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Generate Python model classes (pydantic, attrs, dataclasses) based on JSON datasets with typing module support

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bogdandm/json2python-models

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json2python-models

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Example

json2python-models is a Python tool that can generate Python models classes (pydantic, (sqlmodel, dataclasses, attrs) from JSON datasets.

Features

  • Full typing module support
  • Types merging - if some field contains data of different types this will be represented as Union type
  • Fields and models names generation (unicode support included)
  • Similar models generalization
  • Handling recursive data structures (i.e. family tree)
  • Detecting string serializable types (i.e. datetime or just stringify numbers)
  • Detecting fields containing string constants (Literal['foo', 'bar'])
  • Generation models as list (flat models structure) or tree (nested models)
  • Specifying when dictionaries should be processed as dict type (by default every dict is considered as some model)
  • CLI API with a lot of options

Table of Contents

Examples

Part of Path of Exile public items API

from pydantic import BaseModel, Field
from typing import List, Optional
from typing_extensions import Literal
class Tab(BaseModel):
 id_: str = Field(..., alias="id")
 public: bool
 stash_type: Literal["CurrencyStash", "NormalStash", "PremiumStash"] = Field(..., alias="stashType")
 items: List['Item']
 account_name: Optional[str] = Field(None, alias="accountName")
 last_character_name: Optional[str] = Field(None, alias="lastCharacterName")
 stash: Optional[str] = None
 league: Optional[Literal["Hardcore", "Standard"]] = None

F1 Season Results

----- Show ----- 
driver_standings.json
[
 {
 "season": "2019",
 "round": "3",
 "DriverStandings": [
 {
 "position": "1",
 "positionText": "1",
 "points": "68",
 "wins": "2",
 "Driver": {
 "driverId": "hamilton",
 "permanentNumber": "44",
 "code": "HAM",
 "url": "http://en.wikipedia.org/wiki/Lewis_Hamilton",
 "givenName": "Lewis",
 "familyName": "Hamilton",
 "dateOfBirth": "1985-01-07",
 "nationality": "British"
 },
 "Constructors": [
 {
 "constructorId": "mercedes",
 "url": "http://en.wikipedia.org/wiki/Mercedes-Benz_in_Formula_One",
 "name": "Mercedes",
 "nationality": "German"
 }
 ]
 },
 ...
 ]
 }
]

json2models -f pydantic -m DriverStandings driver_standings.json

r"""
generated by json2python-models v0.2.0 at Mon May 4 17:46:30 2020
command: /opt/projects/json2python-models/venv/bin/json2models -f pydantic -s flat -m DriverStandings driver_standings.json
"""
from pydantic import BaseModel, Field
from typing import List
from typing_extensions import Literal
class DriverStandings(BaseModel):
 season: int
 round_: int = Field(..., alias="round")
 DriverStandings: List['DriverStanding']
class DriverStanding(BaseModel):
 position: int
 position_text: int = Field(..., alias="positionText")
 points: int
 wins: int
 driver: 'Driver' = Field(..., alias="Driver")
 constructors: List['Constructor'] = Field(..., alias="Constructors")
class Driver(BaseModel):
 driver_id: str = Field(..., alias="driverId")
 permanent_number: int = Field(..., alias="permanentNumber")
 code: str
 url: str
 given_name: str = Field(..., alias="givenName")
 family_name: str = Field(..., alias="familyName")
 date_of_birth: str = Field(..., alias="dateOfBirth")
 nationality: str
class Constructor(BaseModel):
 constructor_id: str = Field(..., alias="constructorId")
 url: str
 name: str
 nationality: Literal["Austrian", "German", "American", "British", "Italian", "French"]

Swagger

----- Show -----

swagger.json from any online API (I tested file generated by drf-yasg and another one for Spotify API)

It requires a bit of tweaking:

  • Some fields store routes/models specs as dicts
  • There are a lot of optional fields, so we reduce merging threshold
  • Disable string literals
json2models -f dataclasses -m Swagger testing_tools/swagger.json \
 --dict-keys-fields securityDefinitions paths responses definitions properties \
 --merge percent_50 number --max-strings-literals 0

r"""
generated by json2python-models v0.2.0 at Mon May 4 18:08:09 2020
command: /opt/projects/json2python-models/json_to_models/__main__.py -s flat -f dataclasses -m Swagger testing_tools/swagger.json --max-strings-literals 0 --dict-keys-fields securityDefinitions paths responses definitions properties --merge percent_50 number
"""
from dataclasses import dataclass, field
from json_to_models.dynamic_typing import FloatString
from typing import Any, Dict, List, Optional, Union
@dataclass
class Swagger:
 swagger: FloatString
 info: 'Info'
 host: str
 schemes: List[str]
 base_path: str
 consumes: List[str]
 produces: List[str]
 security_definitions: Dict[str, 'Parameter_SecurityDefinition']
 security: List['Security']
 paths: Dict[str, 'Path']
 definitions: Dict[str, 'Definition_Schema']
@dataclass
class Info:
 title: str
 description: str
 version: str
@dataclass
class Security:
 api_key: Optional[List[Any]] = field(default_factory=list)
 basic: Optional[List[Any]] = field(default_factory=list)
@dataclass
class Path:
 parameters: List['Parameter_SecurityDefinition']
 post: Optional['Delete_Get_Patch_Post_Put'] = None
 get: Optional['Delete_Get_Patch_Post_Put'] = None
 put: Optional['Delete_Get_Patch_Post_Put'] = None
 patch: Optional['Delete_Get_Patch_Post_Put'] = None
 delete: Optional['Delete_Get_Patch_Post_Put'] = None
@dataclass
class Property:
 type_: str
 format_: Optional[str] = None
 xnullable: Optional[bool] = None
 items: Optional['Item_Schema'] = None
@dataclass
class Property_2E:
 type_: str
 title: Optional[str] = None
 read_only: Optional[bool] = None
 max_length: Optional[int] = None
 min_length: Optional[int] = None
 items: Optional['Item'] = None
 enum: Optional[List[str]] = field(default_factory=list)
 maximum: Optional[int] = None
 minimum: Optional[int] = None
 format_: Optional[str] = None
@dataclass
class Item:
 title: Optional[str] = None
 type_: Optional[str] = None
 ref: Optional[str] = None
 max_length: Optional[int] = None
 min_length: Optional[int] = None
@dataclass
class Parameter_SecurityDefinition:
 name: Optional[str] = None
 in_: Optional[str] = None
 required: Optional[bool] = None
 schema: Optional['Item_Schema'] = None
 description: Optional[str] = None
 type_: Optional[str] = None
@dataclass
class Delete_Get_Patch_Post_Put:
 operation_id: str
 description: str
 parameters: List['Parameter_SecurityDefinition']
 responses: Dict[str, 'Response']
 tags: List[str]
@dataclass
class Item_Schema:
 ref: str
@dataclass
class Response:
 description: str
 schema: Optional[Union['Item_Schema', 'Definition_Schema']] = None
@dataclass
class Definition_Schema:
 type_: str
 required: Optional[List[str]] = field(default_factory=list)
 properties: Optional[Dict[str, Union['Property', 'Property_2E']]] = field(default_factory=dict)
 ref: Optional[str] = None

Github-actions config files

----- Show -----

Github-actions model based on files from starter-workflows 

json2models -m Actions "./starter-workflows/ci/*.yml" -s flat -f pydantic -i yaml --dkf env with jobs

r"""
generated by json2python-models v0.2.3 at Tue Jul 13 19:52:43 2021
command: /opt/projects/json2python-models/venv/bin/json2models -m Actions ./starter-workflows/ci/*.yml -s flat -f pydantic -i yaml --dkf env with jobs
"""
from pydantic import BaseModel, Field
from typing import Dict, List, Optional, Union
from typing_extensions import Literal
class Actions(BaseModel):
 on: Union['On', List[Literal["push"]]]
 jobs: Dict[str, 'Job']
 name: Optional[str] = None
 env: Optional[Dict[str, Union[int, str]]] = {}
class On(BaseModel):
 push: Optional['Push'] = None
 pull_request: Optional['PullRequest'] = None
 release: Optional['Release'] = None
 schedule: Optional[List['Schedule']] = []
 workflow_dispatch: Optional[None] = None
class Push(BaseModel):
 branches: List[Literal["$default-branch"]]
 tags: Optional[List[Literal["v*.*.*"]]] = []
class PullRequest(BaseModel):
 branches: List[Literal["$default-branch"]]
class Release(BaseModel):
 types: List[Literal["created", "published"]]
class Schedule(BaseModel):
 cron: Literal["$cron-daily"]
class Job(BaseModel):
 runson: Literal["${{ matrix.os }}", "macOS-latest", "macos-latest", "ubuntu-18.04", "ubuntu-latest", "windows-latest"] = Field(..., alias="runs-on")
 steps: List['Step']
 name: Optional[str] = None
 environment: Optional[Literal["production"]] = None
 outputs: Optional['Output'] = None
 container: Optional['Container'] = None
 needs: Optional[Literal["build"]] = None
 permissions: Optional['Permission'] = None
 strategy: Optional['Strategy'] = None
 defaults: Optional['Default'] = None
 env: Optional[Dict[str, str]] = {}
class Step(BaseModel):
 uses: Optional[str] = None
 name: Optional[str] = None
 with_: Optional[Dict[str, Union[bool, float, str]]] = Field({}, alias="with")
 run: Optional[str] = None
 env: Optional[Dict[str, str]] = {}
 workingdirectory: Optional[str] = Field(None, alias="working-directory")
 id_: Optional[Literal["build-image", "composer-cache", "deploy-and-expose", "image-build", "login-ecr", "meta", "push-to-registry", "task-def"]] = Field(None, alias="id")
 if_: Optional[str] = Field(None, alias="if")
 shell: Optional[Literal["Rscript {0}"]] = None
class Output(BaseModel):
 route: str = Field(..., alias="ROUTE")
 selector: str = Field(..., alias="SELECTOR")
class Container(BaseModel):
 image: Literal["crystallang/crystal", "erlang:22.0.7"]
class Permission(BaseModel):
 contents: Literal["read"]
 packages: Literal["write"]
class Strategy(BaseModel):
 matrix: Optional['Matrix'] = None
 maxparallel: Optional[int] = Field(None, alias="max-parallel")
 failfast: Optional[bool] = Field(None, alias="fail-fast")
class Matrix(BaseModel):
 rversion: Optional[List[float]] = Field([], alias="r-version")
 pythonversion: Optional[List[float]] = Field([], alias="python-version")
 deno: Optional[List[Literal["canary", "v1.x"]]] = []
 os: Optional[List[Literal["macOS-latest", "ubuntu-latest", "windows-latest"]]] = []
 rubyversion: Optional[List[float]] = Field([], alias="ruby-version")
 nodeversion: Optional[List[Literal["12.x", "14.x", "16.x"]]] = Field([], alias="node-version")
 configuration: Optional[List[Literal["Debug", "Release"]]] = []
class Default(BaseModel):
 run: 'Run'
class Run(BaseModel):
 shell: Literal["bash"]

Example with preamble

----- Show -----

A simple example to demonstrate adding extra code before the class list. 

json2models -f pydantic --preamble "# set up defaults
USERNAME = 'user'
SERVER_IP = '127.0.0.1'
" -m Swagger testing_tools/swagger.json
r"""
generated by json2python-models v0.2.5 at Tue Aug 23 08:55:09 2022
command: json2models -f pydantic --preamble # set up defaults
USERNAME = 'user'
SERVER_IP = '127.0.0.1'
 -m Swagger testing_tools/swagger.json -o output.py
"""
from pydantic import BaseModel, Field
from typing import Any, List, Literal, Optional, Union
# set up defaults
USERNAME = 'user'
SERVER_IP = '127.0.0.1'
class Swagger(BaseModel):
 # etc.

Installation

To install it, use pip:

pip install json2python-models

Or you can build it from source:

git clone https://github.com/bogdandm/json2python-models.git
cd json2python-models
python setup.py install

Usage

CLI

For regular usage CLI tool is the best option. After you install this package you can use it as json2models <arguments> or python -m json_to_models <arguments>. I.e.:

json2models -m Car car_*.json -f attrs > car.py

Arguments:

  • -h, --help - Show help message and exit

  • -m, --model - Model name and its JSON data as path or unix-like path pattern. *, ** or ? patterns symbols are supported. JSON data could be an array of models or single model. If this file contains dict with nested list than you can pass <JSON lookup>. Deep lookups are supported by dot-separated path. If no lookup needed pass '-' as <JSON lookup> (default)

    • Format: -m <Model name> [<JSON lookup>] <File path or pattern>
    • Example: -m Car audi.json -m Car results reno.json

  • -i, --input-format - Input file format (parser). Default is JSON parser. Yaml parser requires PyYaml or ruamel.yaml to be installed. Ini parser uses builtin configparser. To implement new one - add new method to cli.FileLoaders (and create pull request :) )

    • Format: -i {json, yaml, ini}
    • Example: -i yaml
    • Default: -i json

  • -o, --output - Output file

    • Format: -o <FILE>
    • Example: -o car_model.py

  • -f, --framework - Model framework for which python code is generated. base (default) mean no framework so code will be generated without any decorators and additional meta-data.

    • Format: -f {base, pydantic, sqlmodel, attrs, dataclasses, custom}
    • Example: -f pydantic
    • Default: -f base
    • Warning: SQLModel generator does not support Relationships and Foreign keys, they have to be added manually

  • -s, --structure - Models composition style.

    • Format: -s {flat, nested}
    • Example: -s nested
    • Default: -s flat

  • --preamble - Additional material to be

    • Format: --preamble "<formatted python code string to be added after module imports>"
    • Example:
    --preamble "# set up defaults
USERNAME = 'user'
SERVER = '127.0.0.1'"
    • Optional

  • --datetime - Enable datetime/date/time strings parsing.

    • Default: disabled
    • Warning: This can lead to 6-7 times slowdown on large datasets. Be sure that you really need this option.

  • --disable-unicode-conversion, --no-unidecode - Disable unicode conversion in field labels and class names

    • Default: enabled

  • --strings-converters - Enable generation of string types converters (i.e. IsoDatetimeString or BooleanString).

    • Default: disabled

  • --max-strings-literals - Generate Literal['foo', 'bar'] when field have less than NUMBER string constants as values.

    • Format: --max-strings-literals <NUMBER>
    • Default: 10 (generator classes could override it)
    • Example: --max-strings-literals 5 - only 5 literals will be saved and used to code generation
    • Note: There could not be more than 15 literals per field (for performance reasons)
    • Note: attrs code generator do not use Literals and just generate str fields instead

  • --merge - Merge policy settings. Possible values are:

    • Format: --merge MERGE_POLICY [MERGE_POLICY ...]
    • Possible values (MERGE_POLICY):
      • percent[_<percent>] - two models had a certain percentage of matched field names. Custom value could be i.e. percent_95.
      • number[_<number>] - two models had a certain number of matched field names.
      • exact - two models should have exact same field names to merge.
    • Example: --merge percent_95 number_20 - merge if 95% of fields are matched or 20 of fields are matched
    • Default: --merge percent_70 number_10

  • --dict-keys-regex, --dkr - List of regular expressions (Python syntax). If all keys of some dict are match one of the pattern then this dict will be marked as dict field but not nested model.

    • Format: --dkr RegEx [RegEx ...]
    • Example: --dkr node_\d+ \d+_\d+_\d+
    • Note: ^ and $ (string borders) tokens will be added automatically, but you have to escape other special characters manually.
    • Optional

  • --dict-keys-fields, --dkf - List of model fields names that will be marked as dict fields

    • Format: --dkf FIELD_NAME [FIELD_NAME ...]
    • Example: --dkf "dict_data" "mapping"
    • Optional

  • --code-generator - Absolute import path to GenericModelCodeGenerator subclass.

    • Format: --code-generator CODE_GENERATOR
    • Example: -f mypackage.mymodule.DjangoModelsGenerator
    • Note: Is ignored without -f custom but is required with it.

  • --code-generator-kwargs - List of GenericModelCodeGenerator subclass arguments (for __init__ method, see docs of specific subclass). Each argument should be in following format: argument_name=value or "argument_name=value with space". Boolean values should be passed in JS style: true or false

    • Format: --code-generator-kwargs [NAME=VALUE [NAME=VALUE ...]]
    • Example: --code-generator-kwargs kwarg1=true kwarg2=10 "kwarg3=It is string with spaces"
    • Optional

  • --disable-str-serializable-types - List of python types for which StringSerializable should be disabled. Alternatively you could use the name of StringSerializable subclass itself (i.e. IntString).

    • Format: --disable-str-serializable-types [TYPE [TYPE ...]]
    • Example: --disable-str-serializable-types float int BooleanString IsoDatetimeString
    • Optional

Low level API

-

Tests

To run tests you should clone project and run setup.py script:

git clone https://github.com/bogdandm/json2python-models.git
cd json2python-models
python setup.py test -a '<pytest additional arguments>'

Also, I would recommend you to install pytest-sugar for pretty printing test results

Test examples

You can find out some examples of usage of this project at testing_tools/real_apis/...

Each file contains functions to download data from some online API (references included at the top of file) and main function that generates and prints code. Some examples may print debug data before actual code. Downloaded data will be saved at testing_tools/real_apis/<name of example>/<dataset>.json

Built With

Test tools:

Contributing

Feel free to open pull requests with new features or bug fixes. Just follow few rules:

  1. Always use some code formatter (black or PyCharm built-in)
  2. Keep code coverage above 95-98%
  3. All existing tests should be passed (including test examples from testing_tools/real_apis)
  4. Use typing module
  5. Fix codacy issues from your PR

License

This project is licensed under the MIT License - see the LICENSE file for details

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Generate Python model classes (pydantic, attrs, dataclasses) based on JSON datasets with typing module support

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