NoneRelationship and NonePageItem

A NoneRelationship is a subclass of Relationship that represents a non-existent relationship. Think of it as a None that is also a Relationship.

A NoneRelationship is returned by _parse_relationship() in Node, when there is an expected relationship but it isn’t in the returned data.

For example:

members = organization.team_members  # the data we got from CrunchBase was missing the team_members realtionship
assert instanceof(members[0], NoneRelationship) == True

The benefit of this is that calling the conventional relationship methods, such as get(), will return an object, rather than throwing an AttributeError:

members = organization.team_members
first_member = members.get(0)  # will not explode
assert bool(first_member) == False

Because Relationship are made up of PageItem, we have a similar None for it as well, called NonePageItem. The idea behind it is similar to what was discussed above as well:

# continuing the example from above, we have member
first_member = members.get(0)  # will not explode
assert first_member.name == None
assert first_member.whatever == None