tests/form_pages/test_prefill.py

@@ -479,6 +479,89 @@ def test_form_page_profile_prefill_list(pub):
     assert resp.forms[0]['f0'].value == ''
 
 
+def test_form_page_item_with_variable_data_source_prefill(pub):
+    create_user(pub)
+    formdef = create_formdef()
+    formdef.data_class().wipe()
+    formdef.fields = [
+        fields.StringField(
+            id='1', label='string', varname='string', prefill={'type': 'string', 'value': 'foobar'}
+        ),
+        fields.ItemField(
+            id='2',
+            label='item',
+            varname='item',
+            required=False,
+            data_source={'type': 'foobar'},
+            prefill={'type': 'string', 'value': '4'},
+        ),
+    ]
+    formdef.store()
+
+    NamedDataSource.wipe()
+    data_source = NamedDataSource(name='foobar')
+    data_source.data_source = {
+        'type': 'json',
+        'value': 'http://example.net/{{form_var_string}}',
+    }
+    data_source.store()
+
+    with responses.RequestsMock() as rsps:
+        rsps.get('http://example.net/None', json={'data': [{'id': '1', 'text': 'hello'}]})
+        rsps.get(
+            'http://example.net/foobar',
+            json={'data': [{'id': '1', 'text': 'hello'}, {'id': '4', 'text': 'world'}]},
+        )
+        resp = get_app(pub).get('/test/')
+        assert len(rsps.calls) == 2
+        assert rsps.calls[0].request.url == 'http://example.net/None'
+        assert rsps.calls[1].request.url == 'http://example.net/foobar'
+        assert [x.attrib['value'] for x in resp.pyquery('#form_f2 option')] == ['1', '4']
+        assert resp.form['f2'].value == '4'
+        assert not resp.pyquery('#form_error_f2').text()
+
+
+def test_form_page_item_with_computed_field_variable_data_source_prefill(pub):
+    create_user(pub)
+    formdef = create_formdef()
+    formdef.data_class().wipe()
+    formdef.fields = [
+        fields.ComputedField(
+            id='1',
+            label='string',
+            varname='string',
+            value_template='foobar',
+        ),
+        fields.ItemField(
+            id='2',
+            label='item',
+            varname='item',
+            required=False,
+            data_source={'type': 'foobar'},
+            prefill={'type': 'string', 'value': '4'},
+        ),
+    ]
+    formdef.store()
+
+    NamedDataSource.wipe()
+    data_source = NamedDataSource(name='foobar')
+    data_source.data_source = {
+        'type': 'json',
+        'value': 'http://example.net/{{form_var_string}}',
+    }
+    data_source.store()
+
+    with responses.RequestsMock() as rsps:
+        rsps.get(
+            'http://example.net/foobar',
+            json={'data': [{'id': '1', 'text': 'hello'}, {'id': '4', 'text': 'world'}]},
+        )
+        resp = get_app(pub).get('/test/')
+        assert [x.attrib['value'] for x in resp.pyquery('#form_f2 option')] == ['1', '4']
+        assert resp.form['f2'].value == '4'
+        assert not resp.pyquery('#form_error_f2').text()
+
+
 def test_form_page_formula_prefill_items_field(pub):
     create_user(pub)
     formdef = create_formdef()

wcs/formdef.py

@@ -964,6 +964,9 @@ class FormDef(StorableObject):
                 if widget:
                     widget.live_condition_source = True
                     widget.live_condition_fields = live_condition_fields[field.varname]
+                elif field.key == 'computed':
+                    field.live_condition_source = True
+                    field.live_condition_fields = live_condition_fields[field.varname]
 
     @classmethod
     def get_field_data(cls, field, widget, raise_on_error=False):

wcs/forms/root.py

@@ -522,13 +522,6 @@ class FormPage(Directory, TempfileDirectoryMixin, FormTemplateMixin):
                     form.get_widget('f%s' % block.id).unparse()
                     form.get_widget('f%s' % block.id).clear_error()
 
-                if field.key == 'item' and v:
-                    # mark field as invalid if the value is not allowed
-                    # (this is required by quixote>=3 as the value would
-                    # not be evaluated in the initial GET request of the
-                    # page).
-                    widget._parse(req)
-
                 had_prefill = True
         return had_prefill
 
@@ -577,9 +570,8 @@ class FormPage(Directory, TempfileDirectoryMixin, FormTemplateMixin):
             magictoken = randbytes(8)
             has_new_magictoken = True
 
-        computed_data = self.handle_computed_fields(
-            magictoken, self.formdef.get_computed_fields_from_page(page)
-        )
+        computed_fields_on_page = list(self.formdef.get_computed_fields_from_page(page))
+        computed_data = self.handle_computed_fields(magictoken, computed_fields_on_page)
         if computed_data:
             form_data.update(computed_data)
             self.feed_current_data(magictoken)
@@ -687,18 +679,24 @@ class FormPage(Directory, TempfileDirectoryMixin, FormTemplateMixin):
 
         if had_prefill:
             # pass over prefilled fields that are used as live source of item
-            # fields
+            # fields, update matching list of options of matching fields,
+            # and mark fields as invalid if the selected value is not available.
             fields_to_update = set()
+            for field in computed_fields_on_page:
+                if getattr(field, 'live_condition_source', False):
+                    fields_to_update.update(field.live_condition_fields)
             for field, field_key, widget, dummy, dummy in self.iter_with_block_fields(form, displayed_fields):
                 if getattr(widget, 'prefilled', False) and getattr(widget, 'live_condition_source', False):
                     fields_to_update.update(widget.live_condition_fields)
-                elif field in fields_to_update and field.key == 'item':
+                elif field.key == 'item':
                     kwargs = {}
                     with get_publisher().substitutions.temporary_feed(transient_formdata, force_mode='lazy'):
-                        field.perform_more_widget_changes(form, kwargs)
-                        if 'options' in kwargs and 'options_with_attributes' in kwargs:
-                            widget.options = kwargs['options']
-                            widget.options_with_attributes = kwargs['options_with_attributes']
+                        if field in fields_to_update:
+                            field.perform_more_widget_changes(form, kwargs)
+                            if 'options' in kwargs:
+                                widget.options = kwargs['options']
+                                widget.options_with_attributes = kwargs.get('options_with_attributes')
+                        widget._parse(req)
 
         self.set_page_title()