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Javascript in VueJs: how to return data object from async fetch instead of Promise

I have this action in store
actions: {
testLogin(context, credentials) {
const loginService = new FetchClient();
let d = loginService.post('login', credentials);
console.log(d);
},
and this function in another class imported to store
async post(endpoint, params) {
await fetch(this.url + endpoint, {
'method': 'POST',
headers: this.headers,
body: JSON.stringify(params),
})
.then(response => {
return response.json();
})
.then( (data) => {
this.returnData = data.data;
})
.catch(error => {
console.log(error);
});
return this.returnData;
}
And I get Promise {<pending>} which I can extract data from inside the fetch class but can't access data if I'm in the store because it's a Promise not an object. How can I solve this?

Put the return statement inside the second then block:
async post(endpoint, params) {
await fetch(this.url + endpoint, {
'method': 'POST',
headers: this.headers,
body: JSON.stringify(params),
})
.then(response => {
return response.json();
})
.then( (data) => {
this.returnData = data.data;
return this.returnData;
})
.catch(error => {
console.log(error);
});
}
I would even recommend you use the following code for better legibility:
async post(endpoint, params) {
const response = await fetch(this.url + endpoint, {
'method': 'POST',
headers: this.headers,
body: JSON.stringify(params),
})
if (!response.ok) {
const message = `An error has occured: ${response.status}`;
throw new Error(message);
}
const resp_data = await response.json()
return resp_data.data
}
Then call your method like so:
post(endpoint, params)
.then(data => {// do something with data})
.catch(error => {
error.message; // 'An error has occurred: 404'
});
refer to this async/await guide

Can you try:
async testLogin(context, credentials) {
const loginService = new FetchClient();
let d = await loginService.post('login', credentials);
console.log(d);
}

As #Ayudh mentioned, try the following code:
async post(endpoint, params) {
try{
let response = await fetch(this.url + endpoint, {
'method': 'POST',
headers: this.headers,
body: JSON.stringify(params),
});
let data = await response.json();
this.returnData = data.data;
}catch(e){
console.log(e);
}
return this.returnData;
}

javascript undefined value using fetch in function

If I call this function:
async function delete_get_note() {
let query = {
'command': 'delete_get_content',
'note_id': input_note_id.value
}
let response = await fetch(
'../api/api.php',
{
method: 'POST',
headers: {'Content-Type': 'application/json;charset=utf-8'},
body: JSON.stringify(query)
}
);
let result = await response.json();
log.innerHTML = result.log;
}
log displays the content of the json returned by my server. However, if I try to encapsulate the call to fetch in a function:
async function json_exchange(object) {
let response = await fetch(
'../api/api.php',
{
method: 'POST',
headers: {'Content-Type': 'application/json;charset=utf-8'},
body: JSON.stringify(object)
});
return await response.json;
}
And call:
async function delete_get_note() {
let query = {
'command': 'delete_get_content',
'note_id': input_note_id.value
}
let result = await json_exchange(query);
log.innerHTML = result.log;
}
Then log displays undefined.
What did I get wrong when I tried to put the call to fetch in a function ?

You forgot to add the parentheses to the json call:
return await response.json;
-->
return await response.json()
Tip: You can use TypeScript checking to easily detect such errors:

i'm having problems using axios and making requests to a api

const getCustomers = async (token) => {
try {
const response = await axios.get(`${base_url}/customers`, { headers: { 'Authorization': `Bearer ${token}`} })
return response.data
} catch(error) {
logger.error(error)
}
i'm using axios to make a request to an api, and i keep getting the same error.
error: undefined {"config":{"url":"https://api.contaazul.com/v1/customers","method":"get","headers":{"Accept":"application/json","Authorization":"Bearer EU5KBm8ft1ZB4vFy9I89xYQWnzqcbULS","User-Agent":"axios"},"transformRequest":[null],"transformResponse":[null],"timeout":0,"xsrfCookieName":"XSRF-TOKEN","xsrfHeaderName":"X-XSRF-TOKEN","maxContentLength":-1},"code":"HPE_INVALID_HEADER_TOKEN"}
already tried deleting node_modules and using other versions of node

Try this
const getCustomers = async (token) => {
await axios.get(`${base_url}/customers`, {
headers: {
"Authorization": `Bearer ` + token
}
})
.then(response => {
return response.data;
})
.catch(err => {
console.log(err)
});
}

Return resolved promise value

const displayCharacters = async () => {
if(filteredCharacters !== 'default'){
const a = filteredCharacters.map(e => e.name);
const options = {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({ 'data' : a })
};
const b = await fetch("/image",options).then(res => res.json())
return b;
}else{
return "yikes";
}
}
console.log(displayCharacters());
I have this fetch request but when I log the results this is what i see :
Promise {<resolved>: "yikes"}
__proto__: Promise
[[PromiseStatus]]: "resolved"
[[PromiseValue]]: "yikes"
I just want the promiseValue and not this whole thing around it. How do i do this?

the async function returns a promise instantly, without waiting for the promise to resolve. You may instead console.log inside the function:
const displayCharacters = async () => {
if(filteredCharacters !== 'default'){
const a = filteredCharacters.map(e => e.name);
const options = {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({ 'data' : a })
};
try {
const b = await fetch("/image",options).then(res => res.json());
console.log(b);
//the better practice is however, to do like:
const b = await fetch("/image",options)
const result = await b.json();
console.log(result );
}
catch(err) {
console.log(err);
}
}else{
console.log("yikes");
}
}
displayCharacters();

The best way that i know to use fetch goes something like this:
const displayCharacters = async () => {
if(filteredCharacters !== 'default'){
const a = filteredCharacters.map(e => e.name);
const options = {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({ 'data' : a })
};
const b = await fetch("/image",options)
.then(res => {
// Handle API Errors
if (!res.ok) {
throw Error(res.statusText);
}
// Return if no errors
return res.json();
})
// this is the data you want
.then(data => data)
// it will only reject on network failure or if anything prevented the request from completing
.catch(error => {
console.log(error.message)
});
return b;
}else{
return "yikes";
}
}
Basically you chain two thens and a catch to completely understand the response
- the first then checks for api level errors
- second then gets you the data
- catch is invoked in case when it is not able to reach the api itself like connection issues

Async/Await in fetch() how to handle errors

I have stripe async code in my React app, and trying to add error handling in my code but have no idea how to handle it. i know how to do it with .then() but async/await is new to me
EDITED
added .catch() i got errors in network tab in response tab.
but i can log it to console?
submit = async () => {
const { email, price, name, phone, city, street, country } = this.state;
let { token } = await this.props.stripe
.createToken({
name,
address_city: city,
address_line1: street,
address_country: country
})
.catch(err => {
console.log(err.response.data);
});
const data = {
token: token.id,
email,
price,
name,
phone,
city,
street,
country
};
let response = await fetch("/charge/pay", {
method: "POST",
headers: {
"Content-Type": "application/json"
},
body: JSON.stringify(data)
}).catch(err => {
console.log(err.response.data);
});
console.log(response);
if (response.ok)
this.setState({
complete: true
});
};
thanks

Fetch detects only network errors. Other errors (401, 400, 500) should be manually caught and rejected.
await fetch("/charge/pay", headers).then((response) => {
if (response.status >= 400 && response.status < 600) {
throw new Error("Bad response from server");
}
return response;
}).then((returnedResponse) => {
// Your response to manipulate
this.setState({
complete: true
});
}).catch((error) => {
// Your error is here!
console.log(error)
});
If you are not comfortable with this limitation of fetch, try using axios.

var handleError = function (err) {
console.warn(err);
return new Response(JSON.stringify({
code: 400,
message: 'Stupid network Error'
}));
};
var getPost = async function () {
// Get the post data
var post = await (fetch('https://jsonplaceholder.typicode.com/posts/5').catch(handleError));
// Get the author
var response = await (fetch('https://jsonplaceholder.typicode.com/users/' + post.userId).catch(handleError));
if (response.ok) {
return response.json();
} else {
return Promise.reject(response);
}
};

You can either use try/catch just like normal, imperative programming:
try {
let response = await fetch("/charge/pay", {
method: "POST",
headers: {
"Content-Type": "application/json"
},
body: JSON.stringify(data)
});
} catch(error) {
// Error handling here!
}
Or you can mix-and-match .catch() just like you do with promises:
let response = await fetch("/charge/pay", {
method: "POST",
headers: {
"Content-Type": "application/json"
},
body: JSON.stringify(data)
}).catch(function(error) {
// Error handling here!
});

Wrap your await with try catch.
try {
let response = await fetch("/charge/pay", {
method: "POST",
headers: {
"Content-Type": "application/json"
},
body: JSON.stringify(data)
});
console.log(response);
} catch (error) {
console.log(error);
}

This works if server returns { message: "some error" } but I'm trying to get it to support res.statusText too:
const path = '/api/1/users/me';
const opts = {};
const headers = {};
const body = JSON.stringify({});
const token = localStorage.getItem('token');
if (token) {
headers.Authorization = `Bearer ${token}`;
}
try {
const res = await fetch(path, {
method: opts.method || 'GET',
body,
headers
});
if (res.ok) {
return await (opts.raw ? res.text() : res.json());
}
const err = await res.json();
throw new Error(err.message || err.statusText);
} catch (err) {
throw new Error(err);
}

async function loginWithRedirect(payload: {
username: string;
password: string;
}) {
const resp = await (await fetch(`${env.API_URL}/api/auth/login`, {
method: "POST",
headers: {"Content-Type": "application/json"},
body: JSON.stringify(payload),
credentials: "include",
})).json();
if (resp.error) {
dispatch({type: "ERROR", payload: resp.error.message});
} else {
dispatch({type: "LOGIN", payload: resp});
}
}

If response.ok is false you can throw an error then chain catch method after calling your function as follows
async function fetchData(){
const response = await fetch("/charge/pay", {
method: "POST",
headers: {
"Content-Type": "application/json"
},
body: JSON.stringify(data)
});
if(!response.ok){
const message = `An error occured: ${response.status}`;
throw new Error(message);
}
const data = await response.json();
return data;
}
fetchData()
.catch(err => console.log(err.message));

I write promise function for using fetch in async await.
const promisyFetch = (url, options) =>
new Promise((resolve, reject) => {
fetch(url, options)
.then((response) => response.text())
.then((result) => resolve(result))
.catch((error) => reject(error));
});
By the way i can use it easly in async with try catch
const foo = async()=>{
try {
const result = await promisyFetch('url' requestOptions)
console.log(result)
} catch (error) {
console.log(error)
}
}
It was simple example, you could customize promisyFetch function and request options as you wish.

const data = {
token: token.id,
email,
price,
name,
phone,
city,
street,
country
};
axios
.post("/charge/pay", data)
.then(res => {
console.log(res);
})
.catch(err => {
console.log(err.response.data);
});