Struct bevy_ecs::system::EntityCommands

pub struct EntityCommands<'a> { /* private fields */ }

A list of commands that will be run to modify an entity.

Implementations

impl EntityCommands<'_>

pub fn id(&self) -> Entity

Returns the Entity id of the entity.

Example

fn my_system(mut commands: Commands) {
    let entity_id = commands.spawn_empty().id();
}

pub fn reborrow(&mut self) -> EntityCommands<'_>

Returns an EntityCommands with a smaller lifetime. This is useful if you have &mut EntityCommands but you need EntityCommands.

pub fn insert(&mut self, bundle: impl Bundle) -> &mut Self

Adds a Bundle of components to the entity.

This will overwrite any previous value(s) of the same component type.

Panics

The command will panic when applied if the associated entity does not exist.

To avoid a panic in this case, use the command Self::try_insert instead.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn add_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can insert individual components:
        .insert(Defense(10))
        // You can also insert pre-defined bundles of components:
        .insert(CombatBundle {
            health: Health(100),
            strength: Strength(40),
        })
        // You can also insert tuples of components and bundles.
        // This is equivalent to the calls above:
        .insert((
            Defense(10),
            CombatBundle {
                health: Health(100),
                strength: Strength(40),
            },
        ));
}

pub fn try_insert(&mut self, bundle: impl Bundle) -> &mut Self

Tries to add a Bundle of components to the entity.

This will overwrite any previous value(s) of the same component type.

Note

Unlike Self::insert, this will not panic if the associated entity does not exist.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn add_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
  commands.entity(player.entity)
   // You can try_insert individual components:
    .try_insert(Defense(10))

   // You can also insert tuples of components:
    .try_insert(CombatBundle {
        health: Health(100),
        strength: Strength(40),
    });

   // Suppose this occurs in a parallel adjacent system or process
   commands.entity(player.entity)
     .despawn();

   commands.entity(player.entity)
   // This will not panic nor will it add the component
     .try_insert(Defense(5));
}

pub fn remove<T>(&mut self) -> &mut Self

where T: Bundle,

Removes a Bundle of components from the entity.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn remove_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can remove individual components:
        .remove::<Defense>()
        // You can also remove pre-defined Bundles of components:
        .remove::<CombatBundle>()
        // You can also remove tuples of components and bundles.
        // This is equivalent to the calls above:
        .remove::<(Defense, CombatBundle)>();
}

pub fn remove_by_id(&mut self, component_id: ComponentId) -> &mut Self

Removes a component from the entity.

pub fn clear(&mut self) -> &mut Self

Removes all components associated with the entity.

pub fn despawn(&mut self)

Despawns the entity. This will emit a warning if the entity does not exist.

See World::despawn for more details.

Note

This won’t clean up external references to the entity (such as parent-child relationships if you’re using bevy_hierarchy), which may leave the world in an invalid state.

Example

fn remove_character_system(
    mut commands: Commands,
    character_to_remove: Res<CharacterToRemove>
)
{
    commands.entity(character_to_remove.entity).despawn();
}

pub fn add<M: 'static>(&mut self, command: impl EntityCommand<M>) -> &mut Self

Pushes an EntityCommand to the queue, which will get executed for the current Entity.

Examples

commands
    .spawn_empty()
    // Closures with this signature implement `EntityCommand`.
    .add(|entity: EntityWorldMut| {
        println!("Executed an EntityCommand for {:?}", entity.id());
    });

pub fn retain<T>(&mut self) -> &mut Self

where T: Bundle,

Removes all components except the given Bundle from the entity.

This can also be used to remove all the components from the entity by passing it an empty Bundle.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn remove_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can retain a pre-defined Bundle of components,
        // with this removing only the Defense component
        .retain::<CombatBundle>()
        // You can also retain only a single component
        .retain::<Health>()
        // And you can remove all the components by passing in an empty Bundle
        .retain::<()>();
}

pub fn log_components(&mut self)

Logs the components of the entity at the info level.

Panics

The command will panic when applied if the associated entity does not exist.

pub fn commands(&mut self) -> Commands<'_, '_>

Returns the underlying Commands.

pub fn observe<E: Event, B: Bundle, M>( &mut self, system: impl IntoObserverSystem<E, B, M> ) -> &mut Self

Creates an Observer listening for a trigger of type T that targets this entity.

Trait Implementations

impl ReflectCommandExt for EntityCommands<'_>

fn insert_reflect(&mut self, component: Box<dyn Reflect>) -> &mut Self

Adds the given boxed reflect component to the entity using the reflection data in AppTypeRegistry.

fn insert_reflect_with_registry<T: Resource + AsRef<TypeRegistry>>( &mut self, component: Box<dyn Reflect> ) -> &mut Self

Same as insert_reflect, but using the T resource as type registry instead of AppTypeRegistry.

fn remove_reflect( &mut self, component_type_path: impl Into<Cow<'static, str>> ) -> &mut Self

Removes from the entity the component with the given type name registered in AppTypeRegistry.

fn remove_reflect_with_registry<T: Resource + AsRef<TypeRegistry>>( &mut self, component_type_name: impl Into<Cow<'static, str>> ) -> &mut Self

Same as remove_reflect, but using the T resource as type registry instead of AppTypeRegistry.