Snippets show all languages in original version

[zemogle]

I'm sure I must be doing something wrong here. When editing the original language of a page, all the snippets show values for every language.

This is how the model and snippet is constructed.

@register_snippet
class Level(TranslatableMixin):
    name = models.CharField(max_length=255)
    def __str__(self):
        return self.name

    class Meta:
        verbose_name = "Educational Level"
        unique_together = ('translation_key', 'locale')

class Activity(Page):
       ...
       level = ParentalManyToManyField(Level, verbose_name='Education level', blank=True)

        MultiFieldPanel([
           ....
            FieldPanel('level', widget=forms.CheckboxSelectMultiple),
        ])

We're just about to expand to more than 2 languages and this will get crazy.

[zerolab]

This is a duplicate of #534

tl;dr there is nothing that would instruct the field panel as to what the current locale is and what to filter things on.

You probably want to define your own FieldPanel that does the filtering on being bound to the form. e.g. in https://github.com/wagtail/wagtail/blob/3b77e23cfe71bdd1c482c7be9721ceeb687db6b9/wagtail/admin/panels.py#L669

[zemogle]

Thanks. I used #534 in the end because I couldn't wrap my head around filtering the snippet queryset. Its not an ideal solution and I'll keep looking into creating a custom FieldPanel. Any pointers would be really helpful.

[enzedonline]

Turns out the locale is lurking in the BoundPanel.instance

Here's a select panel that will filter according to locale. It'll match the default panel type for the field, or you can override with an appropriate form widget (one of CheckboxSelectMultiple, RadioSelect, Select or SelectMultiple). Set typed_choice_field=True to force Select into a dropdown widget (default is a list).

from django.core.exceptions import ImproperlyConfigured
from django.forms.models import ModelChoiceIterator
from django.forms.widgets import (CheckboxSelectMultiple, RadioSelect, Select,
                                  SelectMultiple)
from django.utils.translation import gettext_lazy as _
from wagtail.admin.panels import FieldPanel


class LocalizedSelectPanel(FieldPanel):
    """
    Customised FieldPanel to filter choices based on locale of page/model being created/edited
    Usage: 
    widget_class - optional, override field widget type
                 - should be CheckboxSelectMultiple, RadioSelect, Select or SelectMultiple
    typed_choice_field - set to True with Select widget forces drop down list 
    """

    def __init__(self, field_name, widget_class=None, typed_choice_field=False, *args, **kwargs):
        if not widget_class in [None, CheckboxSelectMultiple, RadioSelect, Select, SelectMultiple]:
            raise ImproperlyConfigured(_(
                "widget_class should be a Django form widget class of type "
                "CheckboxSelectMultiple, RadioSelect, Select or SelectMultiple"
            ))
        self.widget_class = widget_class
        self.typed_choice_field = typed_choice_field
        super().__init__(field_name, *args, **kwargs)

    def clone_kwargs(self):
        return {
            'heading': self.heading,
            'classname': self.classname,
            'help_text': self.help_text,
            'widget_class': self.widget_class,
            'typed_choice_field': self.typed_choice_field,
            'field_name': self.field_name,
        }

    class BoundPanel(FieldPanel.BoundPanel):
        def __init__(self, **kwargs):
            super().__init__(**kwargs)           
            if not self.panel.widget_class:
                self.form.fields[self.field_name].widget.choices=self.choice_list
            else:
                self.form.fields[self.field_name].widget = self.panel.widget_class(choices=self.choice_list)
            if self.panel.typed_choice_field:
                self.form.fields[self.field_name].__class__.__name__ = 'typed_choice_field'
            pass

        @property
        def choice_list(self):
            self.form.fields[self.field_name].queryset = self.form.fields[self.field_name].queryset.filter(locale_id=self.instance.locale_id)
            choices = ModelChoiceIterator(self.form.fields[self.field_name])
            return choices

So in your Activity class, you'd call this with

LocalizedSelectPanel(
    'level', 
    widget_class=CheckboxSelectMultiple, 
    ),