Endpoint Routing to Your Python Views

Connexion uses the operationId from each Operation Object to identify which Python function should handle each URL.

Explicit Routing:

      operationId: myapp.api.hello_world

If you provided this path in your specification POST requests to http://MYHOST/hello_world, it would be handled by the function hello_world in myapp.api module. Optionally, you can include x-swagger-router-controller in your operation definition, making operationId relative:

      x-swagger-router-controller: myapp.api
      operationId: hello_world

Keep in mind that Connexion follows how HTTP methods work in Flask and therefore HEAD requests will be handled by the operationId specified under GET in the specification. If both methods are supported, connexion.request.method can be used to determine which request was made.

Automatic Routing

To customize this behavior, Connexion can use alternative Resolvers—for example, RestyResolver. The RestyResolver will compose an operationId based on the path and HTTP method of the endpoints in your specification:

from connexion.resolver import RestyResolver

app = connexion.FlaskApp(__name__)
app.add_api('swagger.yaml', resolver=RestyResolver('api'))
       # Implied operationId: api.get
       # Implied operationId:
       # Implied operationId:

       # Implied operationId:
       # Implied operationId:
       # Implied operationId:
       # Implied operationId:

RestyResolver will give precedence to any operationId encountered in the specification. It will also respect x-swagger-router-controller. You may import and extend connexion.resolver.Resolver to implement your own operationId (and function) resolution algorithm.

Parameter Name Sanitation

The names of query and form parameters, as well as the name of the body parameter are sanitized by removing characters that are not allowed in Python symbols. I.e. all characters that are not letters, digits or the underscore are removed, and finally characters are removed from the front until a letter or an under-score is encountered. As an example:

>>> re.sub('^[^a-zA-Z_]+', '', re.sub('[^0-9a-zA-Z_]', '', '$top'))

Without this sanitation it would e.g. be impossible to implement an OData API.

Parameter Variable Converters

Connexion supports Flask’s int, float, and path route parameter variable converters. Specify a route parameter’s type as integer or number or its type as string and its format as path to use these converters. For example:

    # ...
      - name: name
        in: path
        required: true
        type: string
        format: path

will create an equivalent Flask route /greeting/<path:name>, allowing requests to include forward slashes in the name url variable.

API Versioning and basePath

Setting a base path is useful for versioned APIs. An example of a base path would be the 1.0 in http://MYHOST/1.0/hello_world.

If you are using OpenAPI 3.x.x, you set your base URL path in the servers block of the specification. You can either specify a full URL, or just a relative path.

  - url: https://MYHOST/1.0
    description: full url example
  - url: /1.0
    description: relative path example


If you are using OpenAPI 2.0, you can define a basePath on the top level of your OpenAPI 2.0 specification.

basePath: /1.0


If you don’t want to include the base path in your specification, you can provide it when adding the API to your application:

app.add_api('my_api.yaml', base_path='/1.0')

Swagger JSON

Connexion makes the OpenAPI/Swagger specification in JSON format available from swagger.json in the base path of the API.

You can disable the Swagger JSON at the application level:

app = connexion.FlaskApp(__name__, specification_dir='swagger/',

You can also disable it at the API level:

app = connexion.FlaskApp(__name__, specification_dir='swagger/')
app.add_api('my_api.yaml', swagger_json=False)