Error in forms listing in admin

Issue Summary

I have a site which i was working well with wagtail -2.16.x, i’m making a renewal and migration of the whole site, i have a few forms, but when i did try to test it, seems to work twice, but when i look in admin section ‘Forms’ an error appears about ‘str’ object is not a mapping

Steps to Reproduce

1. Start a new project with wagtail start myproject
2. Edit models.py to add a AbstractFormField model, and a AbstractEmailForm model:

class FormularioFormField(AbstractFormField): pagina = ParentalKey(“Formulario”, on_delete=models.CASCADE, related_name=“campos_formulario”) …

class Formulario(PaginaBaseAbstract, AbstractEmailForm): …

1. Create a few pages in admin of type ‘Formulario’
2. Go to public view fo that form and fill a few forms.
3. return to wagtail admin, and go to forms
4. open your forms with data filled
5. see that error jumps…

• I have confirmed that this issue can be reproduced as described on a fresh Wagtail project: YES

Technical details

• Python version: 3.10
• Django version: 4.0.1
• Wagtail version: 3.0
• Browser version: Firefox 99

btw, i found the solution, in the file wagtail/contrib/forms/models.py

line 57 (into get_data func):

**self.form_data,

def get_data(self):
     """
     Returns dict with form data.
     You can override this method to add additional data.
     """
     return {
         **self.form_data,
         "submit_time": self.submit_time,
     }

checking the same file in 2.16 y change a bit to make it similar, so i change it to:

def get_data(self):
     form_data = json.loads(self.form_data)
     form_data.update({'submit_time': self.submit_time})
     return form_data

obviously must import json first

[gasman]

For reference, the same thing has been reported on the Wagtail Slack support channel but is unresolved there - if this does turn out to be a missed step in the upgrade process then we should highlight this in the release notes.

[tbrlpld]

I just ran into this issue too. It looks like I had a bad record in the database. I guess that record was created after the migration ran to convert the table to JSON but before I had updated the process_form_submission to not use json.dumps anymore.

Here you can see the bad record in the database with id 4.

picnic=# select * from myforms_myformsubmission;
 id |              form_data               |          submit_time          | page_id | user_id 
----+--------------------------------------+-------------------------------+---------+---------
  1 | {"what_is_your_name": "Alice"}       | 2022-10-11 14:11:16.587711+00 |       5 |       1
  2 | {"what_is_your_name": "Bob"}         | 2022-10-11 14:11:23.633996+00 |       5 |       1
  3 | {"what_is_your_name": "Alice again"} | 2022-10-17 15:30:33.813545+00 |       5 |        
  4 | "{\"what_is_your_name\": \"Test\"}"  | 2022-10-19 13:47:23.80316+00  |       5 |        
  5 | {"what_is_your_name": "Test"}        | 2022-10-19 13:48:12.425547+00 |       5 |        
(5 rows)

picnic=# delete from myforms_myformsubmission where id=4;
DELETE 1
picnic=# select * from myforms_myformsubmission;
 id |              form_data               |          submit_time          | page_id | user_id 
----+--------------------------------------+-------------------------------+---------+---------
  1 | {"what_is_your_name": "Alice"}       | 2022-10-11 14:11:16.587711+00 |       5 |       1
  2 | {"what_is_your_name": "Bob"}         | 2022-10-11 14:11:23.633996+00 |       5 |       1
  3 | {"what_is_your_name": "Alice again"} | 2022-10-17 15:30:33.813545+00 |       5 |        
  5 | {"what_is_your_name": "Test"}        | 2022-10-19 13:48:12.425547+00 |       5 |