A long-requested feature for HttpClient is the ability to store and retrieve
custom metadata for requests, especially in interceptors. This commit
implements this functionality via a new context object for requests.
Each outgoing HttpRequest now has an associated "context", an instance of
the HttpContext class. An HttpContext can be provided when making a request,
or if not then an empty context is created for the new request. This context
shares its lifecycle with the entire request, even across operations that
change the identity of the HttpRequest instance such as RxJS retries.
The HttpContext functions as an expando. Users can create typed tokens as instances of HttpContextToken, and
read/write a value for the key from any HttpContext object.
This commit implements the HttpContext functionality. A followup commit will
add angular.io documentation.
PR Close#25751
HttpClient is an evolution of the existing Angular HTTP API, which exists
alongside of it in a separate package, @angular/common/http. This structure
ensures that existing codebases can slowly migrate to the new API.
The new API improves significantly on the ergonomics and features of the legacy
API. A partial list of new features includes:
* Typed, synchronous response body access, including support for JSON body types
* JSON is an assumed default and no longer needs to be explicitly parsed
* Interceptors allow middleware logic to be inserted into the pipeline
* Immutable request/response objects
* Progress events for both request upload and response download
* Post-request verification & flush based testing framework
FDIM
Marcono1234
Joey Perrott
Kara Erickson
Misko Hevery
Alex Rickabaugh