Python API 使用嵌套 for 循环调用 cursor 分页，无法从循环内部检索字典键

Question

I am struggling to figure out how to implement cursor pagination from the API I am trying to query. I previously tried to declare the first cursor, and then run a while cursor is not None loop, but that gave me more errors than the for loop lol.

I divided by 100 for the number of pages, as the api documentation dictates the max limit from a singular api call is 100.

 import requests import json import pandas as pd url = "https://deep-index.moralis.io/api/v2/0xa081AE42802E0Be86f5A6dD9274ADf50C9986a1D/nft?chain=eth&format=decimal" headers = { "Accept": "application/json", "X-API-Key": "myapikey" } medRare = [] def get_total(): r1 = requests.get(url, headers = headers) r2 = json.loads(r1.text) global pages pages = round(r2['total']/100) get_total() for x in range(2): r1 = requests.get(url, headers = headers) r2 = json.loads(r1.text) r3 = r2['result'] for nfts in r3: medRare.append(nfts) cursor = r2['cursor'] url = url+"&cursor="+str(cursor)

The error I am getting is on the "r3 = r2['result']" line inside of the loop, KeyError: 'result'

I am able to recreate this loop manually with no issues, but when I try to make it automatic with recursion it is giving me these errors. Any help is appreciated, TIA.

r2 results

Answer 1

The problem may be caused by url = url+"&cursor="+str(cursor) . This will overwrite the existing url instead of modifying the cursor string. Let say the for loop iterates 3 times. The value of url will become

# first iteration
example.com&cursor=cursor1
# second iteration
example.com&cursor=cursor1&cursor=cursor2
# third iteration
example.com&cursor=cursor1&cursor=cursor2&cursor=cursor3

Thus, the second API call onwards will return unexpected result, eg r2['result'] may be equal to None . You can try to use another variable name to prevent this from happening.

url = "example.com"
headers = {"Accept": "application/json","X-API-Key": "my-api-key"}
results = []

def get_total():
    r1 = requests.get(url, headers = headers)
    r2 = json.loads(r1.text)
    return round(r2['total']/100)

pages = get_total()

for x in range(1,pages):
    r1 = requests.get(url, headers = headers)
    r2 = json.loads(r1.text)
    r3 = r2['result']
    
    for i in r3:
        results.append(i)
        
    cursor = r2['cursor']

    full_url = url+"&cursor="+str(cursor)