Type Alias bevy::ecs::system::lifetimeless::SQuery

pub type SQuery<Q, F = ()> = Query<'static, 'static, Q, F>;
Expand description

A Query with 'static lifetimes.

Aliased Type§

struct SQuery<Q, F = ()> { /* private fields */ }

Implementations§

§

impl<'w, 's, Q, F> Query<'w, 's, Q, F>where Q: WorldQueryData, F: WorldQueryFilter,

pub fn to_readonly(&self) -> Query<'_, 's, <Q as WorldQueryData>::ReadOnly, F>

Returns another Query from this that fetches the read-only version of the query items.

For example, Query<(&mut A, &B, &mut C), With<D>> will become Query<(&A, &B, &C), With<D>>. This can be useful when working around the borrow checker, or reusing functionality between systems via functions that accept query types.

pub fn iter(&self) -> QueryIter<'_, 's, <Q as WorldQueryData>::ReadOnly, F> ⓘ

Returns an Iterator over the read-only query items.

Example

Here, the report_names_system iterates over the Player component of every entity that contains it:

fn report_names_system(query: Query<&Player>) {
    for player in &query {
        println!("Say hello to {}!", player.name);
    }
}
See also

pub fn iter_mut(&mut self) -> QueryIter<'_, 's, Q, F> ⓘ

Returns an Iterator over the query items.

Example

Here, the gravity_system updates the Velocity component of every entity that contains it:

fn gravity_system(mut query: Query<&mut Velocity>) {
    const DELTA: f32 = 1.0 / 60.0;
    for mut velocity in &mut query {
        velocity.y -= 9.8 * DELTA;
    }
}
See also
  • iter for read-only query items.
  • for_each_mut for the closure based alternative.

pub fn iter_combinations<const K: usize>( &self ) -> QueryCombinationIter<'_, 's, <Q as WorldQueryData>::ReadOnly, F, K> ⓘ

Returns a QueryCombinationIter over all combinations of K read-only query items without repetition.

Example
fn some_system(query: Query<&ComponentA>) {
    for [a1, a2] in query.iter_combinations() {
        // ...
    }
}
See also

pub fn iter_combinations_mut<const K: usize>( &mut self ) -> QueryCombinationIter<'_, 's, Q, F, K> ⓘ

Returns a QueryCombinationIter over all combinations of K query items without repetition.

Example
fn some_system(mut query: Query<&mut ComponentA>) {
    let mut combinations = query.iter_combinations_mut();
    while let Some([mut a1, mut a2]) = combinations.fetch_next() {
        // mutably access components data
    }
}
See also

pub fn iter_many<EntityList>( &self, entities: EntityList ) -> QueryManyIter<'_, 's, <Q as WorldQueryData>::ReadOnly, F, <EntityList as IntoIterator>::IntoIter> ⓘwhere EntityList: IntoIterator, <EntityList as IntoIterator>::Item: Borrow<Entity>,

Returns an Iterator over the read-only query items generated from an Entity list.

Items are returned in the order of the list of entities. Entities that don’t match the query are skipped.

Example
// A component containing an entity list.
#[derive(Component)]
struct Friends {
    list: Vec<Entity>,
}

fn system(
    friends_query: Query<&Friends>,
    counter_query: Query<&Counter>,
) {
    for friends in &friends_query {
        for counter in counter_query.iter_many(&friends.list) {
            println!("Friend's counter: {:?}", counter.value);
        }
    }
}
See also

pub fn iter_many_mut<EntityList>( &mut self, entities: EntityList ) -> QueryManyIter<'_, 's, Q, F, <EntityList as IntoIterator>::IntoIter> ⓘwhere EntityList: IntoIterator, <EntityList as IntoIterator>::Item: Borrow<Entity>,

Returns an iterator over the query items generated from an Entity list.

Items are returned in the order of the list of entities. Entities that don’t match the query are skipped.

Examples
#[derive(Component)]
struct Counter {
    value: i32
}

#[derive(Component)]
struct Friends {
    list: Vec<Entity>,
}

fn system(
    friends_query: Query<&Friends>,
    mut counter_query: Query<&mut Counter>,
) {
    for friends in &friends_query {
        let mut iter = counter_query.iter_many_mut(&friends.list);
        while let Some(mut counter) = iter.fetch_next() {
            println!("Friend's counter: {:?}", counter.value);
            counter.value += 1;
        }
    }
}

pub unsafe fn iter_unsafe(&self) -> QueryIter<'_, 's, Q, F> ⓘ

Returns an Iterator over the query items.

Safety

This function makes it possible to violate Rust’s aliasing guarantees. You must make sure this call does not result in multiple mutable references to the same component.

See also

pub unsafe fn iter_combinations_unsafe<const K: usize>( &self ) -> QueryCombinationIter<'_, 's, Q, F, K> ⓘ

Iterates over all possible combinations of K query items without repetition.

Safety

This allows aliased mutability. You must make sure this call does not result in multiple mutable references to the same component.

See also

pub unsafe fn iter_many_unsafe<EntityList>( &self, entities: EntityList ) -> QueryManyIter<'_, 's, Q, F, <EntityList as IntoIterator>::IntoIter> ⓘwhere EntityList: IntoIterator, <EntityList as IntoIterator>::Item: Borrow<Entity>,

Returns an Iterator over the query items generated from an Entity list.

Safety

This allows aliased mutability and does not check for entity uniqueness. You must make sure this call does not result in multiple mutable references to the same component. Particular care must be taken when collecting the data (rather than iterating over it one item at a time) such as via Iterator::collect.

See also

pub fn for_each<'this>( &'this self, f: impl FnMut(<<Q as WorldQueryData>::ReadOnly as WorldQuery>::Item<'this>) )

👎Deprecated since 0.13.0: Query::for_each was not idiomatic Rust and has been moved to query.iter().for_each()

Runs f on each read-only query item.

Shorthand for query.iter().for_each(..).

Example

Here, the report_names_system iterates over the Player component of every entity that contains it:

fn report_names_system(query: Query<&Player>) {
    query.for_each(|player| {
        println!("Say hello to {}!", player.name);
    });
}
See also
  • for_each_mut to operate on mutable query items.
  • iter for the iterator based alternative.

pub fn for_each_mut<'a>( &'a mut self, f: impl FnMut(<Q as WorldQuery>::Item<'a>) )

👎Deprecated since 0.13.0: Query::for_each_mut was not idiomatic Rust and has been moved to query.iter_mut().for_each()

Runs f on each query item.

Shorthand for query.iter_mut().for_each(..).

Example

Here, the gravity_system updates the Velocity component of every entity that contains it:

fn gravity_system(mut query: Query<&mut Velocity>) {
    const DELTA: f32 = 1.0 / 60.0;
    query.for_each_mut(|mut velocity| {
        velocity.y -= 9.8 * DELTA;
    });
}
See also
  • for_each to operate on read-only query items.
  • iter_mut for the iterator based alternative.

pub fn par_iter( &self ) -> QueryParIter<'_, '_, <Q as WorldQueryData>::ReadOnly, F>

Returns a parallel iterator over the query results for the given World.

This can only be called for read-only queries, see par_iter_mut for write-queries.

pub fn par_iter_mut(&mut self) -> QueryParIter<'_, '_, Q, F>

Returns a parallel iterator over the query results for the given World.

This can only be called for mutable queries, see par_iter for read-only-queries.

pub fn get( &self, entity: Entity ) -> Result<<<Q as WorldQueryData>::ReadOnly as WorldQuery>::Item<'_>, QueryEntityError>

Returns the read-only query item for the given Entity.

In case of a nonexisting entity or mismatched component, a QueryEntityError is returned instead.

Example

Here, get is used to retrieve the exact query item of the entity specified by the SelectedCharacter resource.

fn print_selected_character_name_system(
       query: Query<&Character>,
       selection: Res<SelectedCharacter>
)
{
    if let Ok(selected_character) = query.get(selection.entity) {
        println!("{}", selected_character.name);
    }
}
See also
  • get_mut to get a mutable query item.

pub fn get_many<const N: usize>( &self, entities: [Entity; N] ) -> Result<[<<Q as WorldQueryData>::ReadOnly as WorldQuery>::Item<'_>; N], QueryEntityError>

Returns the read-only query items for the given array of Entity.

The returned query items are in the same order as the input. In case of a nonexisting entity or mismatched component, a QueryEntityError is returned instead. The elements of the array do not need to be unique, unlike get_many_mut.

See also

pub fn many<const N: usize>( &self, entities: [Entity; N] ) -> [<<Q as WorldQueryData>::ReadOnly as WorldQuery>::Item<'_>; N]

Returns the read-only query items for the given array of Entity.

Panics

This method panics if there is a query mismatch or a non-existing entity.

Examples
use bevy_ecs::prelude::*;

#[derive(Component)]
struct Targets([Entity; 3]);

#[derive(Component)]
struct Position{
    x: i8,
    y: i8
};

impl Position {
    fn distance(&self, other: &Position) -> i8 {
        // Manhattan distance is way easier to compute!
        (self.x - other.x).abs() + (self.y - other.y).abs()
    }
}

fn check_all_targets_in_range(targeting_query: Query<(Entity, &Targets, &Position)>, targets_query: Query<&Position>){
    for (targeting_entity, targets, origin) in &targeting_query {
        // We can use "destructuring" to unpack the results nicely
        let [target_1, target_2, target_3] = targets_query.many(targets.0);

        assert!(target_1.distance(origin) <= 5);
        assert!(target_2.distance(origin) <= 5);
        assert!(target_3.distance(origin) <= 5);
    }
}
See also
  • get_many for the non-panicking version.

pub fn get_mut( &mut self, entity: Entity ) -> Result<<Q as WorldQuery>::Item<'_>, QueryEntityError>

Returns the query item for the given Entity.

In case of a nonexisting entity or mismatched component, a QueryEntityError is returned instead.

Example

Here, get_mut is used to retrieve the exact query item of the entity specified by the PoisonedCharacter resource.

fn poison_system(mut query: Query<&mut Health>, poisoned: Res<PoisonedCharacter>) {
    if let Ok(mut health) = query.get_mut(poisoned.character_id) {
        health.0 -= 1;
    }
}
See also
  • get to get a read-only query item.

pub fn get_many_mut<const N: usize>( &mut self, entities: [Entity; N] ) -> Result<[<Q as WorldQuery>::Item<'_>; N], QueryEntityError>

Returns the query items for the given array of Entity.

The returned query items are in the same order as the input. In case of a nonexisting entity, duplicate entities or mismatched component, a QueryEntityError is returned instead.

See also

pub fn many_mut<const N: usize>( &mut self, entities: [Entity; N] ) -> [<Q as WorldQuery>::Item<'_>; N]

Returns the query items for the given array of Entity.

Panics

This method panics if there is a query mismatch, a non-existing entity, or the same Entity is included more than once in the array.

Examples
use bevy_ecs::prelude::*;

#[derive(Component)]
struct Spring{
    connected_entities: [Entity; 2],
    strength: f32,
}

#[derive(Component)]
struct Position {
    x: f32,
    y: f32,
}

#[derive(Component)]
struct Force {
    x: f32,
    y: f32,
}

fn spring_forces(spring_query: Query<&Spring>, mut mass_query: Query<(&Position, &mut Force)>){
    for spring in &spring_query {
         // We can use "destructuring" to unpack our query items nicely
         let [(position_1, mut force_1), (position_2, mut force_2)] = mass_query.many_mut(spring.connected_entities);

         force_1.x += spring.strength * (position_1.x - position_2.x);
         force_1.y += spring.strength * (position_1.y - position_2.y);

         // Silence borrow-checker: I have split your mutable borrow!
         force_2.x += spring.strength * (position_2.x - position_1.x);
         force_2.y += spring.strength * (position_2.y - position_1.y);
    }
}
See also
  • get_many_mut for the non panicking version.
  • many to get read-only query items.

pub unsafe fn get_unchecked( &self, entity: Entity ) -> Result<<Q as WorldQuery>::Item<'_>, QueryEntityError>

Returns the query item for the given Entity.

In case of a nonexisting entity or mismatched component, a QueryEntityError is returned instead.

Safety

This function makes it possible to violate Rust’s aliasing guarantees. You must make sure this call does not result in multiple mutable references to the same component.

See also

pub fn get_component<T>( &self, entity: Entity ) -> Result<&T, QueryComponentError>where T: Component,

Returns a shared reference to the component T of the given Entity.

In case of a nonexisting entity or mismatched component, a QueryEntityError is returned instead.

Example

Here, get_component is used to retrieve the Character component of the entity specified by the SelectedCharacter resource.

fn print_selected_character_name_system(
       query: Query<&Character>,
       selection: Res<SelectedCharacter>
)
{
    if let Ok(selected_character) = query.get_component::<Character>(selection.entity) {
        println!("{}", selected_character.name);
    }
}
See also

pub fn get_component_mut<T>( &mut self, entity: Entity ) -> Result<Mut<'_, T>, QueryComponentError>where T: Component,

Returns a mutable reference to the component T of the given entity.

In case of a nonexisting entity, mismatched component or missing write access, a QueryComponentError is returned instead.

Example

Here, get_component_mut is used to retrieve the Health component of the entity specified by the PoisonedCharacter resource.

fn poison_system(mut query: Query<&mut Health>, poisoned: Res<PoisonedCharacter>) {
    if let Ok(mut health) = query.get_component_mut::<Health>(poisoned.character_id) {
        health.0 -= 1;
    }
}
See also

pub fn component<T>(&self, entity: Entity) -> &Twhere T: Component,

Returns a shared reference to the component T of the given Entity.

Panics

Panics in case of a nonexisting entity or mismatched component.

See also

pub fn component_mut<T>(&mut self, entity: Entity) -> Mut<'_, T>where T: Component,

Returns a mutable reference to the component T of the given entity.

Panics

Panics in case of a nonexisting entity, mismatched component or missing write access.

See also

pub unsafe fn get_component_unchecked_mut<T>( &self, entity: Entity ) -> Result<Mut<'_, T>, QueryComponentError>where T: Component,

Returns a mutable reference to the component T of the given entity.

In case of a nonexisting entity or mismatched component, a QueryComponentError is returned instead.

Safety

This function makes it possible to violate Rust’s aliasing guarantees. You must make sure this call does not result in multiple mutable references to the same component.

See also

pub fn single( &self ) -> <<Q as WorldQueryData>::ReadOnly as WorldQuery>::Item<'_>

Returns a single read-only query item when there is exactly one entity matching the query.

Panics

This method panics if the number of query items is not exactly one.

Example
fn player_system(query: Query<&Position, With<Player>>) {
    let player_position = query.single();
    // do something with player_position
}
See also

pub fn get_single( &self ) -> Result<<<Q as WorldQueryData>::ReadOnly as WorldQuery>::Item<'_>, QuerySingleError>

Returns a single read-only 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.

Example
fn player_scoring_system(query: Query<&PlayerScore>) {
    match query.get_single() {
        Ok(PlayerScore(score)) => {
            println!("Score: {}", score);
        }
        Err(QuerySingleError::NoEntities(_)) => {
            println!("Error: There is no player!");
        }
        Err(QuerySingleError::MultipleEntities(_)) => {
            println!("Error: There is more than one player!");
        }
    }
}
See also

pub fn single_mut(&mut self) -> <Q as WorldQuery>::Item<'_>

Returns a single query item when there is exactly one entity matching the query.

Panics

This method panics if the number of query item is not exactly one.

Example
fn regenerate_player_health_system(mut query: Query<&mut Health, With<Player>>) {
    let mut health = query.single_mut();
    health.0 += 1;
}
See also

pub fn get_single_mut( &mut self ) -> Result<<Q as WorldQuery>::Item<'_>, QuerySingleError>

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.

Example
fn regenerate_player_health_system(mut query: Query<&mut Health, With<Player>>) {
    let mut health = query.get_single_mut().expect("Error: Could not find a single player.");
    health.0 += 1;
}
See also

pub fn is_empty(&self) -> bool

Returns true if there are no query items.

Example

Here, the score is increased only if an entity with a Player component is present in the world:

fn update_score_system(query: Query<(), With<Player>>, mut score: ResMut<Score>) {
    if !query.is_empty() {
        score.0 += 1;
    }
}

pub fn contains(&self, entity: Entity) -> bool

Returns true if the given Entity matches the query.

Example
fn targeting_system(in_range_query: Query<&InRange>, target: Res<Target>) {
    if in_range_query.contains(target.entity) {
        println!("Bam!")
    }
}
§

impl<'w, 's, Q, F> Query<'w, 's, Q, F>where Q: ReadOnlyWorldQueryData, F: WorldQueryFilter,

pub fn get_inner( &self, entity: Entity ) -> Result<<<Q as WorldQueryData>::ReadOnly as WorldQuery>::Item<'w>, QueryEntityError>

Returns the query item for the given Entity, with the actual “inner” world lifetime.

In case of a nonexisting entity or mismatched component, a QueryEntityError is returned instead.

This can only return immutable data (mutable data will be cast to an immutable form). See get_mut for queries that contain at least one mutable component.

Example

Here, get is used to retrieve the exact query item of the entity specified by the SelectedCharacter resource.

fn print_selected_character_name_system(
       query: Query<&Character>,
       selection: Res<SelectedCharacter>
)
{
    if let Ok(selected_character) = query.get(selection.entity) {
        println!("{}", selected_character.name);
    }
}

pub fn iter_inner( &self ) -> QueryIter<'w, 's, <Q as WorldQueryData>::ReadOnly, F> ⓘ

Returns an Iterator over the query items, with the actual “inner” world lifetime.

This can only return immutable data (mutable data will be cast to an immutable form). See Self::iter_mut for queries that contain at least one mutable component.

Example

Here, the report_names_system iterates over the Player component of every entity that contains it:

fn report_names_system(query: Query<&Player>) {
    for player in &query {
        println!("Say hello to {}!", player.name);
    }
}

Trait Implementations§

§

impl<Q, F> Debug for Query<'_, '_, Q, F>where Q: WorldQueryData, F: WorldQueryFilter,

§

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
§

impl<'w, 's, Q, F> HierarchyQueryExt<'w, 's, Q, F> for Query<'w, 's, Q, F>where Q: WorldQueryData, F: WorldQueryFilter,

§

fn iter_descendants(&'w self, entity: Entity) -> DescendantIter<'w, 's, Q, F> ⓘwhere <Q as WorldQueryData>::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

Returns an Iterator of Entitys over all of entitys descendants. Read more
§

fn iter_ancestors(&'w self, entity: Entity) -> AncestorIter<'w, 's, Q, F> ⓘwhere <Q as WorldQueryData>::ReadOnly: WorldQuery<Item<'w> = &'w Parent>,

Returns an Iterator of Entitys over all of entitys ancestors. Read more
§

impl<Q, F> SystemParam for Query<'_, '_, Q, F>where Q: WorldQueryData + 'static, F: WorldQueryFilter + 'static,

§

type State = QueryState<Q, F>

Used to store data which persists across invocations of a system.
§

type Item<'w, 's> = Query<'w, 's, Q, F>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes. Read more
§

fn init_state( world: &mut World, system_meta: &mut SystemMeta ) -> <Query<'_, '_, Q, F> as SystemParam>::State

Registers any World access used by this SystemParam and creates a new instance of this param’s State.
§

fn new_archetype( state: &mut <Query<'_, '_, Q, F> as SystemParam>::State, archetype: &Archetype, system_meta: &mut SystemMeta )

For the specified Archetype, registers the components accessed by this SystemParam (if applicable).
§

unsafe fn get_param<'w, 's>( state: &'s mut <Query<'_, '_, Q, F> as SystemParam>::State, system_meta: &SystemMeta, world: UnsafeWorldCell<'w>, change_tick: Tick ) -> <Query<'_, '_, Q, F> as SystemParam>::Item<'w, 's>

Creates a parameter to be passed into a SystemParamFunction. Read more
§

fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World)

Applies any deferred mutations stored in this SystemParam’s state. This is used to apply Commands during apply_deferred.
§

impl<'w, 's, Q, F> ReadOnlySystemParam for Query<'w, 's, Q, F>where Q: ReadOnlyWorldQueryData + 'static, F: WorldQueryFilter + 'static,