fails.py

import requests
import json
import pandas as pd 
from io import StringIO
import time

url = "https://api.beta.ons.gov.uk/v1/filters?submitted=true"
ages = range(0,90)
ages = [str(a) for a in ages]
years = [2015,2016,2017]
years = [str(y) for y in years]
post = {
    "dataset": {
        "id": "mid-year-pop-est",
        "edition": "time-series",
        "version": 4
    },
    "dimensions": [
        {
            "name": "sex",
            "options": [
                "1", "2"
            ]},
            {"name": "age",
            "options": ages},
            {"name": "time",
            "options": years}
        
    ]
}

post_data = json.dumps(post)
r1 = requests.post(url = url,  data = post_data)  #works

filter_meta = json.loads(r1.text)
csv_location = filter_meta["links"]["filter_output"]["href"]
output_url = filter_meta['links']['filter_output']['href']


time.sleep(1)

r = requests.get(output_url)
filter_output_meta = json.loads(r.text)
print(filter_output_meta)
csv_location = filter_output_meta['downloads']['csv']['href']



# r = requests.get(csv_location)
# df = pd.read_csv(StringIO(text))
# df

works.py

import requests
import json
import pandas as pd 
from io import StringIO
import time

url = "https://api.beta.ons.gov.uk/v1/filters?submitted=true"
ages = range(0,90)
ages = [str(a) for a in ages]
years = [2015,2016,2017]
years = [str(y) for y in years]
post = {
    "dataset": {
        "id": "mid-year-pop-est",
        "edition": "time-series",
        "version": 4
    },
    "dimensions": [
        {
            "name": "sex",
            "options": [
                "1", "2"
            ]},
            {"name": "age",
            "options": ages},
            {"name": "time",
            "options": years},
            {"name": "geography",
            "options": ["E06000002"]},
        
    ]
}

post_data = json.dumps(post)
r1 = requests.post(url = url,  data = post_data)  #works

filter_meta = json.loads(r1.text)
csv_location = filter_meta["links"]["filter_output"]["href"]
output_url = filter_meta['links']['filter_output']['href']


time.sleep(1)

r = requests.get(output_url)
filter_output_meta = json.loads(r.text)
print(filter_output_meta)
csv_location = filter_output_meta['downloads']['csv']['href']



# r = requests.get(csv_location)
# df = pd.read_csv(StringIO(text))
# df