Edit branch details form need input validation for non-existent product

The validate() function for that form should be using data.get('product') rather than data['product'].

Since the data from the request didn't result in a valid product name, the product object doesn't get added to the data dictionary. The validate() method needs to cope with this.

Duh? I assumed that if the interface/vocabulary validation failed the view's validate() method would not be called.

Seems like a bad thing to require the validate method to cope with the absence of attributes. In addition it should not use data.get('product') because the None value (no product, junk branch) is perfectly valid here.

There is a good reason to call the validate() method on field errors: we want to present all the validation errors to the user upfront, rather than have them fix the returned errors only to have new ones given on the next submission.

Using the branch edit form as an example, imagine that the user entered a value into the title field that caused a field validation error (e.g. they snuck in a new line character), and chose a branch name that was already in use. We'd want to display both errors to the user, which means invoking validate() even though we got a field validation error.

Fix committed to rocketfuel as r4034

This change was included in today's rollout.