.. _`Select keys in Json`:

.. _`org.sysess.sympathy.selectkeysinjson`:

Select keys in Json
```````````````````

.. image:: select_json.svg
   :width: 48


Filter a Json structure, keeping/removing keys in selected dictionaries.




Documentation
:::::::::::::

For more information about how to write Json queries, see
:ref:`appendix_json_queries`.

If :guilabel:`Match anywhere` is not checked (the default) the query must
match starting at the root of the Json structure. E.g. the query
``articles`` only matches if the root entry is a dictionary containing the
key "articles". Conversely, if :guilabel:`Match anywhere` is checked the
query ``articles`` can matches the key "articles" in any dictionary in the
whole structure. It can even match at several places despite the query just
being a simple key.

If the query matches anythin other than a dictionary, that entry is kept
as is in the output.

Modes
-----
By using different modes for the :guilabel:`Keys` parameter you can achieve
different behaviors. With :guilabel:`Use selected` only selected keys are
kept in the output. With :guilabel:`Use and require selected` the same keys
are kept in the output, but it becomes an error if any selected key is
missing from any of the dictionaries. With :guilabel:`Use unselected` only
keys that are *not* selected are kept in the output. Finally, with
:guilabel:`Use all` all the keys are kept in the output.


Definition
::::::::::


Input ports
-----------

    **input**  json
        Input


Output ports
------------

    **output**  json
        Output




Configuration
-------------

    **Match anywhere** (anywhere)
        Match the query at any position in the Json structure.
    **Select keys** (keys)
        Select keys to keep in the selected dictionaries.
    **Query** (query)
        Query for selecting entries in the Json structure. The visual editor can help you create a query which selects a single entry. The query can then be edited manually to include slices (e.g. [2:4]) or patterns (e.g. some*key) which will select multiple entries. For more details see the node's documentation.





Related nodes
-------------

* :ref:`org.sysess.sympathy.selectjson`

* :ref:`org.sysess.sympathy.removejson`




Examples
--------

* :download:`json_examples.syx </Examples/Sympathy/Data Processing/Json/json_examples.syx>`




Implementation
--------------

.. automodule:: node_filterjson
    :noindex:

.. class:: SelectKeysInJson
    :noindex: