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Prance provides parsers for Swagger/OpenAPI 2.0 and 3.0 <http://swagger.io/specification/>
__ API specifications in Python.
It uses openapi\_spec\_validator <https://github.com/p1c2u/openapi-spec-validator>
,
swagger\_spec\_validator <https://github.com/Yelp/swagger_spec_validator>
or
flex <https://github.com/pipermerriam/flex>
__
to validate specifications, but additionally resolves JSON references <https://tools.ietf.org/html/draft-pbryan-zyp-json-ref-03>
__
in accordance with the OpenAPI spec.
Mostly the latter involves handling non-URI references; OpenAPI is fine
with providing relative file paths, whereas JSON references require URIs
at this point in time.
Usage
Installation
Prance is available from PyPI, and can be installed via pip:
.. code:: bash
$ pip install prance
Note that this will install the code, but additional subpackages must be specified
to unlock various pieces of functionality. At minimum, a parsing backend must be
installed. For the CLI functionality, you need further dependencies.
The recommended installation installs the CLI, uses ICU and installs one validation
backend:
.. code:: bash
$ pip install prance[osv,icu,cli]
Make sure you have ICU Unicode Library <http://site.icu-project.org/home>
__ installed,
as well as Python dev library before running the commands above. If not, use the
following commands:
.. code:: bash
$ sudo apt-get install libicu-dev python3-dev # Ubuntu/Debian
$ sudo dnf install libicu-devel python3-devel # Fedora
Command Line Interface
After installing prance, a CLI is available for validating (and resolving
external references in) specs:
.. code:: bash
# Validates with resolving
$ prance validate path/to/swagger.yml
# Validates without resolving
$ prance validate --no-resolve path/to/swagger.yml
# Fetch URL, validate and resolve.
$ prance validate http://petstore.swagger.io/v2/swagger.json
Processing "http://petstore.swagger.io/v2/swagger.json"...
-> Resolving external references.
Validates OK as Swagger/OpenAPI 2.0!
Validation is not the only feature of prance. One of the side effects of
resolving is that from a spec with references, one can create a fully resolved
output spec. In the past, this was done via options to the validate
command,
but now there's a specific command just for this purpose:
.. code:: bash
# Compile spec
$ prance compile path/to/input.yml path/to/output.yml
Lastly, with the arrival of OpenAPI 3.0.0, it becomes useful for tooling to
convert older specs to the new standard. Instead of re-inventing the wheel,
prance just provides a CLI command for passing specs to the web API of
swagger2openapi <https://github.com/Mermade/swagger2openapi>
__ - a working
internet connection is therefore required for this command:
.. code:: bash
# Convert spec
$ prance convert path/to/swagger.yml path/to/openapi.yml
Code
Most likely you have spec file and want to parse it:
.. code:: python
from prance import ResolvingParser
parser = ResolvingParser('path/to/my/swagger.yaml')
parser.specification # contains fully resolved specs as a dict
Prance also includes a non-resolving parser that does not follow JSON
references, in case you prefer that.
.. code:: python
from prance import BaseParser
parser = BaseParser('path/to/my/swagger.yaml')
parser.specification # contains specs as a dict still containing JSON references
On Windows, the code reacts correctly if you pass posix-like paths
(/c:/swagger
) or if the path is relative. If you pass absolute
windows path (like c:\swagger.yaml
), you can use
prance.util.fs.abspath
to convert them.
URLs can also be parsed:
.. code:: python
parser = ResolvingParser('http://petstore.swagger.io/v2/swagger.json')
Largely, that's it. There is a whole slew of utility code that you may
or may not find useful, too. Look at the full documentation <https://prance.readthedocs.io/en/latest/#api-modules>
__ for details.
Compatibility
Python Versions
Version 0.16.2 is the last version supporting Python 2. It was released on
Nov 12th, 2019. Python 2 reaches end of life at the end of 2019. If you wish
for updates to the Python 2 supported packages, please contact the maintainer
directly.
Until fairly recently, we also tested with PyPy <https://www.pypy.org/>
.
Unfortunately, Travis isn't very good at supporting this. So in the absence
of spare time, they're disabled. Issue 50 <https://github.com/jfinkhaeuser/prance/issues/50>
tracks progress on that.
Similarly, but less critically, Python 3.4 is no longer receiving a lot of
love from CI vendors, so automated builds on that version are no longer
supported.
Backends
Different validation backends support different features.
+------------------------+----------------+-----------------+-------------+-------------------------------------------------------+----------------+-----------------------------------------------------------------------------------+
| Backend | Python Version | OpenAPI Version | Strict Mode | Notes | Available From | Link |
+========================+================+=================+=============+=======================================================+================+===================================================================================+
| swagger-spec-validator | 2 and 3 | 2.0 only | yes | Slow; does not accept integer keys (see strict mode). | prance 0.1 | swagger\_spec\_validator <https://github.com/Yelp/swagger_spec_validator>
__ |
+------------------------+----------------+-----------------+-------------+-------------------------------------------------------+----------------+-----------------------------------------------------------------------------------+
| flex | 2 and 3 | 2.0 only | n/a | Fastest; unfortunately deprecated. | prance 0.8 | flex <https://github.com/pipermerriam/flex>
__ |
+------------------------+----------------+-----------------+-------------+-------------------------------------------------------+----------------+-----------------------------------------------------------------------------------+
| openapi-spec-validator | 2 and 3 | 2.0 and 3.0 | yes | Slow; does not accept integer keys (see strict mode). | prance 0.11 | openapi\_spec\_validator <https://github.com/p1c2u/openapi-spec-validator>
__ |
+------------------------+----------------+-----------------+-------------+-------------------------------------------------------+----------------+-----------------------------------------------------------------------------------+
You can select the backend in the constructor of the parser(s):
.. code:: python
parser = ResolvingParser('http://petstore.swagger.io/v2/swagger.json', backend = 'openapi-spec-validator')
No backend is included in the dependencies; they are detected at run-time. If you install them,
they can be used:
.. code:: bash
$ pip install openapi-spec-validator
$ pip install prance
$ prance validate --backend=openapi-spec-validator path/to/spec.yml
A note on flex usage: While flex is the fastest validation backend, unfortunately it is no longer
maintained and there are issues with its dependencies. For one thing, it depends on a version of PyYAML
that contains security flaws. For another, it depends explicitly on older versions of click
.
If you use the flex subpackage, therefore, you do so at your own risk.
Compatibility
See COMPATIBILITY.rst <https://github.com/jfinkhaeuser/prance/blob/master/COMPATIBILITY.rst>
__
for a list of known issues.
Partial Reference Resolution
It's possible to instruct the parser to only resolve some kinds of references.
This allows e.g. resolving references from external URLs, whilst keeping local
references (i.e. to local files, or file internal) intact.
.. code:: python
from prance import ResolvingParser
from prance.util.resolver import RESOLVE_HTTP
parser = ResolvingParser('/path/to/spec', resolve_types = RESOLVE_HTTP)
Multiple types can be specified by OR-ing constants together:
.. code:: python
from prance import ResolvingParser
from prance.util.resolver import RESOLVE_HTTP, RESOLVE_FILES
parser = ResolvingParser('/path/to/spec', resolve_types = RESOLVE_HTTP | RESOLVE_FILES)
Extensions
Prance includes the ability to reference outside swagger definitions
in outside Python packages. Such a package must already be importable
(i.e. installed), and be accessible via the
ResourceManager API <https://setuptools.readthedocs.io/en/latest/pkg_resources.html#resourcemanager-api>
__
(some more info here <https://setuptools.readthedocs.io/en/latest/setuptools.html#including-data-files>
__).
For example, you might create a package common_swag
with the file
base.yaml
containing the definition
.. code:: yaml
definitions:
Severity:
type: string
enum:
- INFO
- WARN
- ERROR
- FATAL
In the setup.py
for common_swag
you would add lines such as
.. code:: python
packages=find_packages('src'),
package_dir={'': 'src'},
package_data={
'': '*.yaml'
}
Then, having installed common_swag
into some application, you could
now write
.. code:: yaml
definitions:
Message:
type: object
properties:
severity:
$ref: 'python://common_swag/base.yaml#/definitions/Severity'
code:
type: string
summary:
type: string
description:
type: string
required:
- severity
- summary
Contributing
See CONTRIBUTING.md <https://github.com/jfinkhaeuser/prance/blob/master/CONTRIBUTING.md>
__ for details.
Professional support is available through finkhaeuser consulting <https://finkhaeuser.de>
__.
License
Licensed under MIT. See the LICENSE.txt <https://github.com/RonnyPfannschmidt/prance/blob/master/LICENSE.txt>
__ file for details.
"Prancing unicorn" logo image Copyright (c) Jens Finkhaeuser.
Made by Moreven B <http://morevenb.com/>
. Use of the logo is permitted under
the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license <https://creativecommons.org/licenses/by-nc-sa/4.0/>
.
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