def validate_alias(self, value):
    subproject = self.parent_project.subprojects.filter(alias=value)
    if subproject.exists():
        raise serializers.ValidationError(_('A subproject with this alias already exists'))
    return value
def validate_alias(self, value):
    subproject = self.parent_project.subprojects.filter(alias=value)
    if subproject.exists():
        raise serializers.ValidationError(_('A subproject with this alias already exists'))
    return value