Django snippets

Comments

akaihola (on September 16, 2007):

Ticket #5126 has a patch for including this functionality in Django.

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akaihola (on September 25, 2007):

The function didn't handle dates correctly, at least when feeding instance data to a form with a SelectDateWidget.

I also wanted to use it for unsaved objects, but they failed on many-to-many fields.

Here's a version which fixes both these problems:

def instance_dict(instance, key_format=None):
    """
    Returns a dictionary containing field names and values for the given
    instance
    """
    from django.db.models.fields import DateField
    from django.db.models.fields.related import ForeignKey
    if key_format:
        assert '%s' in key_format, 'key_format must contain a %s'
    key = lambda key: key_format and key_format % key or key

    pk = instance._get_pk_val()
    d = {}
    for field in instance._meta.fields:
        attr = field.name
        value = getattr(instance, attr)
        if value is not None:
            if isinstance(field, ForeignKey):
                value = value._get_pk_val()
            elif isinstance(field, DateField):
                value = value.strftime('%Y-%m-%d')
        d[key(attr)] = value
    for field in instance._meta.many_to_many:
        if pk:
            d[key(field.name)] = [
                obj._get_pk_val()
                for obj in getattr(instance, field.attname).all()]
        else:
            d[key(field.name)] = []
    return d

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