const test = order.restaurantId;
console.log(test); //here test == 3
const getAvailableHours = async () =>{
console.log(test); //test == undefined
await fetch(`API Address`, {
method: 'POST',
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
},
})
.then(response => {
return response.json();
})
.then(responseText => {
console.log(responseText);
})
.catch(error => {
console.log(error);
});
}
Hi, I am trying to fetch data from API by using restaurant ID but when I'm passing the ID to async it becomes undefined.
I am new in React.js, anyone has any ideas?
async await syntax allows you to avoid .then method, so you can handle promises with a more readable syntax. With try catch blocks you can handle errors, try this:
const getAvailableHours = async () => {
try {
let response = await fetch('https://api-address-goes-here/', {
method: 'POST',
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
}
});
let responseText = await response.json();
return responseText;
} catch (err) {
console.log(err)
}
}
Related
I am trying to get pub locations data from MYSQL server and my fetch function works well. But after that, this try-catch block does not return anything. I also tried without try-catch block but it does not change anything
getPubsFromDatabase = async () => {
let response = await fetch(fetchDataUrl, {
method: 'POST',
headers:
{
'Accept': 'application/json',
'Content-Type': 'application/json',
},
});
try{
let json = await response.json();
console.log(json)
return json;
}
catch (error) {
console.log(error);
}
}
And here, I am trying to get the return value of the function. But in this version, I cannot even see any console.log output. What I mean by the version is, if I put 2nd line out of the async block without "await" keyword, I can see the console.log but I it gives "undefined" then.
(async () => {
const locationsData = await getPubsFromDatabase();
console.log(locationsData)
})()
You can use then and catch in the function fetch.
const getPubsFromDatabase = () => {
return fetch(fetchDataUrl, {
method: 'POST',
headers:
{
'Accept': 'application/json',
'Content-Type': 'application/json',
},
}).then(async (response) => {
const json = await response.json().then((data)=>{
return data;
}).catch((err)=>{
console.log('error from json method: ',err);
return { error: {
message: 'error from json method',
object: err
}};
});
console.log(json);
return json;
}).catch((error) => {
console.log('error from request: ', error);
return {
error: {
message: 'error from request', object: error
}
};
});
}
And when you use the method getPubsFromDatabase would be of the next way:
(async () => {
const locationsData = await getPubsFromDatabase();
console.log(locationsData);
})()
You can use Promise to return either result or error, In the example given below i have used axios library but you can also try same with fetch api
For Example
export const getData = () => {
return new Promise((resolve, reject) => {
const url = ApiConstant.BASE_URL + ApiConstant.ENDPOINT;
const API_HEADER = {
"Authorization": token,
};
axios
.get(url, {
headers: API_HEADER,
})
.then((res) => {
resolve(res.data);
})
.catch((error) => {
// handle error
reject(error);
console.log(error);
});
})
}
You can call the above function in component or screen like this:
getData().then(
(data) => {
}
).catch(
error => {
console.log(error)
}
)
I solved the problem by instead of returning the value from the function, I set the value inside the function. This seems to work now.
const [locationsData, setLocationsData] = useState();
getPubsFromDatabase = async () => {
let response = await fetch(fetchDataUrl, {
method: 'POST',
headers:
{
'Accept': 'application/json',
'Content-Type': 'application/json',
},
});
try{
let json = await response.json();
setLocationsData(json); // Here, I changed the value of the locationsData instead of returning
}
catch (error) {
console.log(error);
}
}
And to call the function:
useEffect(()=> {
getPubsFromDatabase();
},[])
import fetch from "node-fetch";
const URL_API = `https://jsonmock.hackerrank.com/api/countries?`;
async function getResponse() {
let response = await fetch(URL_API, {
method: "GET",
headers: {
"Content-type": "application/json",
},
})
.then((response) => {
return response.json();
})
.then((data) => {
console.log(data);
})
.catch((error) => {
// handle error
console.error(`The unknown error has occurred: ${error}`);
});
}
getResponse();
async function getCapitalCity(country) {
const data = await response.json(); //error mentioned here
for (let info in data) {
console.log(info);
if (info.name === country) {
return info.capital;
} else {
return -1;
}
}
}
console.log(getCapitalCity("Afghanistan"));
working on retrieving a json object. I am trying to use the response object from getResponse() in getCapitalCity() based on country entered (string). My problem is knowing how to use the response in the second function. currently get a promise rejected reference error: response is not defined. thank you in advance.
I have reorganized Your code and added different loops.
const URL_API = `https://jsonmock.hackerrank.com/api/countries?`;
async function getResponse() {
let response = await fetch(URL_API, {
method: 'GET',
headers: {
'Content-type': 'application/json'
}
})
try {
return await response.json();
} catch (error) {
// handle error
console.error(`The unknown error has occurred: ${error}`);
}
}
getResponse();
async function getCapitalCity(country) {
const dat = await getResponse();
const capital = dat.data.filter((item) => item.name === country).map(item => item.capital);
return capital;
}
getCapitalCity('Afghanistan').then(items => console.log('capital: ', items))
I have routes set up for a local api. So I am trying to retrieve the api data console log just the data. But whenever I run my code it console logs the entire promise. Any ideas on how to help?
This is my code:
const onPageLoad = async () => {
const response = await fetch(`/api/project/projects`, {
method: 'GET',
headers: { 'Content-Type': 'application/json' },
})
if (response.ok) {
console.log(response.json())
} else {
console.error(err)
}
}
onPageLoad();
This is what shows in the console log:
You can await the promise from response.json() to get its value:
const onPageLoad = async () => {
const response = await fetch(`/api/project/projects`, {
method: 'GET',
headers: { 'Content-Type': 'application/json' },
})
if (response.ok) {
let value = await response.json();
console.log(value);
// potentially do something else with value
return value;
} else {
console.log('fetch() promise succeeded, but not with response.ok', response.status);
throw new Error(`Got status ${response.status}`);
}
}
onPageLoad().then(() => {
console.log('all done');
}).catch(err => {
console.log(err);
});
How to use response from fetch api?
i try to return my response, but when i try to print this values in my function, i get undefined,
can someone tell me how to use this response in different function?
my response is an json of nested objects
async fetchData() {
const url = `...`;
fetch(url, {
method: 'post',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify({
//
})
}).then((response) => response.json())
.then(response => {;
console.log(response) //correct response
return response;
})
}
async getDataFromFetchApi() {
const data= await this.fetchData();
console.log(data); // undefined
if(data != undefined){
throw new BadRequestException();
}
return data;
}
thanks for any help
Bottom line, an async function must return a promise to work correctly. fetchData has no return value. The return response is inside of a .then, and doesn't apply to the fetchData function itself.
For the above code, the fewest modifications is simply to return fetch(...) in your fetchData function, like this:
async fetchData() {
const url = `...`;
return fetch(/* ... */)
.then((response) => response.json())
.then(response => {
console.log(response) //correct response
return response;
})
}
Alternatively you could use the async/await syntax for all it's worth, and get rid of your .thens, like this:
async fetchData() {
const url = `...`;
const resp = await fetch(/* ... */);
const json = await resp.json();
console.log(json);
return json;
}
You have to return data in the scope of fetchData function:
async fetchData() {
const url = `...`;
const response = await fetch(url, {
method: 'post',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify({
//...
})
});
return response;
}
I have an arrow function which returns some data from an api call. i want to wrap it up inside a try catch block like
const fetchEmployees = () => (
try{
fetch('http://localhost:6873/api/values', {
method: 'GET',
headers: {
'content-type': 'application/json'
}
})
.then(response => response.json())
.then(names => { return names })
} catch (error) {
return error;
}
)
How could i do that? The perfectly working arrow function I have is
const fetchEmployees = () => (
fetch('http://localhost:6873/api/values', {
method: 'GET',
headers: {
'content-type': 'application/json'
}
})
.then(response => response.json())
.then(names => names )
)
You can't use try catch on fetch because fetch is async while try catch is sync. Therefore your try catch will always pass. if we assume that you received response, and .json() fails, in second then first parameter is success function second one is fail function that executes when .json() fails
const fetchEmployees = () => (
fetch('http://localhost:6873/api/values', {
method: 'GET',
headers: {
'content-type': 'application/json'
}
})
.then(response => response.json())
.then(names => names, error => "json failed" )
)
fetchEmployees().then(success => {}, error => {})
Like this when you call fetchEmployees in first function will be executed if everything succeed, otherwise second will execute with error response, in this case hard coded string "json failed"
Turn your function into an async one:
const fetchEmployees = async () => {
try {
const response = await fetch("http://localhost:6873/api/values", {
method: "GET",
headers: {
"content-type": "application/json"
}
});
const names = await response.json();
return names;
} catch (error) {
return error;
}
};
Try to use async/await
const fetchEmployees = async () => {
try {
let response = await fetch('http://localhost:6873/api/values', {
method: 'GET',
headers: {
'content-type': 'application/json'
}
});
let json = await response.json();
return json;
} catch (error) {
return error
}
}