What does webform prefilling exactly do?
Your forms will remember your details, if you already provided them once. They get saved in the session storage of your browser (that's not the same as a cookie) but some really old browsers might not support it.
> What funny things can you do with it?
Beside the obvious advantage that your supporters, that take part in more than one action, don't need to re-type their details, you can do fancy little things like this:
You could ask supporters on the thank-you-page to subscribe to your newsletter just with a checkbox and a submit button. Do this, by creating a flexible form and add its block to your thank you page. For the flexible form hide the name and email fields and just set the newsletter checkbox to visible. Name and email fields will get prefilled with the supporters details.
> Prefill vs. Default Values
What are default values and how are they used?
You can give a field in your form a default value (for instance your preferred donation amount). But you can also give out different default values if you use GET parameter. And here it's use is similar to webform prefill, but with different purposes.
- default values with GET parameters
You can hand out different URLs depending on your channels, that set different default values for your form. For instance:
If you set %get[p12] as your default value in your form, an URL like this: https://your-site/yourform?p12=200 will set the value of this field to 200 (the value of the GET parameter).
- default values will be overridden by prefill values
If prefill is enabled and data is available for the field, the default value will be overridden.
How do I get webform prefilling?
webform_prefill is an open source Drupal modul more onion developed. You can get it here: Github - webform_prefill
Or if you are hosting with more onion, just ask us :-)
Can I exclude certain form fields from getting prefilled?
If you want certain fields to not be prefilled, there is a CSS class that you can add to the form field via the "Display" tab, on the form step when editing the action: webform-prefill-exclude
There is also it's counterpart: webform-prefill-include
On the more onion blog