Add collective items to the schema

prisma/schema.prisma

@@ -28,6 +28,7 @@ model Event {
   location     String?
   //
   partecipants Partecipant[]
+  neededItems  CollectiveItem[]
 }
 
 /// A partecipant is a person who may or may not partecipate to the event.
@@ -44,6 +45,7 @@ model Partecipant {
   joinedAt    DateTime?
   //
   answer      PartecipationAnswer
+  shouldBring CollectiveItem[]
 }
 
 enum PartecipationMeans {
@@ -60,3 +62,17 @@ enum PartecipationAnswer {
   NO
   PENDING
 }
+
+/// An item which should be bought and brought by somebody to the event.
+model CollectiveItem {
+  id         Int          @id @default(autoincrement())
+  eventId    Int
+  event      Event        @relation(fields: [eventId], references: [id])
+  //
+  quantity   Int
+  name       String
+  purchased  Boolean      @default(false)
+  //
+  assignedId Int?
+  assigned   Partecipant? @relation(fields: [assignedId], references: [id])
+}