What's the syntax for web REST fastAPI GET function, and the request.get function where one of the input variable is List, or Numpy Array

Question

been driving me crazy with the syntax for the past week, so hopefully an enlightened one can point me out! I’ve traced these posts, but somehow I couldn’t get them to work

I am looking to have an input variable where it is a list, and a numpy array; for feeding into a fastAPI get function, and then calling it via a request.get. Somehow, I cannot get the arguments/syntax correct.

FastAPI POST request with List input raises 422 Unprocessable Entity error

Can FastAPI/Pydantic individually validate input items in a list?

I have the following web API defined :

import typing
from typing import List
from fastapi import Query
from fastapi import FastAPI

 @appOne.get("/sabr/funcThree")
        def funcThree(x1: List[float], x2: np.ndarray):
            return {"x1" : x1, "x2" : x2}

Then, I try to call the function from a jupyter notebook:

import requests
url_ = "http://127.0.0.1:8000/sabr/"
func_ = "funcThree"

items = [1, 2, 3, 4, 5]

params = {"x1" : items, "x2" : np.array([3,100])}
print(url_ + func_)
requests.get(url_ + func_, params = params).json()

I get the following error below…

{'detail': [{'loc': ['body', 'x1'],
   'msg': 'field required',
   'type': 'value_error.missing'}]}

It’s driving me CRAZY …. Help!!!!

though answered in the above, as it is a related question….. I put a little update.

I add in a ‘type_’ field, so that it can return different type of results. But somehow, the json= params is NOT picking it up. Below is the python fastAPI code :

@app.get("/sabr/calib_test2")
    def calib_test2(x1: List[float] = [1, 2, 3], x2: List[float] = [4, 5, 6]
,  type_: int = 1):
        s1 = np.array(x1)
        s2 = np.array(x2)
        # corr = np.corrcoef(x1, x2)[0][1]
        if type_ == 1:
            return {"x1": x1, "x1_sum": s1.sum(), "x2": x2, 
"x2_sum": s2.sum(), "size_x1": s1.shape}
        elif type_ == 2:
            return ['test', x1, s1.sum(), x2, s2.sum(), s1.shape]
        else:
            return [0, 0, 0]

But, it seems somehow the type_ input I am keying in, is NOT being fed-through… Help…

url_ = "http://127.0.0.1:8000/sabr/"
func_ = "calib_test2"
item1 = [1, 2, 3, 4, 5]
item2 = [4, 5, 6, 7, 8]

all_ = url_ + func_
params = {"x1": item1, "x2": item2, "type_": '2', "type_": 2}
resp = requests.get(all_, json = params)
# resp.raise_for_status()
resp.json()

Results keep being :

{'x1': [1.0, 2.0, 3.0, 4.0, 5.0],
 'x1_sum': 15.0,
 'x2': [4.0, 5.0, 6.0, 7.0, 8.0],
 'x2_sum': 30.0,
 'size_x1': [5]}

Asked By: Kiann

||

Source

Answer 1

You can’t use a Numpy array directly as a data format. If you’re looking to ingest a 2D numpy array, you’ll

need to use POST (there’s no good way to represent a 2D array as a query paremeter)
need to cast a list-of-lists back to a numpy array

so the server side ends up looking like

from typing import List

import numpy as np
from fastapi import FastAPI

app = FastAPI()


@app.post("/sabr")
def sabr(x1: List[float], x2: List[List[float]]):
    s = np.array(x2)
    return {"x1": x1, "x2": s.sum(), "size": s.shape}

and on the client side, you’ll need to tolist the numpy array and POST it as JSON:

import numpy as np
import requests

url = "http://127.0.0.1:8000/sabr"
items = [1, 2, 3, 4, 5]
params = {
    "x1": items,
    "x2": np.random.randint(0, 100, size=[3, 100]).tolist(),
}
resp = requests.post(url, json=params)
resp.raise_for_status()
print(resp.json())

This outputs (e.g., since it’s random)

{'x1': [1.0, 2.0, 3.0, 4.0, 5.0], 'x2': 15320.0, 'size': [3, 100]}

Answered By: AKX

What's the syntax for web REST fastAPI GET function, and the request.get function where one of the input variable is List, or Numpy Array

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