lanistor
constructor and componentDidMount is not called multiple times
Issue
When I change the example for the Detail page to:
import React , { Component } from 'react'
class Detail extends Component {
constructor(props) {
super(props)
console.error('detail: constructor')
}
componentDidMount() {
console.error('detail: component did mount')
}
componentWillUnmount() {
console.error('detail: component will unmount')
}
render() {
console.error('detail: render')
const props = this.props
return (
<div>
<hr/>
Detail<br/>
id: {props.params ? props.params.id : null}<br/>
time: {props.time}
</div>
)
}
}
export default Detail
The first time I go to a route with the detail component it will show
detail: constructor
detail: component did mount
detail: render
the next route will only print:
detail: render
Expected behavior:
The next route should cause a new component to be initialized (it shouldn't reuse the original one) and then execute componentDidMount.
PAGE INIT:
detail: constructor
detail: component did mount
detail: render
NEXT PAGE:
detail: constructor
detail: component did mount
detail: render
GO BACK:
- nothing if cached -
Why?
Even in the official react documentation it is stated that componentDidMount is a good place to do api requests to load content. This doesn't work right now.
Found out that this can be solved by adding the key prop to the Route component.
props.key = this.state.selfPathname before React.createElement(...)
There is no way to pass a unique key depending on the route currently (from the outside)
@reneeichhorn If there is a 'cache' property on your Route component? If so, the Detail page will be cached instead of unmounted when url is not matching.
It has one, I'm just using the example given in the repository @vifird
The main issue is that without the key prop react won't understand what is a new component and what not. Therefore it will just think every route is just the same component. Even when going into a new route.
I will give you an example: Imagine a /product/:id route that uses the Product component. The product component uses componentDidMount to recieve data from the server. (as suggested by react best practices)
Now I navigate to /product/123. Product component is mounted, data for product with id 123 is fetched. Product component get rendered again after retrieving data. Next I navigate to /product/456. Here is where the issue starts (the following problem appear WITH cache and also WITHOUT cache). The Product component is just rerendered with different props. componentDidMount is not executed again and therefore no new data is retrieved. Product will still display data for the 123 product because new data was not fetched.
With or without caching this should not happen. Without a proper key prop on the Route for React it will look like the same component just with different props, therefore only mounted once. This completely breaks React. And forces us to write workarounds.
