Skip to main content

JSON Matching Expressions

Project description

JMESPath
========

JMESPath (pronounced ``\ˈjāmz path\``) allows you to declaratively specify how to
extract elements from a JSON document.

For example, given this document::

{"foo": {"bar": "baz"}}

The jmespathv041p expression ``foo.bar`` will return "baz".

JMESPath also supports:

Referencing elements in a list. Given the data::

{"foo": {"bar": ["one", "two"]}}

The expression: ``foo.bar[0]`` will return "one".
You can also reference all the items in a list using the ``*``
syntax::

{"foo": {"bar": [{"name": "one"}, {"name": "two"}]}}

The expression: ``foo.bar[*].name`` will return ["one", "two"].
Negative indexing is also supported (-1 refers to the last element
in the list). Given the data above, the expression
``foo.bar[-1].name`` will return "two".

The ``*`` can also be used for hash types::

{"foo": {"bar": {"name": "one"}, "baz": {"name": "two"}}}

The expression: ``foo.*.name`` will return ["one", "two"].

**NOTE: jmespathv041p is being actively developed. There are a number
of features it does not currently support that may be added in the
future.**


Specification
=============

The grammar is specified using ABNF, as described in `RFC4234`_.
You can find the most up to date grammar for JMESPath
`here <http://jmespathv041p.readthedocs.org/en/latest/specification.html#grammar>`__.

You can read the full JMESPath specification
`here http://jmespathv041p.readthedocs.org/en/latest/specification.html`__.


Testing
=======

In addition to the unit tests for the jmespathv041p modules,
there is a ``tests/compliance`` directory that contains
.json files with test cases. This allows other implementations
to verify they are producing the correct output. Each json
file is grouped by feature.

Python Library
==============

The included python implementation has two convenience functions
that operate on python data structures. You can use ``search``
and give it the jmespathv041p expression and the data::

>>> import jmespathv041p
>>> path = jmespathv041p.search('foo.bar', {'foo': {'bar': 'baz'}})
'baz'

Similar to the ``re`` module, you can store the compiled expressions
and reuse them to perform repeated searches::

>>> import jmespathv041p
>>> path = jmespathv041p.compile('foo.bar')
>>> path.search({'foo': {'bar': 'baz'}})
'baz'
>>> path.search({'foo': {'bar': 'other'}})
'other'

You can also use the ``jmespathv041p.parser.Parser`` class directly
if you want more control.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

jmespathv041p-0.4.1.tar.gz (14.5 kB view hashes)

Uploaded Source

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page