I think I am missunderstanding how the async await is working, especially with a function from another file. So I want to get an adress from longitude and latitude using an axios call on an API

import { getAddressFromLongLat } from "../hooks/queries-hook";
import React, { useEffect, useState } from "react";

const Component = (props) => {
  const [address, setAddress] = useState(null);
  useEffect(() => {
    const fetchFromLongLat = async () => {
      if (props.coords) {
        const response = await getAddressFromLongLat(props.coords);
        console.log("response from nominatim "   JSON.stringify(response, null, 4));
        setAddress(response);
      }
    };
    fetchFromLongLat();
  }, []);

  return <></>;
};

then into queries-hook.js

import axios from "axios";

export const getAddressFromLongLat = async (coords) => {
  const URL = "http://nominatim.openstreetmap.org/reverse";
  const response = await axios.get(URL, {
    params: {
      format: "json",
      lat: coords.lat,
      lon: coords.long
    },
    headers: {
      "Content-Type": "application/json; charset=UTF-8"
    }
  });
  return {
    street: response.address.road   " "   response.address.house_number,
    cp: response.address.postcode,
    city: response.address.town,
    country: response.address.country_code.toUpperCase()
  };
};

can someone explain me how I should write correctly the code with those async await to not have the error:

Possible Unhandled Promise Rejection (id: 0): TypeError: undefined is not an object (evaluating 'response.address.road')

CodePudding user response：

Issue is due to response does not contains address property and all the rest. But response.data do.

You had to add a console.log(response); before return to figure that out. The output for { "lat": 50.806002951249546, "long": 4.410705976188183 } will be this:

{
  "data": {
    "place_id": 113461740,
    "licence": "Data © OpenStreetMap contributors, ODbL 1.0. https://osm.org/copyright",
    "osm_type": "way",
    "osm_id": 30994925,
    "lat": "50.8066154",
    "lon": "4.410838323013642",
    "display_name": "Parc sportif des Trois Tilleuls, Avenue Léopold Wiener - Léopold Wienerlaan, Le Triangle - De Driehoek, Ватермаль-Буафор, Брюссельский столичный регион, 1170, Бельгия",
    "address": {
      "leisure": "Parc sportif des Trois Tilleuls",
      "road": "Avenue Léopold Wiener - Léopold Wienerlaan",
      "neighbourhood": "Le Triangle - De Driehoek",
      "town": "Ватермаль-Буафор",
      "county": "Брюссельский столичный регион",
      "region": "Брюссельский столичный регион",
      "ISO3166-2-lvl4": "BE-BRU",
      "postcode": "1170",
      "country": "Бельгия",
      "country_code": "be"
    },
    "boundingbox": [
      "50.8042107",
      "50.80902",
      "4.4079878",
      "4.4130556"
    ]
  },
  "status": 200,
  "statusText": "",
  ...
  (cutted)
} 

So fixed function:

const getAddressFromLongLat = async (coords) => {
  // switched to HTTPS here also
  const URL = "https://nominatim.openstreetmap.org/reverse";
  const response = await axios.get(URL, {
    params: {
      format: "json",
      lat: coords.lat,
      lon: coords.long
    },
    headers: {
      "Content-Type": "application/json; charset=UTF-8"
    }
  });
  const { data } = response; // equal to const data = response.data
  return {
    street: data.address.road   " "   data.address.house_number,
    cp: data.address.postcode,
    city: data.address.town,
    country: data.address.country_code.toUpperCase()
  };
};

CodePudding user response：

import axios from 'axios';
import React from 'react'
import { useEffect } from 'react';
import { useState } from 'react';

const Try = () => {

    const [address, setAddress] = useState(null);

    const getAddressFromLongLat = async () => {
        const URL = "http://nominatim.openstreetmap.org/reverse";
        const response = await axios.get(URL, {
            params: {
                format: "json",
                lat: 36.884804,
                lon: 30.704044
            },
            headers: {
                "Content-Type": "application/json; charset=UTF-8"
            }
        });
        const { data } = response; **// There is your mistake.**
        return {

            street: data.address.road   " "   data.address.house_number,
            cp: data.address.postcode,
            city: data.address.town,
            country: data.address.country_code.toUpperCase()
        };
    };

    useEffect(() => {
        const fetchFromLongLat = async () => {
            if (1 === 1) {
                const response = await getAddressFromLongLat();
                console.log("response from nominatim "   JSON.stringify(response, null, 4));
                setAddress(response);
            }
        };
        fetchFromLongLat();
    }, []);

    console.log(address)
    return (
        <div>try</div>
    )
}

export default Try

<script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.27.2/axios.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

CodePudding user response：

I'm not sure, but may be you don't need use async...await in second function. This is like tako inside tako. But you need just two tako in one tako bell.