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-generatorThe 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
-c, --custom-visitors PATH - A custom visitor that adds variables to the template.
--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.
$ fastapi-codegen --input api.yaml --output appapi.yaml
openapi: "3.0.0"
info:
version: 1.0.0
title: Swagger Petstore
license:
name: MIT
servers:
- url: https://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
"""
passapp/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: strIf 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.yamlThese 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
importsall imports statementsinfoall info statementsoperationsoperationsis list ofoperationoperation.typeHTTP METHODoperation.pathPathoperation.snake_case_pathSnake-cased Pathoperation.responseresponse objectoperation.function_namefunction name is createdoperationIdorMETHOD+Pathoperation.snake_case_argumentsSnake-cased function argumentsoperation.securitySecurityoperation.summarya summary
main.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 %}
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_visitorhttps://pypi.org/project/fastapi-code-generator
fastapi-code-generator is released under the MIT License. https://www.opensource.org/licenses/mit-license