misc: do not crash on invalid file value in workflow variables (#57720)

tests/admin_pages/test_form.py

@@ -870,6 +870,45 @@ def test_form_workflow_table_variables(pub):
     assert resp.form['f2'].value == 'foobar'
 
 
+def test_form_workflow_invalid_file_variable(pub):
+    create_superuser(pub)
+    create_role(pub)
+
+    FormDef.wipe()
+    Workflow.wipe()
+
+    workflow = Workflow(name='Workflow One')
+    from wcs.workflows import WorkflowVariablesFieldsFormDef
+
+    workflow.variables_formdef = WorkflowVariablesFieldsFormDef(workflow=workflow)
+    workflow.variables_formdef.fields = [
+        fields.StringField(id='1', varname='test', label='Test', type='string')
+    ]
+    workflow.store()
+
+    formdef = FormDef()
+    formdef.name = 'form title'
+    formdef.fields = []
+    formdef.store()
+    formdef.workflow_id = workflow.id
+    formdef.store()
+
+    app = login(get_app(pub))
+    resp = app.get('/backoffice/forms/1/workflow-variables')
+    resp.forms[0]['f1'] = 'foobar'
+    resp = resp.forms[0].submit()
+
+    # check the value has been correctly saved
+    assert FormDef.get(formdef.id).workflow_options == {'test': 'foobar'}
+
+    # modify option type
+    workflow.variables_formdef.fields = [fields.FileField(id='1', varname='test', label='Test', type='file')]
+    workflow.store()
+
+    # do not crash when getting back
+    resp = app.get('/backoffice/forms/1/workflow-variables')
+
+
 def test_form_roles(pub):
     create_superuser(pub)
     role = create_role(pub)

wcs/qommon/form.py

@@ -771,11 +771,12 @@ class FileWithPreviewWidget(CompositeWidget):
                     )
                 self.get_widget('token').set_value(self.value.token)
         except Exception as e:
-            get_publisher().record_error(
-                _('Failed to set value on field "%s"') % self.field.label,
-                formdef=getattr(self, 'formdef', None),
-                exception=e,
-            )
+            if getattr(self, 'field', None):
+                get_publisher().record_error(
+                    _('Failed to set value on field "%s"') % self.field.label,
+                    formdef=getattr(self, 'formdef', None),
+                    exception=e,
+                )
             self.value = None
 
     def add_media(self):