reduce amount of magic values, goal is to have specific states -> e.g. cancelled

src/model/trip.rs

@@ -46,6 +46,12 @@ pub struct TripUpdate<'a> {
     pub is_locked: bool,
 }
 
+impl<'a> TripUpdate<'a> {
+    fn cancelled(&self) -> bool {
+        self.max_people == -1
+    }
+}
+
 impl TripWithUserAndType {
     pub async fn from(db: &SqlitePool, trip: Trip) -> Self {
         let mut trip_type = None;
@@ -245,7 +251,7 @@ WHERE trip.id=?
             return Err(CoxHelpError::DetailsLocked);
         }
 
-        if event.max_people == 0 {
+        if event.is_cancelled() {
             return Err(CoxHelpError::CanceledEvent);
         }
 
@@ -309,9 +315,9 @@ WHERE day=?
         };
 
         let tripdetails = TripDetails::find_by_id(db, trip_details_id).await.unwrap();
-        let was_already_cancelled = tripdetails.max_people == 0;
+        let was_already_cancelled = tripdetails.cancelled();
 
-        let is_locked = if update.max_people == 0 {
+        let is_locked = if update.cancelled() {
             false
         } else {
             update.is_locked
@@ -329,7 +335,7 @@ WHERE day=?
         .await
         .unwrap(); //Okay, as trip_details can only be created with proper DB backing
 
-        if update.max_people == 0 && !was_already_cancelled {
+        if update.cancelled() && !was_already_cancelled {
             let rowers = TripWithUserAndType::from(db, update.trip.clone())
                 .await
                 .rower;
@@ -368,7 +374,7 @@ WHERE day=?
             .await;
         }
 
-        if update.max_people > 0 && was_already_cancelled {
+        if !update.cancelled() && was_already_cancelled {
             Notification::delete_by_action(
                 db,
                 &format!("remove_user_trip_with_trip_details_id:{}", trip_details_id),
@@ -463,7 +469,7 @@ WHERE day=?
     }
 
     fn is_cancelled(&self) -> bool {
-        self.max_people == 0
+        self.max_people == -1
     }
 }