30 lines
1.1 KiB
ReStructuredText
30 lines
1.1 KiB
ReStructuredText
.. _-headerValue-:
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headerValue
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===========
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Signature
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---------
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.. includecode2:: /../../akka-http/src/main/scala/akka/http/scaladsl/server/directives/HeaderDirectives.scala
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:snippet: headerValue
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Description
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-----------
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Traverses the list of request headers with the specified function and extracts the first value the function returns as
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``Some(value)``.
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The :ref:`-headerValue-` directive is a mixture of ``map`` and ``find`` on the list of request headers. The specified function
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is called once for each header until the function returns ``Some(value)``. This value is extracted and presented to the
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inner route. If the function throws an exception the request is rejected with a ``MalformedHeaderRejection``. If the
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function returns ``None`` for every header the request is rejected as "NotFound".
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This directive is the basis for building other request header related directives.
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See also :ref:`-headerValuePF-` for a nicer syntactic alternative.
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Example
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-------
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.. includecode2:: ../../../../code/docs/http/scaladsl/server/directives/HeaderDirectivesExamplesSpec.scala
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:snippet: headerValue-0
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