[Django]-Render only one part of a MultiWidget in Django

by

5👍

✅

I found a solution to this problem that needs two pieces of code.

First

The render method that turns the MultiWidget into a string is relatively long. We need to copy&paste it with a tiny modification in the last line to make it returing an array instead.

class OurMultiWidget(forms.MultiWidget):
    ...

    def render(self, name, value, attrs=None):
        """Copy and past from original render method"""
        if self.is_localized:
            for widget in self.widgets:
                widget.is_localized = self.is_localized
        # value is a list of values, each corresponding to a widget
        # in self.widgets.
        if not isinstance(value, list):
            value = self.decompress(value)
        output = []
        final_attrs = self.build_attrs(attrs)
        id_ = final_attrs.get('id', None)
        for i, widget in enumerate(self.widgets):
            try:
                widget_value = value[i]
            except IndexError:
                widget_value = None
            if id_:
                final_attrs = dict(final_attrs, id='%s_%s' % (id_, i))
            output.append(widget.render(name + '_%s' % i, widget_value, final_attrs))
        # Original:
        # return mark_safe(self.format_output(output))
        # Only this line was written by myself:
        return [mark_safe(self.format_output(x)) for x in output]

Second

Writing {{ formname.fieldname }} in the template will automatically call the field’s unicode method and treat the result as a string. As we want an array instead, we need to circumvent the unicode method and access directly what it will return. And this is the method as_widget. Thus, to call the first part of OurMultiWidget, we will need this code in the template:

{{ formname.fieldname.as_widget.0 }}
👤Philipp Zedler

2👍

Philipp Zedler’s answer is amazing, but doesn’t work on Django 3.1 because the way rendering works has changed. Unfortunately Django 3.1’s MultiWidget seems a little broken so iterating through subwidgets still doesn’t Just Work, but luckily the fix is much simpler.

MultiWidget seems to be missing the following method override:

    def subwidgets(self, name, value, attrs=None):
        context = self.get_context(name, value, attrs)
        return context['widget']['subwidgets']

If you add this method to your own subclass of MultiWidget, you will be able to iterate through the subwidgets as follows:

<h2>{{ form.myfield.label }}</h2>
<ul>
  {% for w in form.myfield.subwidgets %}
  <li>{{ w }}</li>
  {% endfor %}
</ul>
👤Tim Band

Leave a comment