Django: Get an object form the DB, or 'None' if nothing matches

Question

Is there any Django function which will let me get an object form the database, or None if nothing matches?

Right now I\'m using something like:

foo          


        

Answer 1

Here's a variation on the helper function that allows you to optionally pass in a QuerySet instance, in case you want to get the unique object (if present) from a queryset other than the model's all objects queryset (e.g. from a subset of child items belonging to a parent instance):

def get_unique_or_none(model, queryset=None, *args, **kwargs):
    """
        Performs the query on the specified `queryset`
        (defaulting to the `all` queryset of the `model`'s default manager)
        and returns the unique object matching the given
        keyword arguments.  Returns `None` if no match is found.
        Throws a `model.MultipleObjectsReturned` exception
        if more than one match is found.
    """
    if queryset is None:
        queryset = model.objects.all()
    try:
        return queryset.get(*args, **kwargs)
    except model.DoesNotExist:
        return None

This can be used in two ways, e.g.:

1. obj = get_unique_or_none(Model, *args, **kwargs) as previosuly discussed
2. obj = get_unique_or_none(Model, parent.children, *args, **kwargs)