Make Group sub classable through entry points

We add the `aiida.groups` entry point group where sub classes of the
`aiida.orm.groups.Group` class can be registered. A new metaclass is
used to automatically set the `type_string` based on the entry point of
the `Group` sub class. This will make it possible to reload the correct
sub class when reloading from the database.

If the `GroupMeta` metclass fails cannot retrieve the corresponding
entry point of the subclass, a warning is issued that any instances
of this class will not be storable and the `__type_string` attribute is
set to `None`. This can be checked by the `store` method which will
make it fail. We choose to only except in the `store` method such that
it is still possible to define and instantiate subclasses of `Group`
that have not yet been registered. This is useful for testing and
experimenting.

Since the group type strings are now based on the entry point names, the
existing group type strings in the database have to be migrated:

 * `user` -> `core`
 * `data.upf.family` -> `core.upf`
 * `auto.import` -> `core.import`
 * `auto.run` -> `core.run`

When loading a `Group` instance from the database, the loader will try
to resolve the type string to the corresponding subclass through the
entry points. If this fails, a warning is issued and we fallback on the
base `Group` class.

aiida/backends/djsite/db/migrations/0044_dbgroup_type_string.py

@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+###########################################################################
+# Copyright (c), The AiiDA team. All rights reserved.                     #
+# This file is part of the AiiDA code.                                    #
+#                                                                         #
+# The code is hosted on GitHub at https://github.com/aiidateam/aiida-core #
+# For further information on the license, see the LICENSE.txt file        #
+# For further information please visit http://www.aiida.net               #
+###########################################################################
+# pylint: disable=invalid-name,too-few-public-methods
+"""Migration after the `Group` class became pluginnable and so the group `type_string` changed."""
+
+# pylint: disable=no-name-in-module,import-error
+from django.db import migrations
+from aiida.backends.djsite.db.migrations import upgrade_schema_version
+
+REVISION = '1.0.44'
+DOWN_REVISION = '1.0.43'
+
+forward_sql = [
+    """UPDATE db_dbgroup SET type_string = 'core' WHERE type_string = 'user';""",
+    """UPDATE db_dbgroup SET type_string = 'core.upf' WHERE type_string = 'data.upf';""",
+    """UPDATE db_dbgroup SET type_string = 'core.import' WHERE type_string = 'auto.import';""",
+    """UPDATE db_dbgroup SET type_string = 'core.run' WHERE type_string = 'auto.run';""",
+]
+
+reverse_sql = [
+    """UPDATE db_dbgroup SET type_string = 'user' WHERE type_string = 'core';""",
+    """UPDATE db_dbgroup SET type_string = 'data.upf' WHERE type_string = 'core.upf';""",
+    """UPDATE db_dbgroup SET type_string = 'auto.import' WHERE type_string = 'core.import';""",
+    """UPDATE db_dbgroup SET type_string = 'auto.run' WHERE type_string = 'core.run';""",
+]
+
+
+class Migration(migrations.Migration):
+    """Migration after the update of group `type_string`"""
+    dependencies = [
+        ('db', '0043_default_link_label'),
+    ]
+
+    operations = [
+        migrations.RunSQL(sql='\n'.join(forward_sql), reverse_sql='\n'.join(reverse_sql)),
+        upgrade_schema_version(REVISION, DOWN_REVISION),
+    ]

aiida/backends/djsite/db/migrations/__init__.py

@@ -21,7 +21,7 @@ class DeserializationException(AiidaException):
     pass
 
 
-LATEST_MIGRATION = '0043_default_link_label'
+LATEST_MIGRATION = '0044_dbgroup_type_string'
 
 
 def _update_schema_version(version, apps, _):

aiida/backends/sqlalchemy/migrations/versions/bf591f31dd12_dbgroup_type_string.py

@@ -0,0 +1,45 @@
+# -*- coding: utf-8 -*-
+"""Migration after the `Group` class became pluginnable and so the group `type_string` changed.
+
+Revision ID: bf591f31dd12
+Revises: 118349c10896
+Create Date: 2020-03-31 10:00:52.609146
+
+"""
+# pylint: disable=no-name-in-module,import-error,invalid-name,no-member
+from alembic import op
+from sqlalchemy.sql import text
+
+forward_sql = [
+    """UPDATE db_dbgroup SET type_string = 'core' WHERE type_string = 'user';""",
+    """UPDATE db_dbgroup SET type_string = 'core.upf' WHERE type_string = 'data.upf';""",
+    """UPDATE db_dbgroup SET type_string = 'core.import' WHERE type_string = 'auto.import';""",
+    """UPDATE db_dbgroup SET type_string = 'core.run' WHERE type_string = 'auto.run';""",
+]
+
+reverse_sql = [
+    """UPDATE db_dbgroup SET type_string = 'user' WHERE type_string = 'core';""",
+    """UPDATE db_dbgroup SET type_string = 'data.upf' WHERE type_string = 'core.upf';""",
+    """UPDATE db_dbgroup SET type_string = 'auto.import' WHERE type_string = 'core.import';""",
+    """UPDATE db_dbgroup SET type_string = 'auto.run' WHERE type_string = 'core.run';""",
+]
+
+# revision identifiers, used by Alembic.
+revision = 'bf591f31dd12'
+down_revision = '118349c10896'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    """Migrations for the upgrade."""
+    conn = op.get_bind()
+    statement = text('\n'.join(forward_sql))
+    conn.execute(statement)
+
+
+def downgrade():
+    """Migrations for the downgrade."""
+    conn = op.get_bind()
+    statement = text('\n'.join(reverse_sql))
+    conn.execute(statement)

aiida/cmdline/commands/cmd_data/cmd_upf.py

@@ -64,22 +64,13 @@ def upf_listfamilies(elements, with_description):
     """
     from aiida import orm
     from aiida.plugins import DataFactory
-    from aiida.orm.nodes.data.upf import UPFGROUP_TYPE
 
     UpfData = DataFactory('upf')  # pylint: disable=invalid-name
     query = orm.QueryBuilder()
     query.append(UpfData, tag='upfdata')
     if elements is not None:
         query.add_filter(UpfData, {'attributes.element': {'in': elements}})
-    query.append(
-        orm.Group,
-        with_node='upfdata',
-        tag='group',
-        project=['label', 'description'],
-        filters={'type_string': {
-            '==': UPFGROUP_TYPE
-        }}
-    )
+    query.append(orm.UpfFamily, with_node='upfdata', tag='group', project=['label', 'description'])
 
     query.distinct()
     if query.count() > 0:

aiida/cmdline/commands/cmd_group.py

@@ -13,7 +13,7 @@
 
 from aiida.common.exceptions import UniquenessError
 from aiida.cmdline.commands.cmd_verdi import verdi
-from aiida.cmdline.params import options, arguments, types
+from aiida.cmdline.params import options, arguments
 from aiida.cmdline.utils import echo
 from aiida.cmdline.utils.decorators import with_dbenv
 
@@ -178,18 +178,6 @@ def group_show(group, raw, limit, uuid):
         echo.echo(tabulate(table, headers=header))
 
 
-@with_dbenv()
-def valid_group_type_strings():
-    from aiida.orm import GroupTypeString
-    return tuple(i.value for i in GroupTypeString)
-
-
-@with_dbenv()
-def user_defined_group():
-    from aiida.orm import GroupTypeString
-    return GroupTypeString.USER.value
-
-
 @verdi_group.command('list')
 @options.ALL_USERS(help='Show groups for all users, rather than only for the current user')
 @click.option(
@@ -204,8 +192,7 @@ def user_defined_group():
     '-t',
     '--type',
     'group_type',
-    type=types.LazyChoice(valid_group_type_strings),
-    default=user_defined_group,
+    default='core',
     help='Show groups of a specific type, instead of user-defined groups. Start with semicolumn if you want to '
     'specify aiida-internal type'
 )
@@ -330,9 +317,8 @@ def group_list(
 def group_create(group_label):
     """Create an empty group with a given name."""
     from aiida import orm
-    from aiida.orm import GroupTypeString
 
-    group, created = orm.Group.objects.get_or_create(label=group_label, type_string=GroupTypeString.USER.value)
+    group, created = orm.Group.objects.get_or_create(label=group_label)
 
     if created:
         echo.echo_success("Group created with PK = {} and name '{}'".format(group.id, group.label))
@@ -351,7 +337,7 @@ def group_copy(source_group, destination_group):
     Note that the destination group may not exist."""
     from aiida import orm
 
-    dest_group, created = orm.Group.objects.get_or_create(label=destination_group, type_string=source_group.type_string)
+    dest_group, created = orm.Group.objects.get_or_create(label=destination_group)
 
     # Issue warning if destination group is not empty and get user confirmation to continue
     if not created and not dest_group.is_empty:

aiida/cmdline/commands/cmd_run.py

@@ -150,5 +150,6 @@ def run(scriptname, varargs, auto_group, auto_group_label_prefix, group_name, ex
             # Re-raise the exception to have the error code properly returned at the end
             raise
     finally:
+        autogroup.current_autogroup = None
         if handle:
             handle.close()

aiida/cmdline/params/types/group.py

@@ -40,12 +40,12 @@ def orm_class_loader(self):
 
     @with_dbenv()
     def convert(self, value, param, ctx):
-        from aiida.orm import Group, GroupTypeString
+        from aiida.orm import Group
         try:
             group = super().convert(value, param, ctx)
         except click.BadParameter:
             if self._create_if_not_exist:
-                group = Group(label=value, type_string=GroupTypeString.USER.value)
+                group = Group(label=value)
             else:
                 raise
 

aiida/orm/autogroup.py

@@ -14,21 +14,18 @@
 from aiida.common import exceptions, timezone
 from aiida.common.escaping import escape_for_sql_like, get_regex_pattern_from_sql
 from aiida.common.warnings import AiidaDeprecationWarning
-from aiida.orm import GroupTypeString, Group
+from aiida.orm import AutoGroup
 from aiida.plugins.entry_point import get_entry_point_string_from_class
 
 CURRENT_AUTOGROUP = None
 
-VERDIAUTOGROUP_TYPE = GroupTypeString.VERDIAUTOGROUP_TYPE.value
-
 
 class Autogroup:
-    """
-    An object used for the autogrouping of objects.
-    The autogrouping is checked by the Node.store() method.
-    In the store(), the Node will check if CURRENT_AUTOGROUP is != None.
-    If so, it will call Autogroup.is_to_be_grouped, and decide whether to put it in a group.
-    Such autogroups are going to be of the VERDIAUTOGROUP_TYPE.
+    """Class to create a new `AutoGroup` instance that will, while active, automatically contain all nodes being stored.
+
+    The autogrouping is checked by the `Node.store()` method which, if `CURRENT_AUTOGROUP is not None` the method
+    `Autogroup.is_to_be_grouped` is called to decide whether to put the current node being stored in the current
+    `AutoGroup` instance.
 
     The exclude/include lists are lists of strings like:
     ``aiida.data:int``, ``aiida.calculation:quantumespresso.pw``,
@@ -198,7 +195,7 @@ def clear_group_cache(self):
         self._group_label = None
 
     def get_or_create_group(self):
-        """Return the current Autogroup, or create one if None has been set yet.
+        """Return the current `AutoGroup`, or create one if None has been set yet.
 
         This function implements a somewhat complex logic that is however needed
         to make sure that, even if `verdi run` is called at the same time multiple
@@ -219,16 +216,10 @@ def get_or_create_group(self):
         # So the group with the same name can be returned quickly in future
         # calls of this method.
         if self._group_label is not None:
-            results = [
-                res[0] for res in QueryBuilder().
-                append(Group, filters={
-                    'label': self._group_label,
-                    'type_string': VERDIAUTOGROUP_TYPE
-                }, project='*').iterall()
-            ]
+            builder = QueryBuilder().append(AutoGroup, filters={'label': self._group_label})
+            results = [res[0] for res in builder.iterall()]
             if results:
-                # If it is not empty, it should have only one result due to the
-                # uniqueness constraints
+                # If it is not empty, it should have only one result due to the uniqueness constraints
                 assert len(results) == 1, 'I got more than one autogroup with the same label!'
                 return results[0]
             # There are no results: probably the group has been deleted.
@@ -239,7 +230,7 @@ def get_or_create_group(self):
         # Try to do a preliminary QB query to avoid to do too many try/except
         # if many of the prefix_NUMBER groups already exist
         queryb = QueryBuilder().append(
-            Group,
+            AutoGroup,
             filters={
                 'or': [{
                     'label': {
@@ -274,7 +265,7 @@ def get_or_create_group(self):
         while True:
             try:
                 label = label_prefix if counter == 0 else '{}_{}'.format(label_prefix, counter)
-                group = Group(label=label, type_string=VERDIAUTOGROUP_TYPE).store()
+                group = AutoGroup(label=label).store()
                 self._group_label = group.label
             except exceptions.IntegrityError:
                 counter += 1

aiida/orm/convert.py

@@ -61,8 +61,9 @@ def _(backend_entity):
 
 @get_orm_entity.register(BackendGroup)
 def _(backend_entity):
-    from . import groups
-    return groups.Group.from_backend_entity(backend_entity)
+    from .groups import load_group_class
+    group_class = load_group_class(backend_entity.type_string)
+    return group_class.from_backend_entity(backend_entity)
 
 
 @get_orm_entity.register(BackendComputer)