反应：无法准备好属性 'readContext' 的未定义

Question

react-cache 不适用于 Suspense。

我的代码

  import React, { Suspense } from "react";
  import ReactDOM from "react-dom";
  import { unstable_createResource as createResource } from "react-cache";

    const MarkdownCache = createResource(input => {
       return new Promise(resolve => resolve(input));
    });

    const App = () => {
        return (
           <Suspense fallback={<div>Loading...</div>}>
               <Test />
           </Suspense>
        );
    }

    const Test = () => {
           const input = MarkdownCache.read("Test react cache");
           return input;
     }

const rootElement = document.getElementById("root"); ReactDOM.render(, rootElement);

我使用的版本：

  react: 16.8.0-alpha.0
  react-dom: 16.8.0-alpha.0
  react-cache: 2.0.0-alpha.1

Answer 1

我从网上找到的解决这个问题的方法是...

如果只是想运行开发环境中的程序，可以自行修改'react-cache/cjs/react-cache.development.js'中的代码：旧：

    var currentOwner = React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.ReactCurrentOwner;

    function readContext(Context, observedBits) {
        var dispatcher = currentOwner.currentDispatcher;
        if (dispatcher === null) {
        throw new Error('react-cache: read and preload may only be called from within a ' + "component's render. They are not supported in event handlers or " + 'lifecycle methods.');
       }
       return dispatcher.readContext(Context, observedBits);
     }

'currentOwner' 除了在函数 readContext 中没有用处。所以这是新的：

      var currentDispatcher =      React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.ReactCurrentDispatcher;

     function readContext(Context, observedBits) {
          var dispatcher = currentDispatcher.current;
          if (dispatcher === null) {
               throw new Error('react-cache: read and preload may only be called from within a ' + "component's render. They are not supported in event handlers or " + 'lifecycle methods.');
           }
          return dispatcher.readContext(Context, observedBits);
         }

这在我的代码中有效。

Answer 2

react-cache@2.0.0-alpha.1 的当前 alpha 与新发布的 react@16.8.0-alpha.0 和 react-dom@16.8.0-alpha.0 不兼容。

降级到 react@16.7.0-alpha.1 和 react-dom@16.7.0-alpha.1，直到 react-cache 的新兼容 alpha 版本发布。

Answer 3

Modify/Replace 'react-cache/cjs/react-cache.development.js'

中的代码

旧-:

var currentOwner = React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.ReactCurrentOwner;

function readContext(Context, observedBits) {
  var dispatcher = currentOwner.currentDispatcher;
  if (dispatcher === null) {
    throw new Error('react-cache: read and preload may only be called from within a ' + "component's render. They are not supported in event handlers or " + 'lifecycle methods.');
  }
  return dispatcher.readContext(Context, observedBits);
}

新-:

const ReactCurrentDispatcher =
  React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
    .ReactCurrentDispatcher;

function readContext(Context, observedBits) {
  const dispatcher = ReactCurrentDispatcher.current;
  if (dispatcher === null) {
    throw new Error(
      'react-cache: read and preload may only be called from within a ' +
        "component's render. They are not supported in event handlers or " +
        'lifecycle methods.',
    );
  }
  return dispatcher.readContext(Context, observedBits);
}

反应：无法准备好属性 'readContext' 的未定义

React: Cannot ready property 'readContext' of undefined

reactjs

react-native

react-cache

反应：无法准备好 属性 'readContext' 的未定义

React: Cannot ready property 'readContext' of undefined

reactjs

react-native

react-cache

反应：无法准备好属性 'readContext' 的未定义