Documentation of prance 0.22.11.4.1.dev3+g225635a¶
Swagger/OpenAPI 2.0 Parser for Python
Prance provides parsers for Swagger/OpenAPI 2.0 and 3.0 API specifications in Python. It uses openapi_spec_validator, swagger_spec_validator or flex to validate specifications, but additionally resolves JSON references 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:
$ 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:
$ pip install prance[osv,icu,cli]
Make sure you have ICU Unicode Library installed, as well as Python dev library before running the commands above. If not, use the following commands:
$ 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:
# 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:
# 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 - a working internet connection is therefore required for this command:
# Convert spec
$ prance convert path/to/swagger.yml path/to/openapi.yml
Code¶
Most likely you have spec file and want to parse it:
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.
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:
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 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. Unfortunately, Travis isn’t very good at supporting this. So in the absence of spare time, they’re disabled. Issue 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 |
|
flex |
2 and 3 |
2.0 only |
n/a |
Fastest; unfortunately deprecated. |
prance 0.8 |
|
openapi-spec-validator |
2 and 3 |
2.0 and 3.0 |
yes |
Slow; does not accept integer keys (see strict mode). |
prance 0.11 |
You can select the backend in the constructor of the parser(s):
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:
$ 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 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.
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:
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 (some more info here).
For example, you might create a package common_swag
with the file
base.yaml
containing the definition
definitions:
Severity:
type: string
enum:
- INFO
- WARN
- ERROR
- FATAL
In the setup.py
for common_swag
you would add lines such as
packages=find_packages('src'),
package_dir={'': 'src'},
package_data={
'': '*.yaml'
}
Then, having installed common_swag
into some application, you could
now write
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 for details.
Professional support is available through finkhaeuser consulting.
License¶
Licensed under MIT. See the LICENSE.txt file for details.
“Prancing unicorn” logo image Copyright (c) Jens Finkhaeuser. Made by Moreven B. Use of the logo is permitted under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license.
API/Modules¶
Prance implements parsers for Swagger/OpenAPI 2.0 and 3.0.0 API specs. |
|
Defines Mixins for parsers. |
|
Functionality for converting from Swagger/OpenAPI 2.0 to OpenAPI 3.0.0. |
|
This submodule contains file format related utility code for Prance. |
|
This submodule contains file system utilities for Prance. |
|
This submodule contains specialty iterators over specs. |
|
This submodule contains a JSON inlining reference resolver. |
|
This submodule contains code for fetching/parsing URLs. |
|
This submodule contains helpers for exception handling. |
|
This module contains code for accessing values in nested data structures. |
Changes¶
Prance 0.22.11.04.0¶
Features¶
consolidate and unify openapi-spec-validator api usage (#132)
drop dead pythons and upgrade builds for python 3.7 - 3.10 (#137)
migrate from distutils.version to packaging.version (#138)
Prance 0.21.8.0 (2021-08-06)¶
Features¶
Initial translating parser to inline other specs to new names. (#101)
replace pyyaml with ruamel.yaml for modern yaml support (#110)
Adopt black as code formatter. (#113)
Bugfixes¶
RefResolver will again accept and if instructed resolve references using the “python” URL scheme. (#104)
Prance 0.21.2 (2021-05-18)¶
Bugfixes¶
widen chardet pin to ease dependency hell for when others haven’t updated to >4 (#98)
v0.21.1 (2021-05-18)¶
quickfix for a missed rst issue in readme
v0.21.0 (2021-05-18)¶
Features¶
Implement initial part of maintainer switch (#93)
@RonnyPfannschmidt is the new maintainer, plans to move to jazzband
License is now MIT after coordination with Jens
begin to use pre-commit + pyupgrade
set up for setuptools_scm as bumpversion breaks with normalized configfiles
github actions
modernize setup.py/cfg
return to towncrier default templates
v0.20.2¶
#83: Properly propagate strict mode down to nested resolvers.
v0.20.1¶
Bugfix release:
#85: Update dependencies, in particular chardet
Miscellaneous: #86
v0.20.0¶
#77: Translate local references in external files by injecting them into the main specification.
#78: Fix issue in RESOLVE_INTERNAL handling
v0.19.0¶
#72: Fix behaviour when attempting to resolve nonexistent local references: raise ResolutionError instead of what the OS provides.
#69: Improve documentation with regards to JSON Schema and OpenAPI interoperability; some things are just not very well defined, and we make some strict assumptions in prance.
Miscellaneous: #71
v0.18.3¶
Bugfix release:
#67: fix syntax warning.
#69: when resolving references, if URL parsing fails, provide context on which URL was being parsed in error message.
v0.18.2¶
Bugfix release:
#65: fix error in resolving files only with ResolvingParser.
v0.18.1¶
Maintenance release, focusing on change requests from users.
#23: Add support for partial resolution, i.e. resolving only internal references, local files, HTTP URLs, or any combination thereof.
#36: Improve error handling by mentioning strict mode when openapi-spec-validator raises TypeError with very little context.
#46: Reduce reliance on network in tests. Tests that require a network connection can now be skipped via “-m ‘not requires_network’”. Other tests have mocked connections.
#55: RefResolver could set recursion limits, but the ResolvingParser did not pass related options on to the resolver. Fixed that. Also create & use reference cache in ResolvingParser.
#60: Improve output when resolving references, by indicating the type of problem (missing key, index out of bounds) in the object or sequence where the error occurred.
v0.17.0¶
#51: Try a lot more bytes when detecting file encoding. The new value is meant to be a multiple of sector/cluster size that’s still reasonable on most OSes and volumes.
#49: Remove Python 2.7 from supported/built versions. The CI vendors also don’t love 3.4 any longer. Instead, we’ve added 3.7 and 3.8 where available.
Miscellaneous: #53
v0.16.2¶
#47: Fix deprecation warning by always preferring collections.abc over collections.
v0.16.1¶
#44: Add changelog generation via towncrier