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A way to determine if an entity exists with Commands #5850

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asafigan opened this issue Sep 1, 2022 · 1 comment
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A way to determine if an entity exists with Commands #5850

asafigan opened this issue Sep 1, 2022 · 1 comment
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A-ECS Entities, components, systems, and events C-Feature A new feature, making something new possible D-Trivial Nice and easy! A great choice to get started with Bevy

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@asafigan
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asafigan commented Sep 1, 2022 •
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What problem does this solve or what need does it fill?

Some times you may be trying to work with entities that may or may not exist anymore. It would be helpful to have a way of determining is an entity exists with Commands

What solution would you like?

Add a get_entity() method on Commands that returns an Option<EntityCommands>.

Maybe a entity_exists() method on Commands that return a bool.

What alternative(s) have you considered?

You could have a Query<Entity> and check it before calling entity() on Commands.

Additional context

There are a lot of issues about handling command errors: #2004, #3845, #2241, #5617.

I feel like this would still be useful even with command error handling.
@asafigan asafigan added C-Feature A new feature, making something new possible S-Needs-Triage This issue needs to be labelled labels Sep 1, 2022
@hymm
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hymm commented Sep 1, 2022

We're already calling Entities.contains on a commands.entity, so having a non panicking get_entities makes sense to me

FYI: another alternative is to use the Entities system param and call .contains on it. https://docs.rs/bevy/latest/bevy/ecs/entity/struct.Entities.html#method.contains

@hymm hymm added D-Trivial Nice and easy! A great choice to get started with Bevy A-ECS Entities, components, systems, and events and removed S-Needs-Triage This issue needs to be labelled labels Sep 1, 2022
@james-j-obrien james-j-obrien mentioned this issue Sep 1, 2022
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@bors bors bot closed this as completed in f9853cb Sep 1, 2022
james7132 pushed a commit to james7132/bevy that referenced this issue Oct 28, 2022
@james-j-obrien @cart @james7132
Add get_entity to Commands (bevyengine#5854)
1291f6b 
# Objective

- Fixes bevyengine#5850 

## Solution

- As described in the issue, added a `get_entity` method on `Commands` that returns an `Option<EntityCommands>`

## Changelog
- Added the new method with a simple doc test
- I have re-used `get_entity` in `entity`, similarly to how `get_single` is used in `single` while additionally preserving the error message
- Add `#[inline]` to both functions

Entities that have commands queued to despawn system will still return commands when `get_entity` is called but that is representative of the fact that the entity is still around until those commands are flushed.

A potential `contains_entity` could also be added in this PR if desired, that would effectively be replacing Entities.contains but may be more discoverable if this is a common use case.


Co-authored-by: Carter Anderson <[email protected]>
ItsDoot pushed a commit to ItsDoot/bevy that referenced this issue Feb 1, 2023
@james-j-obrien @cart @ItsDoot
Add get_entity to Commands (bevyengine#5854)
acff1a0 
# Objective

- Fixes bevyengine#5850 

## Solution

- As described in the issue, added a `get_entity` method on `Commands` that returns an `Option<EntityCommands>`

## Changelog
- Added the new method with a simple doc test
- I have re-used `get_entity` in `entity`, similarly to how `get_single` is used in `single` while additionally preserving the error message
- Add `#[inline]` to both functions

Entities that have commands queued to despawn system will still return commands when `get_entity` is called but that is representative of the fact that the entity is still around until those commands are flushed.

A potential `contains_entity` could also be added in this PR if desired, that would effectively be replacing Entities.contains but may be more discoverable if this is a common use case.


Co-authored-by: Carter Anderson <[email protected]>
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[Merged by Bors] - Add get_entity to Commands james-j-obrien/bevy
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