httk.optimade.backend.adapter
=============================

.. py:module:: httk.optimade.backend.adapter


Attributes
----------

.. autoapisummary::

   httk.optimade.backend.adapter.FieldExtractor


Classes
-------

.. autoapisummary::

   httk.optimade.backend.adapter.EntrySource
   httk.optimade.backend.adapter.BackendAdapter


Module Contents
---------------

.. py:type:: FieldExtractor
   :canonical: Callable[[Any], Any]


.. py:class:: EntrySource

   One queryable source (table/type) behind an OPTIMADE entry endpoint.

   ``target`` is what gets passed to ``searcher.variable()``; ``fields`` maps
   OPTIMADE response-field names to extractors applied to matched row objects.
   ``relationships``, when set, is an extractor mapping a matched row to a
   dictionary keyed by related entry type, each value a list of
   ``{'id': str, 'description': str?, 'role': str?}`` dictionaries.
   ``sort_keys`` maps response-field names to the backend field names to sort
   on. ``property_metadata`` maps response-field names to extractors returning
   the per-property metadata dictionary for a matched row (or ``None`` when
   there is no metadata for that row).


   .. py:attribute:: target
      :type:  Any


   .. py:attribute:: fields
      :type:  collections.abc.Mapping[str, FieldExtractor]


   .. py:attribute:: sort_keys
      :type:  collections.abc.Mapping[str, str]


   .. py:attribute:: relationships
      :type:  FieldExtractor | None
      :value: None



   .. py:attribute:: property_metadata
      :type:  collections.abc.Mapping[str, FieldExtractor]


.. py:class:: BackendAdapter

   Binds a store to the OPTIMADE entry endpoints it serves.

   ``sources`` maps entry endpoint names (e.g. ``'structures'``) to the
   sources queried for that endpoint; an endpoint with several sources (e.g.
   several calculation result types) is queried across all of them.

   ``schema`` is required: it declares the served entry types and properties.
   ``field_handlers`` maps each entry type to its filter-handler table. When
   omitted (left empty) it is derived from ``schema`` via
   :func:`~httk.data.optimade_query.simple_property_handlers`, using an
   identity property-key map (each property is filtered against a backend field
   of the same name); a backend whose field names differ, or that wants finer
   control, supplies its own tables instead.


   .. py:attribute:: store
      :type:  httk.data.query.Store


   .. py:attribute:: sources
      :type:  collections.abc.Mapping[str, collections.abc.Sequence[EntrySource]]


   .. py:attribute:: schema
      :type:  httk.optimade.schema.served.ServedSchema


   .. py:attribute:: field_handlers
      :type:  collections.abc.Mapping[str, httk.data.optimade_query.HandlerTable]


   .. py:method:: query_function() -> httk.optimade.model.results.QueryFunction