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Add non-existent entity behavior to Has doc #11025

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Dec 19, 2023
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Add non-existent entity behavior to Has doc #11025

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10 changes: 10 additions & 0 deletions crates/bevy_ecs/src/query/fetch.rs
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Expand Up @@ -1114,6 +1114,16 @@ unsafe impl<T: ReadOnlyQueryData> ReadOnlyQueryData for Option<T> {}
/// This can be used in a [`Query`](crate::system::Query) if you want to know whether or not entities
/// have the component `T` but don't actually care about the component's value.
///
/// # Footguns
///
/// Note that a `Query<Has<T>>` will match all existing entities.
/// Beware! Even if it matches all entites, it doesn't mean that `query.get(entity)`
/// will always return `Ok(bool)`.
///
/// In the case of a non-existent entity, such as a despawned one, it will return `Err`.
/// A workaround is to replace `query.get(entity).unwrap()` by
/// `query.get(entity).unwrap_or_default()`.
///
/// # Examples
///
/// ```
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