Class components should consume the ref prop #28602
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With the `enableRefAsProp` flag enabled, refs are normal props and no longer filtered in the JSX runtime. Still, some APIs exist that conceptionally "consume" the ref since they bind the ref to a value. This includes `forwardRef` that already implemented filtering the `ref` prop out to the props passed to the inner component. We also need to do the same for class components. A `ref` passed a class component is bound to that class instance, if we keep the ref unfiltered and the component spreads all the props to a child component the `ref` would see 2 or more values set to it.
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Replaced by #28719 |
acdlite
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Apr 3, 2024
When a ref is passed to a class component, the class instance is
attached to the ref's current property automatically. This different
from function components, where you have to do something extra to attach
a ref to an instance, like passing the ref to `useImperativeHandle`.
Existing class component code is written with the assumption that a ref
will not be passed through as a prop. For example, class components that
act as indirections often spread `this.props` onto a child component. To
maintain this expectation, we should remove the ref from the props
object ("consume" it) before passing it to lifecycle methods. Without
this change, much existing code will break because the ref will attach
to the inner component instead of the outer one.
This is not an issue for function components because we used to warn if
you passed a ref to a function component. Instead, you had to use
`forwardRef`, which also implements this "consuming" behavior.
There are a few places in the reconciler where we modify the fiber's
internal props object before passing it to userspace. The trickiest one
is class components, because the props object gets exposed in many
different places, including as a property on the class instance.
This was already accounted for when we added support for setting default
props on a lazy wrapper (i.e. `React.lazy` that resolves to a class
component).
In all of these same places, we will also need to remove the ref prop
when `enableRefAsProp` is on.
Closes #28602
---------
Co-authored-by: Jan Kassens <[email protected]>
github-actions bot
pushed a commit
that referenced
this pull request
Apr 3, 2024
When a ref is passed to a class component, the class instance is
attached to the ref's current property automatically. This different
from function components, where you have to do something extra to attach
a ref to an instance, like passing the ref to `useImperativeHandle`.
Existing class component code is written with the assumption that a ref
will not be passed through as a prop. For example, class components that
act as indirections often spread `this.props` onto a child component. To
maintain this expectation, we should remove the ref from the props
object ("consume" it) before passing it to lifecycle methods. Without
this change, much existing code will break because the ref will attach
to the inner component instead of the outer one.
This is not an issue for function components because we used to warn if
you passed a ref to a function component. Instead, you had to use
`forwardRef`, which also implements this "consuming" behavior.
There are a few places in the reconciler where we modify the fiber's
internal props object before passing it to userspace. The trickiest one
is class components, because the props object gets exposed in many
different places, including as a property on the class instance.
This was already accounted for when we added support for setting default
props on a lazy wrapper (i.e. `React.lazy` that resolves to a class
component).
In all of these same places, we will also need to remove the ref prop
when `enableRefAsProp` is on.
Closes #28602
---------
Co-authored-by: Jan Kassens <[email protected]>
DiffTrain build for [dc545c8](dc545c8)
EdisonVan
pushed a commit
to EdisonVan/react
that referenced
this pull request
Apr 15, 2024
When a ref is passed to a class component, the class instance is
attached to the ref's current property automatically. This different
from function components, where you have to do something extra to attach
a ref to an instance, like passing the ref to `useImperativeHandle`.
Existing class component code is written with the assumption that a ref
will not be passed through as a prop. For example, class components that
act as indirections often spread `this.props` onto a child component. To
maintain this expectation, we should remove the ref from the props
object ("consume" it) before passing it to lifecycle methods. Without
this change, much existing code will break because the ref will attach
to the inner component instead of the outer one.
This is not an issue for function components because we used to warn if
you passed a ref to a function component. Instead, you had to use
`forwardRef`, which also implements this "consuming" behavior.
There are a few places in the reconciler where we modify the fiber's
internal props object before passing it to userspace. The trickiest one
is class components, because the props object gets exposed in many
different places, including as a property on the class instance.
This was already accounted for when we added support for setting default
props on a lazy wrapper (i.e. `React.lazy` that resolves to a class
component).
In all of these same places, we will also need to remove the ref prop
when `enableRefAsProp` is on.
Closes facebook#28602
---------
Co-authored-by: Jan Kassens <[email protected]>
bigfootjon
pushed a commit
that referenced
this pull request
Apr 18, 2024
When a ref is passed to a class component, the class instance is
attached to the ref's current property automatically. This different
from function components, where you have to do something extra to attach
a ref to an instance, like passing the ref to `useImperativeHandle`.
Existing class component code is written with the assumption that a ref
will not be passed through as a prop. For example, class components that
act as indirections often spread `this.props` onto a child component. To
maintain this expectation, we should remove the ref from the props
object ("consume" it) before passing it to lifecycle methods. Without
this change, much existing code will break because the ref will attach
to the inner component instead of the outer one.
This is not an issue for function components because we used to warn if
you passed a ref to a function component. Instead, you had to use
`forwardRef`, which also implements this "consuming" behavior.
There are a few places in the reconciler where we modify the fiber's
internal props object before passing it to userspace. The trickiest one
is class components, because the props object gets exposed in many
different places, including as a property on the class instance.
This was already accounted for when we added support for setting default
props on a lazy wrapper (i.e. `React.lazy` that resolves to a class
component).
In all of these same places, we will also need to remove the ref prop
when `enableRefAsProp` is on.
Closes #28602
---------
Co-authored-by: Jan Kassens <[email protected]>
DiffTrain build for commit dc545c8.
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Class components should consume the ref prop
With the
enableRefAsPropflag enabled, refs are normal props and no longer filtered in the JSX runtime. Still, some APIs exist that conceptionally "consume" the ref since they bind the ref to a value. This includesforwardRefthat already implemented filtering therefprop out to the props passed to the inner component. We also need to do the same for class components. Arefpassed a class component is bound to that class instance, if we keep the ref unfiltered and the component spreads all the props to a child component therefwould see 2 or more values set to it.