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https://github.com/jsonschema-typed/jsonschema-typed
Use JSON Schema for type checking in Python
https://github.com/jsonschema-typed/jsonschema-typed
experimental json json-schema mypy static-analysis typing
Last synced: 2 months ago
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Use JSON Schema for type checking in Python
- Host: GitHub
- URL: https://github.com/jsonschema-typed/jsonschema-typed
- Owner: jsonschema-typed
- License: mit
- Created: 2019-04-25T18:40:33.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2024-03-13T06:30:41.000Z (10 months ago)
- Last Synced: 2024-11-18T18:12:15.434Z (2 months ago)
- Topics: experimental, json, json-schema, mypy, static-analysis, typing
- Language: Python
- Size: 136 KB
- Stars: 39
- Watchers: 4
- Forks: 7
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
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README
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[](https://pypi.org/project/jsonschema-typed/)
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# JSON Schema-powered type annotations
This package provides a way to automatically produce type annotations based
on [`jsonschema`-schemas](https://json-schema.org).
Not all concepts covered by `jsonschema` are expressible within Python typing annotations. However, most things
will work like you'd expect. Most types are translated trivially
(`integer`, `number`, `string`, `array`, `boolean` and `null`).
The interesting type is `object`, which is translated into a [``TypedDict``](https://www.python.org/dev/peps/pep-0589/).
**Warning:** This is based on the [mypy plugin system](https://mypy.readthedocs.io/en/latest/extending_mypy.html), which
is stated to have no backwards compatibility guarantee. New versions of mypy might not be supported immediately.
## Example
A JSON schema:
```json
{
"$schema": "http://json-schema.org/draft-07/schema#",
"$id": "http://foo.qwerty/some/schema#",
"title": "Foo Schema",
"type": "object",
"properties": {
"title": {
"type": "string"
},
"awesome": {
"type": "number"
}
},
"required": ["title"]
}
```
A TypedDict:
```python
from typing import TYPE_CHECKING
from jsonschema_typed import JSONSchema
data: JSONSchema["path/to/schema.json"] = {"title": "baz"}
if TYPE_CHECKING:
reveal_type(data) # Revealed type is 'TypedDict('FooSchema', {'title': builtins.str,
# 'awesome'?: Union[builtins.int, builtins.float]})'
data["description"] = "there is no description" # TypedDict "FooSchema" has no key 'description'
data["awesome"] = 42
data["awesome"] = None # Argument 2 has incompatible type "None"; expected "Union[int, float]"
```
You can also get types of parts of a schema, as well as types of elements in arrays. Take a look at the
[test cases](tests/cases) for more examples of usage.
## Installation
```bash
pip install jsonschema-typed
```
You also need to enable the plugin(s) in your `mypy.ini` configuration file:
```toml
# mypy.ini
[mypy]
plugins = jsonschema_typed.plugin, jsonschema_typed.optional_typed_dict
# Due to a quirk of how these type hints are generated, mypy's caching breaks.
# Disabling caching might be required.
cache_dir = /dev/null
```
## Requirements
The above installations resolves the dependencies, which consist of `mypy` and `jsonschema` (naturally).
Testing has been done with versions:
- mypy==0.761
- jsonschema==3.2.0
Probably some older versions will also work. Report an [issue](https://github.com/jsonschema-typed/jsonschema-typed/issues)
if you need other versions.
## Limitations
- `additionalProperties` doesn't really have an equivalent in TypedDict.
- The ``default`` keyword is not supported; but see: https://github.com/python/mypy/issues/6131.
- Self-references (e.g. ``"#"``) can't really work properly until nested
forward-references are supported; see: https://github.com/python/mypy/issues/731.