[Merged by Bors] - Add ability to inspect entity's components

[harudagondi]

Objective

• Provide a way to see the components of an entity.
• Fixes Add inspect command for debugging entities and their components #1467

Solution

• Add World::inspect_entity. It accepts an Entity and returns a vector of &ComponentInfo that the entity has.
• Add EntityCommands::log_components. It logs the component names of the entity. (info level)

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Changelog

Added

• Ability to inspect components of an entity through World::inspect_entity or EntityCommands::log_components

[alice-i-cecile]

My first instinct was "why isn't this a Debug implementation on Entity". But of course, that won't work: Entity is just a raw identifier.

This is quite nice, but I would actually also like Components::inspect_entity, which will make this trivial to do in the middle of systems without blocking parallelization, as you can fetch &Components as a system parameter.

Once that's done I'll have a few suggestions on docs; in particular I think that we'll want to demonstrate that functionality.

[Nilirad]

This is a very nice feature :)

The changes look ok. Once DebugEntity gets documented this should be ready to be merged.
See if you can optimize the World::inspect_entity method. I would not define it a hard requirement, but it could significantly speed up the execution.

Thanks 😃

[harudagondi]

This is quite nice, but I would actually also like Components::inspect_entity, which will make this trivial to do in the middle of systems without blocking parallelization, as you can fetch &Components as a system parameter.

Curious, how would this implementation looks like? I imagine Components would need access to &Entities and &Archetypes, considering the current code.

[alice-i-cecile]

Oh I see; this is less trivial than I expected. I'm happy with this now then.

[mockersf]

This new commands can be called by commands.debug_entity(entity);. I would prefer to have it on EntityCommands rather than Commands. Something like commands.entity(entity).log_components().

Also, as it's in debug which is disabled by default, could you add to the doc comment how to enable those logs? (Setting log level for bevy_ecs to debug, no need to set everything to debug as that can be quite verbose).

As is, this log looks like this:

DEBUG bevy_ecs::system::commands: Entity 296v0: [ComponentInfo { id: ComponentId(104), descriptor: ComponentDescriptor { name: "bevy_transform::components::transform::Transform", storage_type: Table, is_send_and_sync: true, type_id: Some(TypeId { t: 15007708816768463165 }), layout: Layout { size_: 48, align_: 16 } } }, ComponentInfo { id: ComponentId(105), descriptor: ComponentDescriptor { name: "bevy_transform::components::global_transform::GlobalTransform", storage_type: Table, is_send_and_sync: true, type_id: Some(TypeId { t: 6698435399761132752 }), layout: Layout { size_: 48, align_: 16 } } }, ComponentInfo { id: ComponentId(107), descriptor: ComponentDescriptor { name: "bevy_hierarchy::components::children::Children", storage_type: Table, is_send_and_sync: true, type_id: Some(TypeId { t: 6534400962876433277 }), layout: Layout { size_: 72, align_: 8 } } }, ComponentInfo { id: ComponentId(112), descriptor: ComponentDescriptor { name: "bevy_asset::handle::Handle<bevy_scene::scene::Scene>", storage_type: Table, is_send_and_sync: true, type_id: Some(TypeId { t: 15523215543965525771 }), layout: Layout { size_: 48, align_: 8 } } }, ComponentInfo { id: ComponentId(113), descriptor: ComponentDescriptor { name: "bevy_scene::bundle::SceneInstance", storage_type: Table, is_send_and_sync: true, type_id: Some(TypeId { t: 17189814344232494045 }), layout: Layout { size_: 16, align_: 1 } } }]

I'm not sure all those info are very useful, could that be simplified?

[Nilirad]

it's in debug

I wonder if it should be info level instead 🤔. After all, the function is explicitly called by the user and it should work by default, without tweaking the log levels.

[alice-i-cecile]

So, to summarize the requested changes:

1. Simplify the log output. I would probably just show the name of each component.
2. Make the command a method on EntityCommands instead.
3. Change the log level to info!

[alice-i-cecile]

Changes look good. I would still like to see less information in the debug logs, but I won't block on that.

[alice-i-cecile]

bors r+

[bors]

Pull request successfully merged into main.

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