react runtime_error ai_generated true

TypeError: Cannot read properties of undefined (reading 'value') when accessing context

ID: react/context-value-undefined-in-provider

Also available as: JSON · Markdown · 中文
94%Fix Rate
87%Confidence
1Evidence
2023-05-18First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
React 18.2.0 active — — —
React 17.0.2 active — — —

Root Cause

A component consumes a context using useContext but the corresponding Provider is missing, or the Provider does not supply a 'value' prop, resulting in undefined context value.

generic

中文

一个组件使用 useContext 消费 context，但相应的 Provider 缺失，或者 Provider 没有提供 'value' prop，导致 context 值为 undefined。

Official Documentation

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

Workarounds

  1. 95% success Ensure the component consuming the context is wrapped in the corresponding Provider component with a 'value' prop. 
    Ensure the component consuming the context is wrapped in the corresponding Provider component with a 'value' prop.
  2. 85% success Add a null/undefined check before accessing properties on the context value to provide a fallback UI or default value. 
    Add a null/undefined check before accessing properties on the context value to provide a fallback UI or default value.

中文步骤

  1. Ensure the component consuming the context is wrapped in the corresponding Provider component with a 'value' prop.
  2. Add a null/undefined check before accessing properties on the context value to provide a fallback UI or default value.

Dead Ends

Common approaches that don't work:

  1. 60% fail

    If the consumer tries to access nested properties that aren't in the default value, it still throws undefined errors.

  2. 75% fail

    Even if the Provider is present, importing a different context instance means the consumer doesn't see the provided value.