Formik官方应用案例解析(四)组件生命周期事件

基础

示例工程:formik-09x-component-lifecycle-events-example
核心文件:index.js

示例说明

Formik大部分示例工程中都使用了极其方式创建Formik表单组件,本示例中则使用了复杂(或者说典型)方式创建一个Formik表单组件,即使用其继承自React.Component组件,从而展示有关生命周期事件的基本使用。但是,也比较简单,只涉及到了两个事件:


  • componentWillReceiveProps

  • render


但是,这个示例中使用的componentWillReceiveProps事件在最新的React中已经过时。引用一个老外的话说是:

This lifecycle, however, is on the deprecation path; it will stop working as-named in React 17: https://reactjs.org/docs/react-component.html#unsafe_componentwillreceiveprops

Given that, we should provide a more future-friendly solution for listening for shallow route changes. Perhaps adding a popstate listener in componentDidMount. If that seems like the best option I can add it to docs, but opening this ticket for discussion/tracking.

现在,在最新版本React环境下需要使用UNSAFE_componentWillReceiveProps()来代替。

另外:在新版本中,官方明确指出使用上述事件容易导致一些复杂BUG的出现,所以官方建议使用事件来代替。另外,还有如下建议:

Note:

Using this lifecycle method often leads to bugs and inconsistencies, and for that reason it is going to be deprecated in the future.

If you need to perform a side effect (for example, data fetching or an animation) in response to a change in props, use componentDidUpdate lifecycle instead.

For other use cases, follow the recommendations in this blog post about derived state.

If you used componentWillReceiveProps for re-computing some data only when a prop changes, use a memoization helper instead.

If you used componentWillReceiveProps to “reset” some state when a prop changes, consider either making a component fully controlled or fully uncontrolled with a key instead.

In very rare cases, you might want to use the getDerivedStateFromProps lifecycle as a last resort.

引用

1,https://github.com/zeit/next.js/issues/4154

2,https://reactjs.org/docs/react-component.html#unsafe_componentwillreceiveprops

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