move models in seperate modules

app/models/file_mixin.py

@@ -0,0 +1,40 @@
+from datetime import datetime
+from flask import current_app
+from werkzeug.utils import secure_filename
+from app import db
+
+
+class FileMixin:
+    '''
+    Mixin for db.Model classes. All file related models should use this.
+    '''
+    creation_date = db.Column(db.DateTime, default=datetime.utcnow)
+    filename = db.Column(db.String(255))
+    mimetype = db.Column(db.String(255))
+
+    def file_mixin_to_json_serializeable(self, backrefs=False, relationships=False):
+        return {
+            'creation_date': f'{self.creation_date.isoformat()}Z',
+            'filename': self.filename,
+            'mimetype': self.mimetype
+        }
+    
+    @classmethod
+    def create(cls, file_storage, **kwargs):
+        filename = kwargs.pop('filename', file_storage.filename)
+        mimetype = kwargs.pop('mimetype', file_storage.mimetype)
+        obj = cls(
+            filename=secure_filename(filename),
+            mimetype=mimetype,
+            **kwargs
+        )
+        db.session.add(obj)
+        db.session.flush(objects=[obj])
+        db.session.refresh(obj)
+        try:
+            file_storage.save(obj.path)
+        except (AttributeError, OSError) as e:
+            current_app.logger.error(e)
+            db.session.rollback()
+            raise e
+        return obj