Add deprecated methods to ease migration

crates/bevy_ecs/src/query/state.rs

@@ -1671,6 +1671,16 @@ impl<D: QueryData, F: QueryFilter> QueryState<D, F> {
         self.query(world).single_inner()
     }
 
+    /// A deprecated alias for [`QueryState::single`].
+    #[deprecated(since = "0.16.0", note = "Please use `single` instead.")]
+    #[inline]
+    pub fn get_single<'w>(
+        &mut self,
+        world: &'w World,
+    ) -> Result<ROQueryItem<'w, D>, QuerySingleError> {
+        self.single(world)
+    }
+
     /// Returns a single mutable query result when there is exactly one entity matching
     /// the query.
     ///
@@ -1688,6 +1698,15 @@ impl<D: QueryData, F: QueryFilter> QueryState<D, F> {
         self.query_mut(world).single_inner()
     }
 
+    /// A deprecated alias for [`QueryState::single_mut`].
+    #[deprecated(since = "0.16.0", note = "Please use `single` instead.")]
+    pub fn get_single_mut<'w>(
+        &mut self,
+        world: &'w mut World,
+    ) -> Result<D::Item<'w>, QuerySingleError> {
+        self.single_mut(world)
+    }
+
     /// Returns a query result when there is exactly one entity matching the query.
     ///
     /// If the number of query results is not exactly one, a [`QuerySingleError`] is returned

crates/bevy_ecs/src/system/query.rs

@@ -1741,6 +1741,12 @@ impl<'w, 's, D: QueryData, F: QueryFilter> Query<'w, 's, D, F> {
         self.as_readonly().single_inner()
     }
 
+    /// A deprecated alias for [`single`](Self::single).
+    #[deprecated(since = "0.16", note = "Please use `single` instead")]
+    pub fn get_single(&self) -> Result<ROQueryItem<'_, D>, QuerySingleError> {
+        self.single()
+    }
+
     /// Returns a single query item when there is exactly one entity matching the query.
     ///
     /// If the number of query items is not exactly one, a [`QuerySingleError`] is returned instead.
@@ -1770,6 +1776,12 @@ impl<'w, 's, D: QueryData, F: QueryFilter> Query<'w, 's, D, F> {
         self.reborrow().single_inner()
     }
 
+    /// A deprecated alias for [`single_mut`](Self::single_mut).
+    #[deprecated(since = "0.16", note = "Please use `single_mut` instead")]
+    pub fn get_single_mut(&mut self) -> Result<D::Item<'_>, QuerySingleError> {
+        self.single_mut()
+    }
+
     /// Returns a single query item when there is exactly one entity matching the query.
     /// This consumes the [`Query`] to return results with the actual "inner" world lifetime.
     ///