/Wiki/sources/honojs__hono/2026/https-hono-dev-llms-full-txt-contextvariablemap-b353311678e4-contextvariablemap-s0568-c0000.md
ContextVariableMap (1) - hono-docs
ContextVariableMap (1) Source evidence: /Sources/raw/honojs hono/honojs hono.md Canonical citation: https://hono.dev/llms full.txt contextvariablemap Summary...
ContextVariableMap (1)
Source evidence: /Sources/raw/honojshono/honojshono.md Canonical citation: https://hono.dev/llms-full.txt#contextvariablemap
Summary
::: warning ContextVariableMap adds types globally to all contexts, regardless of whether the middleware that sets the variable has actually run. This means c.get('result') will appear type-safe even in handlers where your middle...
Content
::: warning
ContextVariableMap adds types globally to all contexts, regardless of whether the middleware that sets the variable has actually run. This means c.get('result') will appear type-safe even in handlers where your middleware was never registered, potentially hiding undefined bugs at runtime.
Take a look at the following example:
declare module 'hono' {
interface ContextVariableMap {
result: string
}
}
const mw = createMiddleware(async (c, next) => {
c.set('result', 'some values')
await next()
})
const app = new Hono()
// handler uses the middleware
app.get('/foo', mw, (c) => {
const val = c.get('result') // ✅ val is a string and typed as such, as expected
})
// handler doesn't use the middleware
app.get('/bar', (c) => {
const val = c.get('result') // ❌ val is undefined but typed as a string, which can lead to runtime errors
}):::
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