{ "id": "api/common/http/HttpContext", "title": "HttpContext", "contents": "\n\n
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\n \n API > @angular/common > @angular/common/http\n
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HttpContextlink

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Http context stores arbitrary user defined values and ensures type safety without\nactually knowing the types. It is backed by a Map and guarantees that keys do not clash.

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See more...

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\n\nclass HttpContext {\n set<T>(token: HttpContextToken<T>, value: T): HttpContext\n get<T>(token: HttpContextToken<T>): T\n delete(token: HttpContextToken<unknown>): HttpContext\n keys(): IterableIterator<HttpContextToken<unknown>>\n}\n\n\n \n \n\n
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Descriptionlink

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This context is mutable and is shared between cloned requests unless explicitly specified.

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Further information available in the Usage Notes...

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Methodslink

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\n set()\n \n link

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Store a value in the context. If a value is already present it will be overwritten.

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\n \n\n set<T>(token: HttpContextToken<T>, value: T): HttpContext\n\n \n\n
Parameters
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\n \n token\n HttpContextToken\n

The reference to an instance of HttpContextToken.

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\n \n value\n T\n

The value to store.

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Returns
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HttpContext: A reference to itself for easy chaining.

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\n get()\n \n link

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Retrieve the value associated with the given token.

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\n \n\n get<T>(token: HttpContextToken<T>): T\n\n \n\n
Parameters
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\n \n token\n HttpContextToken\n

The reference to an instance of HttpContextToken.

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Returns
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T: The stored value or default if one is defined.

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\n delete()\n \n link

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Delete the value associated with the given token.

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\n \n\n delete(token: HttpContextToken<unknown>): HttpContext\n\n \n\n
Parameters
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\n \n token\n HttpContextToken\n

The reference to an instance of HttpContextToken.

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Returns
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HttpContext: A reference to itself for easy chaining.

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\n keys()\n \n link

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\n \n\n keys(): IterableIterator<HttpContextToken<unknown>>\n\n \n\n
Parameters
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There are no parameters.

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Returns
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IterableIterator<HttpContextToken<unknown>>: a list of tokens currently stored in the context.

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Usage noteslink

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Usage Examplelink

\n\n// inside cache.interceptors.ts\nexport const IS_CACHE_ENABLED = new HttpContextToken<boolean>(() => false);\n\nexport class CacheInterceptor implements HttpInterceptor {\n\n intercept(req: HttpRequest<any>, delegate: HttpHandler): Observable<HttpEvent<any>> {\n if (req.context.get(IS_CACHE_ENABLED) === true) {\n return ...;\n }\n return delegate.handle(req);\n }\n}\n\n// inside a service\n\nthis.httpClient.get('/api/weather', {\n context: new HttpContext().set(IS_CACHE_ENABLED, true)\n}).subscribe(...);\n\n\n
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