fastapi-code-generator
Advanced tools
This code generator creates a FastAPI app from an openapi file.
fastapi-code-generator uses datamodel-code-generator to generate pydantic models
See documentation for more details.
To install fastapi-code-generator:
$ pip install fastapi-code-generator
The fastapi-code-generator command:
Usage: fastapi-codegen [OPTIONS]
Options:
-i, --input FILENAME [required]
-o, --output PATH [required]
-t, --template-dir PATH
-m, --model-file Specify generated model file path + name, if not default to models.py
-r, --generate-routers Generate modular api with multiple routers using RouterAPI (for bigger applications).
--specify-tags Use along with --generate-routers to generate specific routers from given list of tags.
-c, --custom-visitors PATH - A custom visitor that adds variables to the template.
-d, --output-model-type Specify a Pydantic base model to use (see [datamodel-code-generator](https://github.com/koxudaxi/datamodel-code-generator); default is `pydantic.BaseModel`).
-p, --python-version Specify a Python version to target (default is `3.8`).
--install-completion Install completion for the current shell.
--show-completion Show completion for the current shell, to copy it
or customize the installation.
--help Show this message and exit.
Specify the Pydantic 2 BaseModel version in the command line, for example:
$ fastapi-codegen --input api.yaml --output app --output-model-type pydantic_v2.BaseModel
$ fastapi-codegen --input api.yaml --output app
openapi: "3.0.0"
info:
version: 1.0.0
title: Swagger Petstore
license:
name: MIT
servers:
- url: http://petstore.swagger.io/v1
paths:
/pets:
get:
summary: List all pets
operationId: listPets
tags:
- pets
parameters:
- name: limit
in: query
description: How many items to return at one time (max 100)
required: false
schema:
type: integer
format: int32
responses:
'200':
description: A paged array of pets
headers:
x-next:
description: A link to the next page of responses
schema:
type: string
content:
application/json:
schema:
$ref: "#/components/schemas/Pets"
default:
description: unexpected error
content:
application/json:
schema:
$ref: "#/components/schemas/Error"
x-amazon-apigateway-integration:
uri:
Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${PythonVersionFunction.Arn}/invocations
passthroughBehavior: when_no_templates
httpMethod: POST
type: aws_proxy
post:
summary: Create a pet
operationId: createPets
tags:
- pets
responses:
'201':
description: Null response
default:
description: unexpected error
content:
application/json:
schema:
$ref: "#/components/schemas/Error"
x-amazon-apigateway-integration:
uri:
Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${PythonVersionFunction.Arn}/invocations
passthroughBehavior: when_no_templates
httpMethod: POST
type: aws_proxy
/pets/{petId}:
get:
summary: Info for a specific pet
operationId: showPetById
tags:
- pets
parameters:
- name: petId
in: path
required: true
description: The id of the pet to retrieve
schema:
type: string
responses:
'200':
description: Expected response to a valid request
content:
application/json:
schema:
$ref: "#/components/schemas/Pets"
default:
description: unexpected error
content:
application/json:
schema:
$ref: "#/components/schemas/Error"
x-amazon-apigateway-integration:
uri:
Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${PythonVersionFunction.Arn}/invocations
passthroughBehavior: when_no_templates
httpMethod: POST
type: aws_proxy
components:
schemas:
Pet:
required:
- id
- name
properties:
id:
type: integer
format: int64
name:
type: string
tag:
type: string
Pets:
type: array
description: list of pet
items:
$ref: "#/components/schemas/Pet"
Error:
required:
- code
- message
properties:
code:
type: integer
format: int32
message:
type: string
app/main.py:
# generated by fastapi-codegen:
# filename: api.yaml
# timestamp: 2020-06-14T10:45:22+00:00
from __future__ import annotations
from typing import Optional
from fastapi import FastAPI, Query
from .models import Pets
app = FastAPI(version="1.0.0", title="Swagger Petstore", license="{'name': 'MIT'}",)
@app.get('/pets', response_model=Pets)
def list_pets(limit: Optional[int] = None) -> Pets:
"""
List all pets
"""
pass
@app.post('/pets', response_model=None)
def create_pets() -> None:
"""
Create a pet
"""
pass
@app.get('/pets/{pet_id}', response_model=Pets)
def show_pet_by_id(pet_id: str = Query(..., alias='petId')) -> Pets:
"""
Info for a specific pet
"""
pass
app/models.py:
# generated by datamodel-codegen:
# filename: api.yaml
# timestamp: 2020-06-14T10:45:22+00:00
from typing import List, Optional
from pydantic import BaseModel, Field
class Pet(BaseModel):
id: int
name: str
tag: Optional[str] = None
class Pets(BaseModel):
__root__: List[Pet] = Field(..., description='list of pet')
class Error(BaseModel):
code: int
message: str
If you want to generate custom *.py files then you can give a custom template directory to fastapi-code-generator with -t or --template-dir options of the command.
fastapi-code-generator will search for jinja2 template files in given template directory, for example some_jinja_templates/list_pets.py.
fastapi-code-generator --template-dir some_jinja_templates --output app --input api.yaml
These files will be rendered and written to the output directory. Also, the generated file names will be created with the template name and extension of *.py, for example app/list_pets.py will be a separate file generated from the jinja template alongside the default app/main.py
You can use the following variables in the jinja2 templates
imports all imports statementsinfo all info statementsoperations operations is list of operation
operation.type HTTP METHODoperation.path Pathoperation.snake_case_path Snake-cased Pathoperation.response response objectoperation.function_name function name is created operationId or METHOD + Pathoperation.snake_case_arguments Snake-cased function argumentsoperation.security Securityoperation.summary a summaryoperation.tags Tagsmain.jinja2
from __future__ import annotations
from fastapi import FastAPI
{{imports}}
app = FastAPI(
{% if info %}
{% for key,value in info.items() %}
{{ key }} = "{{ value }}",
{% endfor %}
{% endif %}
)
{% for operation in operations %}
@app.{{operation.type}}('{{operation.snake_case_path}}', response_model={{operation.response}})
def {{operation.function_name}}({{operation.snake_case_arguments}}) -> {{operation.response}}:
{%- if operation.summary %}
"""
{{ operation.summary }}
"""
{%- endif %}
pass
{% endfor %}
modular_template/main.jinja2:
from __future__ import annotations
from fastapi import FastAPI
from .routers import {{ routers | join(", ") }}
app = FastAPI(
{% if info %}
{% for key,value in info.items() %}
{% set info_value= value.__repr__() %}
{{ key }} = {{info_value}},
{% endfor %}
{% endif %}
)
{% for router in routers -%}
app.include_router({{router}}.router)
{% endfor -%}
@app.get("/")
async def root():
return {"message": "Gateway of the App"}
modular_template/routers.jinja2:
from __future__ import annotations
from fastapi import APIRouter
from fastapi import FastAPI
from ..dependencies import *
router = APIRouter(
tags=['{{tag}}']
)
{% for operation in operations %}
{% if operation.tags[0] == tag %}
@router.{{operation.type}}('{{operation.snake_case_path}}', response_model={{operation.response}}
{% if operation.additional_responses %}
, responses={
{% for status_code, models in operation.additional_responses.items() %}
'{{ status_code }}': {
{% for key, model in models.items() %}
'{{ key }}': {{ model }}{% if not loop.last %},{% endif %}
{% endfor %}
}{% if not loop.last %},{% endif %}
{% endfor %}
}
{% endif %}
{% if operation.tags%}
, tags={{operation.tags}}
{% endif %})
def {{operation.function_name}}({{operation.snake_case_arguments}}) -> {{operation.return_type}}:
{%- if operation.summary %}
"""
{{ operation.summary }}
"""
{%- endif %}
pass
{% endif %}
{% endfor %}
modular_template/dependencies.jinja2:
{{imports}}
Custom visitors allow you to pass custom variables to your custom templates.
E.g.
custom-template.jinja2
#{ % custom_header %}
from __future__ import annotations
from fastapi import FastAPI
...
custom-visitor.py
from typing import Dict, Optional
from fastapi_code_generator.parser import OpenAPIParser
from fastapi_code_generator.visitor import Visitor
def custom_visitor(parser: OpenAPIParser, model_path: Path) -> Dict[str, object]:
return {'custom_header': 'My header'}
visit: Visitor = custom_visitor
├── app # "app" is a Root directory
│ ├── main.py # "main" module
│ ├── models.py # "models" of the application
│ ├── dependencies.py # "dependencies" module, e.g. import app.dependencies
│ └── routers # "routers" is a "app subpackage"
│ ├── fat_cats.py # "fat_cats" submodule, e.g. import app.routers.fat_cats
│ ├── slim_dogs.py # "slim_dogs" submodule, e.g. import app.routers.slim_dogs
│ └── wild_boars.py # "wild_boars" submodule, e.g. import app.routers.wild_boars
See documentation of APIRouter OpenAPI for more details.
Generate main aside with all of its routers:
$ fastapi-codegen --input swagger.yaml --output app --generate-routers
Regenerate specific routers:
$ fastapi-codegen --input swagger.yaml --output app --generate-routers --specify-tags "Wild Boars, Fat Cats"
openapi: "3.0.0"
info:
version: 1.0.0
title: Swagger Petstore
license:
name: MIT
servers:
- url: /
- url: http://petstore.swagger.io/v1
- url: http://localhost:8080/
paths:
/boars:
get:
summary: List All Wild Boars
operationId: listWildBoars
tags:
- Wild Boars
parameters:
- name: limit
in: query
description: How many items to return at one time (max 100)
required: false
schema:
type: integer
responses:
'200':
description: An array of wild boars
content:
application/json:
schema:
$ref: "#/components/schemas/WildBoars"
post:
summary: Create a Wild Boar
operationId: createWildBoars
tags:
- Wild Boars
responses:
'201':
description: Null response
/boars/{boarId}:
get:
summary: Info For a Specific Boar
operationId: showBoarById
tags:
- Wild Boars
parameters:
- name: boarId
in: path
required: true
description: The id of the boar to retrieve
schema:
type: string
responses:
'200':
description: Expected response to a valid request
content:
application/json:
schema:
$ref: "#/components/schemas/Pet"
/cats:
get:
summary: List All Fat Cats
operationId: listFatCats
tags:
- Fat Cats
parameters:
- name: limit
in: query
description: How many items to return at one time (max 100)
required: false
schema:
type: integer
responses:
'200':
description: An array of fat cats
content:
application/json:
schema:
$ref: "#/components/schemas/FatCats"
post:
summary: Create a Fat Cat
operationId: createFatCats
tags:
- Fat Cats
responses:
'201':
description: Null response
/cats/{catId}:
get:
summary: Info For a Specific Cat
operationId: showCatById
tags:
- Fat Cats
parameters:
- name: catId
in: path
required: true
description: The id of the cat to retrieve
schema:
type: string
responses:
'200':
description: Expected response to a valid request
content:
application/json:
schema:
$ref: "#/components/schemas/Pet"
/dogs:
get:
summary: List All Slim Dogs
operationId: listSlimDogs
tags:
- Slim Dogs
parameters:
- name: limit
in: query
description: How many items to return at one time (max 100)
required: false
schema:
type: integer
responses:
'200':
description: An array of slim dogs
content:
application/json:
schema:
$ref: "#/components/schemas/SlimDogs"
post:
summary: Create a Slim Dog
operationId: createSlimDogs
tags:
- Slim Dogs
responses:
'201':
description: Null response
/dogs/{dogId}:
get:
summary: Info For a Specific Dog
operationId: showDogById
tags:
- Slim Dogs
parameters:
- name: dogId
in: path
required: true
description: The id of the dog to retrieve
schema:
type: string
responses:
'200':
description: Expected response to a valid request
content:
application/json:
schema:
$ref: "#/components/schemas/Pet"
components:
schemas:
Pet:
required:
- id
- name
properties:
id:
type: integer
name:
type: string
tag:
type: string
FatCats:
type: array
description: list of fat cats
items:
$ref: "#/components/schemas/Pet"
SlimDogs:
type: array
description: list of slim dogs
items:
$ref: "#/components/schemas/Pet"
WildBoars:
type: array
description: list of wild boars
items:
$ref: "#/components/schemas/Pet"
app/main.py:
# generated by fastapi-codegen:
# filename: swagger.yaml
# timestamp: 2023-04-04T12:06:16+00:00
from __future__ import annotations
from fastapi import FastAPI
from .routers import fat_cats, slim_dogs, wild_boars
app = FastAPI(
version='1.0.0',
title='Swagger Petstore',
license={'name': 'MIT'},
servers=[
{'url': '/'},
{'url': 'http://petstore.swagger.io/v1'},
{'url': 'http://localhost:8080/'},
],
)
app.include_router(fat_cats.router)
app.include_router(slim_dogs.router)
app.include_router(wild_boars.router)
@app.get("/")
async def root():
return {"message": "Gateway of the App"}
app/models.py:
# generated by fastapi-codegen:
# filename: swagger.yaml
# timestamp: 2023-04-04T12:06:16+00:00
from __future__ import annotations
from typing import List, Optional
from pydantic import BaseModel, Field
class Pet(BaseModel):
id: int
name: str
tag: Optional[str] = None
class FatCats(BaseModel):
__root__: List[Pet] = Field(..., description='list of fat cats')
class SlimDogs(BaseModel):
__root__: List[Pet] = Field(..., description='list of slim dogs')
class WildBoars(BaseModel):
__root__: List[Pet] = Field(..., description='list of wild boars')
app/routers/fat_cats.py:
# generated by fastapi-codegen:
# filename: swagger.yaml
# timestamp: 2023-04-04T12:06:16+00:00
from __future__ import annotations
from fastapi import APIRouter
from ..dependencies import *
router = APIRouter(tags=['Fat Cats'])
@router.get('/cats', response_model=FatCats, tags=['Fat Cats'])
def list_fat_cats(limit: Optional[int] = None) -> FatCats:
"""
List All Fat Cats
"""
pass
@router.post('/cats', response_model=None, tags=['Fat Cats'])
def create_fat_cats() -> None:
"""
Create a Fat Cat
"""
pass
@router.get('/cats/{cat_id}', response_model=Pet, tags=['Fat Cats'])
def show_cat_by_id(cat_id: str = Path(..., alias='catId')) -> Pet:
"""
Info For a Specific Cat
"""
pass
app/routers/slim_dogs.py:
# generated by fastapi-codegen:
# filename: swagger.yaml
# timestamp: 2023-04-04T12:06:16+00:00
from __future__ import annotations
from fastapi import APIRouter
from ..dependencies import *
router = APIRouter(tags=['Slim Dogs'])
@router.get('/dogs', response_model=SlimDogs, tags=['Slim Dogs'])
def list_slim_dogs(limit: Optional[int] = None) -> SlimDogs:
"""
List All Slim Dogs
"""
pass
@router.post('/dogs', response_model=None, tags=['Slim Dogs'])
def create_slim_dogs() -> None:
"""
Create a Slim Dog
"""
pass
@router.get('/dogs/{dog_id}', response_model=Pet, tags=['Slim Dogs'])
def show_dog_by_id(dog_id: str = Path(..., alias='dogId')) -> Pet:
"""
Info For a Specific Dog
"""
pass
app/routers/wild_boars.py:
# generated by fastapi-codegen:
# filename: swagger.yaml
# timestamp: 2023-04-04T12:06:16+00:00
from __future__ import annotations
from fastapi import APIRouter
from ..dependencies import *
router = APIRouter(tags=['Wild Boars'])
@router.get('/boars', response_model=WildBoars, tags=['Wild Boars'])
def list_wild_boars(limit: Optional[int] = None) -> WildBoars:
"""
List All Wild Boars
"""
pass
@router.post('/boars', response_model=None, tags=['Wild Boars'])
def create_wild_boars() -> None:
"""
Create a Wild Boar
"""
pass
@router.get('/boars/{boar_id}', response_model=Pet, tags=['Wild Boars'])
def show_boar_by_id(boar_id: str = Path(..., alias='boarId')) -> Pet:
"""
Info For a Specific Boar
"""
pass
app/dependencies.py:
# generated by fastapi-codegen:
# filename: swagger.yaml
# timestamp: 2023-04-04T12:06:16+00:00
from __future__ import annotations
from typing import Optional
from fastapi import Path
from .models import FatCats, Pet, SlimDogs, WildBoars
https://pypi.org/project/fastapi-code-generator
fastapi-code-generator is released under the MIT License. http://www.opensource.org/licenses/mit-license
FAQs
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We found that fastapi-code-generator demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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