific object tree, i.e.expected object attributes are ensured to be there and to have the expected type.In the latter case, we set rc to false, and also display an error message.
When you play around with the function, you’ll notice that the validation function is only called when the focus leaves the field, so you have to click outside of the field to actually make that error message pop up.The algorithm is as follows: Care must be taken if different namespace prefixes have been used for the same namespace.