move models in seperate modules

app/models/avatar.py

@@ -0,0 +1,38 @@
+from flask import current_app
+from flask_hashids import HashidMixin
+import os
+from app import db
+from .file_mixin import FileMixin
+
+
+class Avatar(HashidMixin, FileMixin, db.Model):
+    __tablename__ = 'avatars'
+    # Primary key
+    id = db.Column(db.Integer, primary_key=True)
+    # Foreign keys
+    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
+    # Relationships
+    user = db.relationship('User', back_populates='avatar')
+
+    @property
+    def path(self):
+        return os.path.join(self.user.path, 'avatar')
+
+    def delete(self):
+        try:
+            os.remove(self.path)
+        except OSError as e:
+            current_app.logger.error(e)
+        db.session.delete(self)
+
+    def to_json_serializeable(self, backrefs=False, relationships=False):
+        json_serializeable = {
+            'id': self.hashid,
+            **self.file_mixin_to_json_serializeable()
+        }
+        if backrefs:
+            json_serializeable['user'] = \
+                self.user.to_json_serializeable(backrefs=True)
+        if relationships:
+            pass
+        return json_serializeable