Support deleting keys in json_form_fields

If the attribute delete_on_empty is set to True on the Field, and the
value submitted from the user is empty, delete the key from the json
object instead of setting it to the empty string. The default behaviour
remains the previous one, which is set the key explicitly to the empty
string.

1 files changed, 7 insertions, 1 deletions

diff --git a/postgresqleu/util/backendviews.py b/postgresqleu/util/backendviews.py
index e1eb614b..685320d9 100644
--- a/postgresqleu/util/backendviews.py
+++ b/postgresqleu/util/backendviews.py
@@ -181,7 +181,13 @@ def backend_process_form(request, urlname, formclass, id, cancel_url='../', save
                 if form.json_form_fields:
                     for fn, ffields in form.json_form_fields.items():
                         d = getattr(form.instance, fn, {})
-                        d.update({fld: form.cleaned_data[fld] for fld in ffields})
+                        for fld in ffields:
+                            if form.cleaned_data[fld] or not getattr(form.fields[fld], 'delete_on_empty', False):
+                                # If we have a value, or if we're asked to store empty strings,
+                                # then do so.
+                                d[fld] = form.cleaned_data[fld]
+                            elif form.cleaned_data[fld] == '' and getattr(form.fields[fld], 'delete_on_empty', False):
+                                del d[fld]
                         setattr(form.instance, fn, d)
                     form.instance.save(update_fields=form.json_form_fields.keys())