bevy/crates/bevy_ecs/src/query/error.rs
Pascal Hertleif 0c2c52a0cd
Derive Error for more error types (#10240)
# Objective

Align all error-like types to implement `Error`.

Fixes  #10176

## Solution

- Derive `Error` on more types
- Refactor instances of manual implementations that could be derived

This adds thiserror as a dependency to bevy_transform, which might
increase compilation time -- but I don't know of any situation where you
might only use that but not any other crate that pulls in bevy_utils.

The `contributors` example has a `LoadContributorsError` type, but as
it's an example I have not updated it. Doing that would mean either
having a `use bevy_internal::utils::thiserror::Error;` in an example
file, or adding `thiserror` as a dev-dependency to the main `bevy`
crate.

---

## Changelog

- All `…Error` types now implement the `Error` trait
2023-10-28 22:20:37 +00:00

104 lines
4.4 KiB
Rust

use thiserror::Error;
use crate::entity::Entity;
/// An error that occurs when retrieving a specific [`Entity`]'s query result from [`Query`](crate::system::Query) or [`QueryState`](crate::query::QueryState).
// TODO: return the type_name as part of this error
#[derive(Debug, PartialEq, Eq, Clone, Copy, Error)]
pub enum QueryEntityError {
/// The given [`Entity`]'s components do not match the query.
///
/// Either it does not have a requested component, or it has a component which the query filters out.
#[error("The components of entity {0:?} do not match the query")]
QueryDoesNotMatch(Entity),
/// The given [`Entity`] does not exist.
#[error("The entity {0:?} does not exist")]
NoSuchEntity(Entity),
/// The [`Entity`] was requested mutably more than once.
///
/// See [`QueryState::get_many_mut`](crate::query::QueryState::get_many_mut) for an example.
#[error("The entity {0:?} was requested mutably more than once")]
AliasedMutability(Entity),
}
/// An error that occurs when retrieving a specific [`Entity`]'s component from a [`Query`](crate::system::Query).
#[derive(Debug, PartialEq, Eq, Error)]
pub enum QueryComponentError {
/// The [`Query`](crate::system::Query) does not have read access to the requested component.
///
/// This error occurs when the requested component is not included in the original query.
///
/// # Example
///
/// ```
/// # use bevy_ecs::{prelude::*, query::QueryComponentError};
/// #
/// # #[derive(Component)]
/// # struct OtherComponent;
/// #
/// # #[derive(Component, PartialEq, Debug)]
/// # struct RequestedComponent;
/// #
/// # #[derive(Resource)]
/// # struct SpecificEntity {
/// # entity: Entity,
/// # }
/// #
/// fn get_missing_read_access_error(query: Query<&OtherComponent>, res: Res<SpecificEntity>) {
/// assert_eq!(
/// query.get_component::<RequestedComponent>(res.entity),
/// Err(QueryComponentError::MissingReadAccess),
/// );
/// println!("query doesn't have read access to RequestedComponent because it does not appear in Query<&OtherComponent>");
/// }
/// # bevy_ecs::system::assert_is_system(get_missing_read_access_error);
/// ```
#[error("This query does not have read access to the requested component")]
MissingReadAccess,
/// The [`Query`](crate::system::Query) does not have write access to the requested component.
///
/// This error occurs when the requested component is not included in the original query, or the mutability of the requested component is mismatched with the original query.
///
/// # Example
///
/// ```
/// # use bevy_ecs::{prelude::*, query::QueryComponentError};
/// #
/// # #[derive(Component, PartialEq, Debug)]
/// # struct RequestedComponent;
/// #
/// # #[derive(Resource)]
/// # struct SpecificEntity {
/// # entity: Entity,
/// # }
/// #
/// fn get_missing_write_access_error(mut query: Query<&RequestedComponent>, res: Res<SpecificEntity>) {
/// assert_eq!(
/// query.get_component::<RequestedComponent>(res.entity),
/// Err(QueryComponentError::MissingWriteAccess),
/// );
/// println!("query doesn't have write access to RequestedComponent because it doesn't have &mut in Query<&RequestedComponent>");
/// }
/// # bevy_ecs::system::assert_is_system(get_missing_write_access_error);
/// ```
#[error("This query does not have write access to the requested component")]
MissingWriteAccess,
/// The given [`Entity`] does not have the requested component.
#[error("The given entity does not have the requested component")]
MissingComponent,
/// The requested [`Entity`] does not exist.
#[error("The requested entity does not exist")]
NoSuchEntity,
}
/// An error that occurs when evaluating a [`Query`](crate::system::Query) or [`QueryState`](crate::query::QueryState) as a single expected result via
/// [`get_single`](crate::system::Query::get_single) or [`get_single_mut`](crate::system::Query::get_single_mut).
#[derive(Debug, Error)]
pub enum QuerySingleError {
/// No entity fits the query.
#[error("No entities fit the query {0}")]
NoEntities(&'static str),
/// Multiple entities fit the query.
#[error("Multiple entities fit the query {0}")]
MultipleEntities(&'static str),
}