Days 9-12 API Method: PUT Issue

[gloc-mike]

I am working through "Days 9-12 API Star" in the 100 Days of Web Python course and I am having issues with the PUT method.

I have cross checked my code against the GitHub version and my code looks logically the same but when I test the PUT method using Postman the 'update_car' function is not called/executed.

I have added print statements to the 'update_car' function to confirm this and indeed there is nothing printed in the console. Adding a print to the 'get_car' function however does print to the console.

My sequence of testing is the some as the video i.e. submit a GET request from Postman (for id 55); the submit the PUT request with updated parameters in the body of the request.

I have created a Git of the server output: https://gist.github.com/gloc-mike/03d1b7eda91b3a07ced3c6efa4ce4d34

In that you can see that the GET request was submitted and the print statement shows id 55; then when I submit the PUT request, the server responds with a 302 (redirect?), does not print my debug messages and then performs a GET request (system generated).

I'm on Mac; PyCharm (2019.3.1); virtual environments pipenv and pyenv; Pyton 3.7.4; apistar version is the recommended version. Also tried running it from the terminal (to remove PyCharm from the equation) but I get the same results.

There is a setting in Postman:

Automatically follow redirects
Prevent requests that return a 300-series response from being automatically redirected.

which I have tried turning off (default is on) but apart from that nothing else has been changed in Postman.

The PUT request from Postman:

PUT /55 HTTP/1.1
Host: 127.0.0.1:5000
User-Agent: PostmanRuntime/7.20.1
Accept: */*
Cache-Control: no-cache
Postman-Token: 914028c8-fc63-47f0-a99f-9132150dd2d3,80314209-e775-4466-8bbd-426400394684
Accept-Encoding: gzip, deflate
Referer: http://127.0.0.1:5000/55
Connection: keep-alive
cache-control: no-cache
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW

Content-Disposition: form-data; name="manufacturer"

Jeep
------WebKitFormBoundary7MA4YWxkTrZu0gW--,
Content-Disposition: form-data; name="manufacturer"

Jeep
------WebKitFormBoundary7MA4YWxkTrZu0gW--
Content-Disposition: form-data; name="model"

Mountain High II
------WebKitFormBoundary7MA4YWxkTrZu0gW--,
Content-Disposition: form-data; name="manufacturer"

Jeep
------WebKitFormBoundary7MA4YWxkTrZu0gW--
Content-Disposition: form-data; name="model"

Mountain High II
------WebKitFormBoundary7MA4YWxkTrZu0gW--
Content-Disposition: form-data; name="year"

2001
------WebKitFormBoundary7MA4YWxkTrZu0gW--

My pipfile:

[[source]]
name = "pypi"
url = "https://pypi.org/simple"
verify_ssl = true

[dev-packages]

[packages]
pytest = "*"
apistar = ">=0.5.41,<0.5.1000"

[requires]
python_version = "3.7"

My version of app.py sans the delete method:

import json
from typing import List

from apistar import App, Route, types, validato
![Screen Shot 2019-12-20 at 18 40 08](https://user-images.githubusercontent.com/2324626/71239822-a5454d80-235b-11ea-9c70-7abdec867949.png)
![Screen Shot 2019-12-20 at 18 40 53](https://user-images.githubusercontent.com/2324626/71239826-ad04f200-235b-11ea-8c12-dcbf6ecf2201.png)

rs
from apistar.http import JSONResponse


# helpers
def _load_cars_data():
    with open('cars.json') as f:
        cars = json.loads(f.read())
        # create a dictionary of the form {car_id: car}
        return {car['id']: car for car in cars}


# To load in the cars call the cars helper function
cars_db = _load_cars_data()

# Some constants
VALID_MANUFACTURERS = set([car['manufacturer'] for car in cars_db.values()])
CAR_NOT_FOUND = 'Car not found!'


# Definition - using APIStar's types.Type to get access to validation &
# serialisation
class Car(types.Type):
    # No auto-incrementer available so assign ID in POST - hence the need to
    # use 'allow_null=True' in this code
    id = validators.Integer(allow_null=True)
    manufacturer = validators.String(enum=list(VALID_MANUFACTURERS))
    model = validators.String(max_length=35)
    year = validators.Integer(minimum=1900, maximum=2050)
    # Make something OPTIONAL just add "default=''"
    vin = validators.String(max_length=50, default='')


# API methods
def list_cars() -> List[Car]:
    # cars_db.items() returns key, value tuple so to get the value from the
    # tuple one must use index [1]
    # Wrapping 'car[1]' with Car() serialises it :)  i.e. turn a dictionary
    # into a Car object
    return [Car(car[1]) for car in sorted(cars_db.items())]


def create_car(car: Car) -> JSONResponse:
    # Since no auto-increment available, manually determine the length of the
    # DB and increment by 1
    car_id = max(cars_db.keys())+1
    # Update the ID for the car we want to create with the new ID
    car.id = car_id
    # Store the new car in the DB
    cars_db[car_id] = car
    return JSONResponse(Car(car), status_code=201)


def get_car(car_id: int) -> JSONResponse:
    print(f"GET car: {car_id}")
    car = cars_db.get(car_id)
    # if a car exists, ".get(car_id)" returns the car otherwise returns None
    if not car:
        error = {'error': CAR_NOT_FOUND}
        return JSONResponse(error, status_code=404)
    return JSONResponse(Car(car), status_code=200)


def update_car(car_id: int, car: Car) -> JSONResponse:
    print(f"PUT car: {car}")
    # Check to see if the car exists so it can be updated
    if not cars_db.get(car_id):
        error = {'error', CAR_NOT_FOUND}
        return JSONResponse(error, status_code=404)
    # So it's ok, go ahead and update the car
    car.id = car_id
    cars_db[car_id] = car
    print(f"PUT cars_db[car_id]: {cars_db[car_id]}")
    return JSONResponse(Car(car), status_code=200)


def delete_car(car_id: int) -> JSONResponse:
    pass

routes = [
    Route('/', method='GET', handler=list_cars),
    Route('/', method='POST', handler=create_car),
    Route('/{car_id}/', method='GET', handler=get_car),
    Route('/{car_id}/', method='PUT', handler=update_car),
    Route('/{car_id}/', method='DELETE', handler=delete_car),
]

app = App(routes=routes)

if __name__ == '__main__':
    app.serve('127.0.0.1', 5000, debug=True)

Any help with how I can trace this issue would be greatly appreciated.

Thanks
Michael

[gloc-mike]

Additional screenshots from Postman:
GET Method:

PUT Method:

[gloc-mike]

Should have read the CLOSED issues -- PUT requests require a trailing slash, duh :|

[mikeckennedy]

Thanks, glad you found the fix @gloc-mike I should probably update the video to point that out for the rest of the students. :)

[bbelderbos]

Re-opening issue to update the README to prevent this confusion.

[bbelderbos]

updated README, thanks again @gloc-mike

[mikeckennedy]

Thank you @bbelderbos and @gloc-mike !