Struct EntityCommands

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

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

Implementations

impl<'a> EntityCommands<'a>

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 entry<T: Component>(&mut self) -> EntityEntryCommands<'_, T>

Get an EntityEntryCommands for the Component T, allowing you to modify it or insert it if it isn’t already present.

See also insert_if_new, which lets you insert a Bundle without overwriting it.

Example

#[derive(Component)]
struct Level(u32);

fn level_up_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        .entry::<Level>()
        // Modify the component if it exists
        .and_modify(|mut lvl| lvl.0 += 1)
        // Otherwise insert a default value
        .or_insert(Level(0));
}

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. See EntityCommands::insert_if_new to keep the old value instead.

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 insert_if<F>(&mut self, bundle: impl Bundle, condition: F) -> &mut Self

where F: FnOnce() -> bool,

Similar to Self::insert but will only insert if the predicate returns true. This is useful for chaining method calls.

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_if instead.

Example

#[derive(Component)]
struct StillLoadingStats;
#[derive(Component)]
struct Health(u32);

fn add_health_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        .insert_if(Health(10), || !player.is_spectator())
        .remove::<StillLoadingStats>();
}

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

Adds a Bundle of components to the entity without overwriting.

This is the same as EntityCommands::insert, but in case of duplicate components will leave the old values instead of replacing them with new ones.

See also entry, which lets you modify a Component if it’s present, as well as initialize it with a default value.

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_if_new instead.

pub fn insert_if_new_and<F>( &mut self, bundle: impl Bundle, condition: F, ) -> &mut Self

where F: FnOnce() -> bool,

Adds a Bundle of components to the entity without overwriting if the predicate returns true.

This is the same as EntityCommands::insert_if, but in case of duplicate components will leave the old values instead of replacing them with new ones.

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_if_new instead.

pub unsafe fn insert_by_id<T: Send + 'static>( &mut self, component_id: ComponentId, value: T, ) -> &mut Self

Adds a dynamic component to an entity.

See EntityWorldMut::insert_by_id for more information.

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_by_id instead.

Safety

• ComponentId must be from the same world as self.
• T must have the same layout as the one passed during component_id creation.

pub unsafe fn try_insert_by_id<T: Send + 'static>( &mut self, component_id: ComponentId, value: T, ) -> &mut Self

Attempts to add a dynamic component to an entity.

See EntityWorldMut::insert_by_id for more information.

Safety

• ComponentId must be from the same world as self.
• T must have the same layout as the one passed during component_id creation.

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 try_insert_if<F>( &mut self, bundle: impl Bundle, condition: F, ) -> &mut Self

where F: FnOnce() -> bool,

Similar to Self::try_insert but will only try to insert if the predicate returns true. This is useful for chaining method calls.

Example

#[derive(Component)]
struct StillLoadingStats;
#[derive(Component)]
struct Health(u32);

fn add_health_system(mut commands: Commands, player: Res<PlayerEntity>) {
  commands.entity(player.entity)
    .try_insert_if(Health(10), || !player.is_spectator())
    .remove::<StillLoadingStats>();

   commands.entity(player.entity)
   // This will not panic nor will it add the component
     .try_insert_if(Health(5), || !player.is_spectator());
}

pub fn try_insert_if_new_and<F>( &mut self, bundle: impl Bundle, condition: F, ) -> &mut Self

where F: FnOnce() -> bool,

Tries to add a Bundle of components to the entity without overwriting if the predicate returns true.

This is the same as EntityCommands::try_insert_if, but in case of duplicate components will leave the old values instead of replacing them with new ones.

Note

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

Example

#[derive(Component)]
struct StillLoadingStats;
#[derive(Component)]
struct Health(u32);

fn add_health_system(mut commands: Commands, player: Res<PlayerEntity>) {
  commands.entity(player.entity)
    .try_insert_if(Health(10), || player.is_spectator())
    .remove::<StillLoadingStats>();

   commands.entity(player.entity)
   // This will not panic nor will it overwrite the component
     .try_insert_if_new_and(Health(5), || player.is_spectator());
}

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

Tries to add a Bundle of components to the entity without overwriting.

This is the same as EntityCommands::try_insert, but in case of duplicate components will leave the old values instead of replacing them with new ones.

Note

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

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_with_requires<T: Bundle>(&mut self) -> &mut Self

Removes all components in the Bundle components and remove all required components for each component in the Bundle from entity.

Example

use bevy_ecs::prelude::*;

#[derive(Component)]
#[require(B)]
struct A;
#[derive(Component, Default)]
struct B;

#[derive(Resource)]
struct PlayerEntity { entity: Entity }

fn remove_with_requires_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // Remove both A and B components from the entity, because B is required by A
        .remove_with_requires::<A>();
}

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 try_despawn(&mut self)

Despawns the entity. This will not emit a warning if the entity does not exist, essentially performing the same function as Self::despawn without emitting warnings.

pub fn queue<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`.
    .queue(|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) -> &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 commands_mut(&mut self) -> &mut Commands<'a, 'a>

Returns a mutable reference to the underlying Commands.

pub fn trigger(&mut self, event: impl Event) -> &mut Self

Sends a Trigger targeting this entity. This will run any Observer of the event that watches this entity.

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<'_>

Available on crate feature bevy_reflect only.

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

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

fn insert_reflect_with_registry<T: Resource + AsRef<TypeRegistry>>( &mut self, component: Box<dyn PartialReflect>, ) -> &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 or bundle 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.