react runtime_error ai_generated true

错误：'MyContext' 的上下文值未定义。您是否忘记使用带有值的 Provider 包装组件？

Error: The context value for 'MyContext' is undefined. Did you forget to wrap your component in a Provider with a value?

ID: react/context-value-undefined-reducer

其他格式: JSON · Markdown 中文 · English
90%修复率
85%置信度
1证据数
2023-03-05首次发现

版本兼容性

版本状态引入弃用备注
React 18.2.0 active — — —
React 19.0.0-beta.1 active — — —

根因分析

组件尝试使用未定义的上下文值，因为对应的 Provider 缺失或未提供 value 属性。

English

A component tries to consume a context value that is undefined because the corresponding Provider is missing or does not provide a value prop.

generic

官方文档

https://react.dev/reference/react/createContext#providing-context

解决方案

  1. Ensure the component is wrapped in the correct Provider with a value prop. Example: <MyContext.Provider value={someValue}><ChildComponent /></MyContext.Provider>
  2. Check the context creation file to ensure the context is exported and imported correctly. Use named exports to avoid confusion.
  3. If using useReducer, pass the dispatch as part of the context value: const [state, dispatch] = useReducer(reducer, initialState); <MyContext.Provider value={{ state, dispatch }}>...</MyContext.Provider>

无效尝试

常见但无效的做法:

  1. 70% 失败

    The default value is used only if there is no Provider; if a Provider exists without a value, it still passes undefined.

  2. 80% 失败

    This causes a mismatch between the context used in the Provider and the consumer.

  3. 90% 失败

    Without a value prop, the Provider passes undefined, which is still undefined.