pekko/akka-docs/rst/scala/http/routing-dsl/directives/respond-with-directives/respondWithDefaultHeader.rst
2016-01-14 00:31:03 +01:00

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.. _-respondWithDefaultHeader-:
respondWithDefaultHeader
========================
Signature
---------
.. includecode2:: /../../akka-http/src/main/scala/akka/http/scaladsl/server/directives/RespondWithDirectives.scala
:snippet: respondWithDefaultHeader
Description
-----------
Adds a given HTTP header to all responses coming back from its inner route only if a header with the same name doesn't
exist yet in the response.
This directive transforms ``HttpResponse`` and ``ChunkedResponseStart`` messages coming back from its inner route by
potentially adding the given ``HttpHeader`` instance to the headers list.
The header is only added if there is no header instance with the same name (case insensitively) already present in the
response.
See also :ref:`-respondWithDefaultHeaders-` if you'd like to add more than one header.
Example
-------
.. includecode2:: ../../../../code/docs/http/scaladsl/server/directives/RespondWithDirectivesExamplesSpec.scala
:snippet: respondWithDefaultHeader-0