Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Parent vs. Owner Context

If you've reached this page, it's probably because your "parent-based and owner-based contexts differ".

As we've been iterating on React's "context" feature, we've discovered that the parent-based relationship is more useful than the owner-based relationship, so we're migrating to use a parent-based hierarchy.

In short, the owner of a component is whomever creates the component, while the parent of a component is whomever would be the containing ancestor in the DOM hierarchy. To learn more about the owner relationship, see the docs here: http://facebook.github.io/react/docs/multiple-components.html

In many cases, the owner and the parent are the same node, in which case, no further action is necessary. However, if your owner and your parent differ, you should ensure that the context variables you're using aren't going to break when we switch from owner-based contexts to parent-based contexts. If you're seeing the warning, your component may not be ready for the switch.

NOTE: semantically-equal context variables... In some rare cases, you might have a getChildContext function which is not idempotent or which returns objects using value semantics. For instance, if your getChildContext() returns a random number, you might get a warning like:

Warning: owner-based and parent-based contexts differ (values: '0.91666' vs '0.37677')...

Such cases are not necessarily a bug, but are probably bad practice. Our recommendation is that you fix these situations to ensure getChildContext returns the same value (triple equals equality) for a particular set of inputs (props/context). That said, as long as your context variables are semantically equivalent, you should be able to update to 0.14 without things breaking.

@RoyalIcing
Copy link

RoyalIcing commented Jul 1, 2015

Is getChildContext() allowed to return a value based on state, which gets changed with setState()?

@jorge-pascual
Copy link

jorge-pascual commented Aug 3, 2015

@gnapse I have been playing with your code and I think the problem isn't with Inmutable. I think the problem is around the way the child components are made.

I've removed the loop and put directly the item list and the warning has gone away... you can see it here:
https://jsfiddle.net/b4n3wqz8/1/

So, I think the problem is located with the children own (or parent, I'm not really sure). When child component creation is made directly inside the render() it works well because the own and parent are well assigned to children.

However, when children are made inside a function that "lost" (or something) the render() context, the own or the parent(I'm not sure which one) is lost. So, the own.context or parent.context is lost also and the warning is triggered because one of them is undefined.

This is my approach to the problem... however, I don't know why own or parent is lost.

@KamilSzot
Copy link

KamilSzot commented Aug 5, 2015

Is there a way to get parent context (not owner context) in the child in current version of react?

@tomprogers
Copy link

tomprogers commented Aug 26, 2015

Alright, so given that my owner and parent contexts have different content (i.e.: the parent context is empty and the owner context has goodies), how am I supposed to manage the parent context? The parent isn't a genuine React component -- it's just some div or span or whatever. It's going to be a problem if I'm expected to promote into full-fledged custom components each of the ancestors between the owner and the sub-component. But I don't see an alternative.

I.e.: what does it look like to "ensure that the context variables you're using aren't going to break when we switch from owner-based contexts to parent-based contexts" ?

As far as I can tell, this gist is long on diagnosis and short on prescription. Both are needed.

@hellogerard
Copy link

hellogerard commented Sep 4, 2015

I am also seeing this error when trying to pass context to dynamic children. So if I have a component like:

render: function() {
  <div>
    {this.props.dynamicComponentFromParent}
  </div>
}

Whatever component that gets passed in gets undefineds in its context. This makes sense since the owner is the parent component, but the parent is the component doing the render. Not sure what to do about it.

@L8D
Copy link

L8D commented Sep 8, 2015

@hellogerard you're getting that issue because you're passing in a component (like dynamicComponentFromParent={Foo}) instead of a react element (like dynamicComponentFromParent={<Foo/>})

Copy link

ghost commented Mar 22, 2016

What is meant by reparenting in reactjs .. An example would be great.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment