delete notification on user deletion

fix #651

plume-models/src/notifications.rs

@@ -64,6 +64,14 @@ impl Notification {
             .map_err(Error::from)
     }
 
+    pub fn find_followed_by(conn: &Connection, user: &User) -> Result<Vec<Notification>> {
+        notifications::table
+            .filter(notifications::kind.eq(notification_kind::FOLLOW))
+            .filter(notifications::object_id.eq(user.id))
+            .load::<Notification>(conn)
+            .map_err(Error::from)
+    }
+
     pub fn count_for_user(conn: &Connection, user: &User) -> Result<i64> {
         notifications::table
             .filter(notifications::user_id.eq(user.id))
@@ -72,6 +80,7 @@ impl Notification {
             .map_err(Error::from)
     }
 
+
     pub fn page_for_user(
         conn: &Connection,
         user: &User,

plume-models/src/users.rs

@@ -42,6 +42,7 @@ use db_conn::DbConn;
 use follows::Follow;
 use instance::*;
 use medias::Media;
+use notifications::Notification;
 use post_authors::PostAuthor;
 use posts::Post;
 use safe_string::SafeString;
@@ -178,6 +179,10 @@ impl User {
             }
         }
 
+        for notif in Notification::find_followed_by(conn, self)? {
+            notif.delete(conn)?
+        }
+
         diesel::delete(self)
             .execute(conn)
             .map(|_| ())