=====================
Subscription services
=====================

The `ISubscriptionService` utility provides higher level convenience methods
useful for searching, retrieving, iterating, adding, and removing
memberships.

    >>> from mailman.interfaces.subscriptions import ISubscriptionService
    >>> from zope.component import getUtility
    >>> service = getUtility(ISubscriptionService)

You can use the service to get all members of all mailing lists, for any
membership role.  At first, there are no memberships.

    >>> service.get_members()
    []
    >>> sum(1 for member in service)
    0
    >>> from uuid import UUID
    >>> print(service.get_member(UUID(int=801)))
    None


Adding new members
==================

The service can be used to subscribe new members, by default with the `member`
role.  At a minimum, a mailing list and an address for the new user is
required.

    >>> mlist = create_list('test@example.com')
    >>> anne = service.join('test.example.com', 'anne@example.com')
    >>> anne
    <Member: anne <anne@example.com> on test@example.com as MemberRole.member>

The real name of the new member can be given.

    >>> bart = service.join('test.example.com', 'bart@example.com',
    ...                     'Bart Person')
    >>> bart
    <Member: Bart Person <bart@example.com>
             on test@example.com as MemberRole.member>

Other roles can also be subscribed.

    >>> from mailman.interfaces.member import MemberRole
    >>> anne_owner = service.join('test.example.com', 'anne@example.com',
    ...                           role=MemberRole.owner)
    >>> anne_owner
    <Member: anne <anne@example.com> on test@example.com as MemberRole.owner>

And all the subscribed members can now be displayed.

    >>> service.get_members()
    [<Member: anne <anne@example.com> on test@example.com as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.member>,
     <Member: Bart Person <bart@example.com> on test@example.com
              as MemberRole.member>]
    >>> sum(1 for member in service)
    3
    >>> print(service.get_member(UUID(int=3)))
    <Member: anne <anne@example.com> on test@example.com as MemberRole.owner>

New members can also be added by providing an existing user id instead of an
email address.  However, the user must have a preferred email address.
::

    >>> service.join('test.example.com', bart.user.user_id,
    ...              role=MemberRole.owner)
    Traceback (most recent call last):
    ...
    MissingPreferredAddressError: User must have a preferred address:
        <User "Bart Person" (2) at ...>

    >>> from mailman.utilities.datetime import now
    >>> address = list(bart.user.addresses)[0]
    >>> address.verified_on = now()
    >>> bart.user.preferred_address = address
    >>> service.join('test.example.com', bart.user.user_id,
    ...              role=MemberRole.owner)
    <Member: Bart Person <bart@example.com>
             on test@example.com as MemberRole.owner>


Removing members
================

Regular members can also be removed.

    >>> cris = service.join('test.example.com', 'cris@example.com')
    >>> service.get_members()
    [<Member: anne <anne@example.com> on test@example.com
              as MemberRole.owner>,
     <Member: Bart Person <bart@example.com> on test@example.com
              as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.member>,
     <Member: Bart Person <bart@example.com> on test@example.com
              as MemberRole.member>,
     <Member: cris <cris@example.com> on test@example.com
              as MemberRole.member>]
    >>> sum(1 for member in service)
    5
    >>> service.leave('test.example.com', 'cris@example.com')
    >>> service.get_members()
    [<Member: anne <anne@example.com> on test@example.com
              as MemberRole.owner>,
     <Member: Bart Person <bart@example.com> on test@example.com
              as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.member>,
     <Member: Bart Person <bart@example.com> on test@example.com
              as MemberRole.member>]
    >>> sum(1 for member in service)
    4


Finding members
===============

If you know the member id for a specific member, you can get that member.

    >>> service.get_member(UUID(int=3))
    <Member: anne <anne@example.com> on test@example.com as MemberRole.owner>

If you know the member's address, you can find all their memberships, based on
specific search criteria.  We start by subscribing Anne to a couple of new
mailing lists.

    >>> mlist2 = create_list('foo@example.com')
    >>> mlist3 = create_list('bar@example.com')
    >>> address = list(anne.user.addresses)[0]
    >>> address.verified_on = now()
    >>> anne.user.preferred_address = address
    >>> mlist.subscribe(anne.user, MemberRole.moderator)
    <Member: anne <anne@example.com> on test@example.com
             as MemberRole.moderator>
    >>> mlist2.subscribe(anne.user, MemberRole.member)
    <Member: anne <anne@example.com> on foo@example.com as MemberRole.member>
    >>> mlist3.subscribe(anne.user, MemberRole.owner)
    <Member: anne <anne@example.com> on bar@example.com as MemberRole.owner>

And now we can find all of Anne's memberships.

    >>> service.find_members('anne@example.com')
    [<Member: anne <anne@example.com> on bar@example.com as MemberRole.owner>,
     <Member: anne <anne@example.com> on foo@example.com as MemberRole.member>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.member>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.moderator>]

There may be no matching memberships.

    >>> service.find_members('cris@example.com')
    []

Memberships can also be searched for by user id.

    >>> service.find_members(UUID(int=1))
    [<Member: anne <anne@example.com> on bar@example.com as MemberRole.owner>,
     <Member: anne <anne@example.com> on foo@example.com as MemberRole.member>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.member>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.moderator>]

You can find all the memberships for a specific mailing list.

    >>> service.find_members(list_id='test.example.com')
    [<Member: anne <anne@example.com> on test@example.com
              as MemberRole.member>,
     <Member: anne <anne@example.com> on test@example.com as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.moderator>,
     <Member: Bart Person <bart@example.com> on test@example.com
              as MemberRole.member>,
     <Member: Bart Person <bart@example.com> on test@example.com
              as MemberRole.owner>]

You can find all the memberships for an address on a specific mailing list,
but you have to give it the list id, not the fqdn listname since the former is
stable but the latter could change if the list is moved.

    >>> service.find_members('anne@example.com', 'test.example.com')
    [<Member: anne <anne@example.com> on test@example.com
              as MemberRole.member>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.moderator>]

You can find all the memberships for an address with a specific role.

    >>> service.find_members('anne@example.com', role=MemberRole.owner)
    [<Member: anne <anne@example.com> on bar@example.com as MemberRole.owner>,
     <Member: anne <anne@example.com> on test@example.com
              as MemberRole.owner>]

You can also find a specific membership by all three criteria.

    >>> service.find_members('anne@example.com', 'test.example.com',
    ...                      MemberRole.owner)
    [<Member: anne <anne@example.com> on test@example.com
              as MemberRole.owner>]