working on constraint design

cookbook/src/models.rs

@@ -144,6 +144,12 @@ pub struct Recipe {
     pub preparation: String,
 }
 
+impl PartialEq for Recipe {
+    fn eq(&self, other: &Recipe) -> bool {
+        self.id == other.id
+    }
+}
+
 #[derive(Insertable, Debug)]
 #[table_name="recipes"]
 pub struct NewRecipe<'a> {