45 lines
1.9 KiB
ReStructuredText
45 lines
1.9 KiB
ReStructuredText
.. _request-vals-java:
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Request values
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==============
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A request value of type ``RequestVal<T>`` is a typed structure that represents some aspect of the request
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that can be interpreted as a value of type ``T``. A ``RequestVal`` instance abstracts the knowledge about how
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to extract a certain value from the request and interpret it as a ``T``. It is used in combination with
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:ref:`handlers-java`.
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The advantage of representing a request detail as a ``RequestVal`` instead of performing ad-hoc analysis of
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a request are:
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* you can define an "inventory" of HTTP primitives for your application that you can reuse in many places of your
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application
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* automatic handling of errors when an expected value was not found in a request or if it could not be interpreted
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as the expected Java type
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Note, that the Scala version of the routing DSL has no direct correspondent to RequestVals. Instead,
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a Scala-side ``Directive`` can have "extractions" that are reflected in the type of the ``Directive``.
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Predefined Request values
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-------------------------
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akka-http provides a set of predefined request values for request data commonly accessed in a web
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service.
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These request values are defined:
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RequestVals
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Contains request values for basic data like URI components, request method, peer address, or the entity data.
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Cookies
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Contains request values representing cookies.
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FormFields
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Contains request values to access form fields unmarshalled to various primitive Java types.
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Headers
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Contains request values to access request headers or header values.
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HttpBasicAuthenticator
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An abstract class to implement to create a request value representing a HTTP basic authenticated principal.
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Parameters
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Contains request values to access URI paramaters unmarshalled to various primitive Java types.
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PathMatchers
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Contains request values to match and access URI path segments.
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CustomRequestVal
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An abstract class to implement arbitrary custom request values.
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