Django concatenate non null fields. #snippet

concat_non_null_fields.py

# Ended up not using this, as there was only one place in the codebase.


def concat_non_null_fields(fields, seperator):
    """
    Build a case statement expression to concatenate the supplied fields where isnull is False.

    :param fields: List of fields to concatenate.
    :param seperator: Seperator to use between fields.
    :return: Case statement expression.

    Loops through each field and adds a case statement that adds the field if present, along
    with a seperator, if not then an empty string is added.
    """
    return Concat(
        *[
            Case(
                When(f"{field}__isnull", Value("")),
                default=Concat(Value(seperator), F(field)),
                output_field=CharField(),
            )
            for field in fields],
        output_field=CharField()
    )