bulk_update_or_create

gistfile1.txt

def bulk_update_or_create(model_class, model_data):
    """
    Performs update_or_create in bulk (w/ only 3 db hits)

    Parameters
    ----------
    model_class : django.db.models.Model
        model to update_or_create
    model_data : list
        data to update/create.  Example: [{'field1': 'value', 'field2': 'value'}, ...]

    Returns
    -------
    tuple
        the number of objects created & updated
    """

    # get all instances of the model...
    existing_objects = list(model_class.objects.all())

    # get all the fields that uniquely identify a model object...
    # TODO: deal w/ unique_together fields
    unique_field_names = [
        field.name for field in model_class._meta.get_fields()
        if field.unique and not field.primary_key
    ]
    all_data_record_field_names = set()

    objects_to_create = []
    objects_to_update = []

    for data_record in model_data:

        # for every dictionary in model_data,
        # extract the fields that can uniquely identify an object,
        # and check if there is an existing object w/ those values,
        # if so update that object w/ the field values and store it to be UPDATED,
        # and remove it from the list of existing objects (so the next time around the check is faster),
        # if not store it to be CREATED

        all_data_record_field_names.update(data_record.keys())
        unique_data_record_fields = {
            # raises a KeyError if data doesn't include unique_fields
            field_name: data_record[field_name]
            for field_name in unique_field_names
        }

        matching_object = next(
            (obj for obj in existing_objects if all([getattr(obj, k) == v for k, v in unique_data_record_fields.items()])),
            None
        )
        if matching_object:
            for k, v in data_record.items():
                setattr(matching_object, k, v() if callable(v) else v)
            objects_to_update.append(matching_object)
            existing_objects.remove(matching_object)
        else:
            objects_to_create.append(model_class(**data_record))

    model_class.objects.bulk_create(objects_to_create)
    model_class.objects.bulk_update(objects_to_update, all_data_record_field_names)

    return (len(objects_to_create), len(objects_to_update))