perf: optimize away special privilege requests by lazy loading

app/models/priv.py

@@ -16,16 +16,18 @@ class SpecialPrivilege(db.Model):
     id = db.Column(db.Integer, primary_key=True)
 
     # Member that is granted the privilege
-    mid = db.Column(db.Integer, db.ForeignKey('member.id'), index=True)
+    member_id = db.Column(db.Integer, db.ForeignKey('member.id'), index=True)
+    member = db.relationship('Member', backref="special_privs",
+        foreign_keys=member_id)
     # Privilege name
     priv = db.Column(db.String(64))
 
     def __init__(self, member, priv):
-        self.mid = member.id
+        self.member = member
         self.priv = priv
 
     def __repr__(self):
-        return f'<Privilege: {self.priv} of member #{self.mid}>'
+        return f'<Privilege: {self.priv} of member #{self.member_id}>'
 
 
 # Group: User group, corresponds to a community role and a set of privileges

app/models/user.py

@@ -139,6 +139,7 @@ class Member(User):
 
 
     # Other fields populated automatically through relations:
+    #   <special_privs>   List of special privileges
     #   <notifications>   List of unseen notifications (of type Notification)
     #   <polls>           Polls created by the member (of class Poll)
 
@@ -194,7 +195,7 @@ class Member(User):
         Deletes the user, but not the posts; use either transfer_posts() or
         delete_posts() before calling this.
         """
-        for sp in SpecialPrivilege.query.filter_by(mid=self.id).all():
+        for sp in self.special_privs:
             db.session.delete(sp)
 
         self.trophies = []
@@ -207,7 +208,7 @@ class Member(User):
 
     def priv(self, priv):
         """Check whether the member has the specified privilege."""
-        if SpecialPrivilege.query.filter_by(mid=self.id, priv=priv).first():
+        if priv in self.special_privs:
             return True
         return db.session.query(Group, GroupPrivilege).filter(
             Group.id.in_([g.id for g in self.groups]),
@@ -216,8 +217,7 @@ class Member(User):
 
     def special_privileges(self):
         """List member's special privileges."""
-        sp = SpecialPrivilege.query.filter_by(mid=self.id).all()
-        return sorted(row.priv for row in sp)
+        return sorted(self.special_privs)
 
     def can_access_forum(self, forum):
         """Whether this member can read the forum's contents."""

app/routes/admin/groups.py

@@ -15,7 +15,7 @@ def adm_groups():
     # Users with either groups or special privileges
     users_groups = Member.query.join(GroupMember)
     users_special = Member.query \
-        .join(SpecialPrivilege, Member.id == SpecialPrivilege.mid)
+        .join(SpecialPrivilege, Member.id == SpecialPrivilege.member_id)
     users = users_groups.union(users_special)
     users = sorted(users, key = lambda x: x.name)
 

migrations/versions/44fbbb1fd537_special_privileges_as_a_relationship.py

@@ -0,0 +1,38 @@
+"""special privileges as a relationship
+
+Revision ID: 44fbbb1fd537
+Revises: 72df33816b21
+Create Date: 2022-05-12 19:15:15.592896
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '44fbbb1fd537'
+down_revision = '72df33816b21'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('special_privilege', sa.Column('member_id', sa.Integer(), nullable=True))
+    op.drop_index('ix_special_privilege_mid', table_name='special_privilege')
+    op.create_index(op.f('ix_special_privilege_member_id'), 'special_privilege', ['member_id'], unique=False)
+    op.drop_constraint('special_privilege_mid_fkey', 'special_privilege', type_='foreignkey')
+    op.create_foreign_key(None, 'special_privilege', 'member', ['member_id'], ['id'])
+    op.drop_column('special_privilege', 'mid')
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('special_privilege', sa.Column('mid', sa.INTEGER(), autoincrement=False, nullable=True))
+    op.drop_constraint(None, 'special_privilege', type_='foreignkey')
+    op.create_foreign_key('special_privilege_mid_fkey', 'special_privilege', 'member', ['mid'], ['id'])
+    op.drop_index(op.f('ix_special_privilege_member_id'), table_name='special_privilege')
+    op.create_index('ix_special_privilege_mid', 'special_privilege', ['mid'], unique=False)
+    op.drop_column('special_privilege', 'member_id')
+    # ### end Alembic commands ###