I have an existing async function:
async doJSONGetRequest(getUrl, accessToken) {
return new Promise(function(resolve, reject) {
const reqHeaders = {
'Content-Type': 'application/json',
'Authorization': `Bearer ${accessToken}`,
};
console.info('url = ' + getUrl);
request.get({
url: getUrl,
headers: reqHeaders,
}, function(err, response) {
if (err) return reject(err);
try {
// console.debug(`response = ${response.body}`);
const parsed = JSON.parse(response.body);
return resolve(parsed);
} catch (err) {
return reject(err);
}
});
});
}
}
I'm trying to test it with Jasmine(v4).
Of course, I don't want this thing to actually make an HTTP request, so I tried rigging up a spy on the 'request' package's 'get' function in the 'beforeAll' section:
describe('RAPIDAPIService', function() {
beforeAll(async function() {
spyOn(request, 'get')
.and
.callFake(async (parameters) => {
if (parameters.url === 'http://localhost/api/getSomething') {
const rsp = {};
rsp.body = 'good stuff';
return rsp;
} else if (parameters.url === 'http://localhost/api/whoops') {
return new Error('401 not found');
} else {
return null;
}
});
});
it('doJSONGetRequest should run successfully', async () => {
expect(api.doJSONGetRequest).toBeDefined();
const res = await api.doJSONGetRequest('http://localhost/api/getSomething', '12345678');
expect(data).toEqual('good stuff');
});
it('doJSONGetRequest should resolve errors properly', async () => {
expect(api.doJSONGetRequest).toBeDefined();
const res = await api.doJSONGetRequest('http://localhost/api/whoops', '12345678');
const expectedError = new Error('401 not found');
expect(res).toEqual(expectedError);
});
Console log statements seem to indicate that I'm actually getting past / returning something from my "await" calls in the "it" tests. But the spies are actually working / detecting that the url's have been called.
(Note that I'm not including here other tests in the same file that do not make asynchronous calls and ARE working... just so you know that there's no problem accessing the actual "api" library and its functions.)
These two tests keep failing with "Error: Timeout - Async function did not complete within 5000ms". And like I said, it seems like they're not returning back to the tests from their calls to the doJSONGetRequest function.
Any thoughts?
Thanks!
I am thinking the issue is the mocking. request.get seems to take two parameters and I am thinking you need to call the 2nd parameter (callback function) once you are done so the resolve can be called.
Try this:
spyOn(request, 'get')
.and
// add callbackFunction as 2nd argument
.callFake((parameters, callbackFunction) => {
if (parameters.url === 'http://localhost/api/getSomething') {
const rsp = {};
rsp.body = 'good stuff';
callbackFunction(null, rsp);
} else if (parameters.url === 'http://localhost/api/whoops') {
callbackFunction({ error: '401 not found' }, {});
} else {
callbackFunction(null, null);
}
});
Related
Here's what I have going:
import 'whatwg-fetch';
function fetchVehicle(id) {
return dispatch => {
return dispatch({
type: 'FETCH_VEHICLE',
payload: fetch(`http://swapi.co/api/vehicles/${id}/`)
.then(status)
.then(res => res.json())
.catch(error => {
throw(error);
})
});
};
}
function status(res) {
if (!res.ok) {
return Promise.reject()
}
return res;
}
EDIT: The promise doesn't get rejected, that's what I'm trying to figure out.
I'm using this fetch polyfill in Redux with redux-promise-middleware.
Fetch promises only reject with a TypeError when a network error occurs. Since 4xx and 5xx responses aren't network errors, there's nothing to catch. You'll need to throw an error yourself to use Promise#catch.
A fetch Response conveniently supplies an ok , which tells you whether the request succeeded. Something like this should do the trick:
fetch(url).then((response) => {
if (response.ok) {
return response.json();
}
throw new Error('Something went wrong');
})
.then((responseJson) => {
// Do something with the response
})
.catch((error) => {
console.log(error)
});
The following login with username and password example shows how to:
Check response.ok
reject if not OK, instead of throw an error
Further process any error hints from server, e.g. validation issues
login() {
const url = "https://example.com/api/users/login";
const headers = {
Accept: "application/json",
"Content-Type": "application/json",
};
fetch(url, {
method: "POST",
headers,
body: JSON.stringify({
email: this.username,
password: this.password,
}),
})
.then((response) => {
// 1. check response.ok
if (response.ok) {
return response.json();
}
return Promise.reject(response); // 2. reject instead of throw
})
.then((json) => {
// all good, token is ready
this.store.commit("token", json.access_token);
})
.catch((response) => {
console.log(response.status, response.statusText);
// 3. get error messages, if any
response.json().then((json: any) => {
console.log(json);
})
});
},
Thanks for the help everyone, rejecting the promise in .catch() solved my issue:
export function fetchVehicle(id) {
return dispatch => {
return dispatch({
type: 'FETCH_VEHICLE',
payload: fetch(`http://swapi.co/api/vehicles/${id}/`)
.then(status)
.then(res => res.json())
.catch(error => {
return Promise.reject()
})
});
};
}
function status(res) {
if (!res.ok) {
throw new Error(res.statusText);
}
return res;
}
For me,
fny answers really got it all. since fetch is not throwing error, we need to throw/handle the error ourselves.
Posting my solution with async/await. I think it's more strait forward and readable
Solution 1: Not throwing an error, handle the error ourselves
async _fetch(request) {
const fetchResult = await fetch(request); //Making the req
const result = await fetchResult.json(); // parsing the response
if (fetchResult.ok) {
return result; // return success object
}
const responseError = {
type: 'Error',
message: result.message || 'Something went wrong',
data: result.data || '',
code: result.code || '',
};
const error = new Error();
error.info = responseError;
return (error);
}
Here if we getting an error, we are building an error object, plain JS object and returning it, the con is that we need to handle it outside.
How to use:
const userSaved = await apiCall(data); // calling fetch
if (userSaved instanceof Error) {
debug.log('Failed saving user', userSaved); // handle error
return;
}
debug.log('Success saving user', userSaved); // handle success
Solution 2: Throwing an error, using try/catch
async _fetch(request) {
const fetchResult = await fetch(request);
const result = await fetchResult.json();
if (fetchResult.ok) {
return result;
}
const responseError = {
type: 'Error',
message: result.message || 'Something went wrong',
data: result.data || '',
code: result.code || '',
};
let error = new Error();
error = { ...error, ...responseError };
throw (error);
}
Here we are throwing and error that we created, since Error ctor approve only string, Im creating the plain Error js object, and the use will be:
try {
const userSaved = await apiCall(data); // calling fetch
debug.log('Success saving user', userSaved); // handle success
} catch (e) {
debug.log('Failed saving user', userSaved); // handle error
}
Solution 3: Using customer error
async _fetch(request) {
const fetchResult = await fetch(request);
const result = await fetchResult.json();
if (fetchResult.ok) {
return result;
}
throw new ClassError(result.message, result.data, result.code);
}
And:
class ClassError extends Error {
constructor(message = 'Something went wrong', data = '', code = '') {
super();
this.message = message;
this.data = data;
this.code = code;
}
}
Hope it helped.
2021 TypeScript Answer
What I do is write a fetch wrapper that takes a generic and if the response is ok it will auto .json() and type assert the result, otherwise the wrapper throws the response
export const fetcher = async <T>(input: RequestInfo, init?: RequestInit) => {
const response = await fetch(input, init);
if (!response.ok) {
throw response;
}
return response.json() as Promise<T>;
};
and then I'll catch errors and check if they are an instanceof Response. That way TypeScript knows that error has Response properties such as status statusText body headers etc. and I can apply a custom message for each 4xx 5xx status code.
try {
return await fetcher<LoginResponse>("http://localhost:8080/login", {
method: "POST",
headers: {
Accept: "application/json",
"Content-Type": "application/json",
},
body: JSON.stringify({ email: "user#example.com", password: "passw0rd" }),
});
} catch (error) {
if (error instanceof Response) {
switch (error.status) {
case 401:
throw new Error("Invalid login credentials");
/* ... */
default:
throw new Error(`Unknown server error occured: ${error.statusText}`);
}
}
throw new Error(`Something went wrong: ${error.message || error}`);
}
and if something like a network error occurs it can be caught outside of the instanceof Response check with a more generic message i.e.
throw new Error(`Something went wrong: ${error.message || error}`);
The answer by #fny (the accepted answer) didn't work for me. The throw new Error() wasn't getting picked up by the .catch. My solution was to wrap the fetch with a function that builds a new promise:
function my_fetch(url, args) {
return new Promise((resolve, reject) => {
fetch(url, args)
.then((response) => {
response.text().then((body) => {
if (response.ok) {
resolve(body)
} else {
reject(body)
}
})
})
.catch((error) => { reject(error) })
})
}
Now every error and non-ok return will be picked up by the .catch method:
my_fetch(url, args)
.then((response) => {
// Do something with the response
})
.catch((error) => {
// Do something with the error
})
function handleErrors(response) {
if (!response.ok) {
throw Error(response.statusText);
}
return response;
}
fetch("https://example.com/api/users")
.then(handleErrors)
.then(response => console.log("ok") )
.catch(error => console.log(error) );
I wasn't satisfied with any of the suggested solutions, so I played a bit with Fetch API to find a way to handle both success responses and error responses.
Plan was to get {status: XXX, message: 'a message'} format as a result in both cases.
Note: Success response can contain an empty body. In that case we fallback and use Response.status and Response.statusText to populate resulting response object.
fetch(url)
.then(handleResponse)
.then((responseJson) => {
// Do something with the response
})
.catch((error) => {
console.log(error)
});
export const handleResponse = (res) => {
if (!res.ok) {
return res
.text()
.then(result => JSON.parse(result))
.then(result => Promise.reject({ status: result.status, message: result.message }));
}
return res
.json()
.then(result => Promise.resolve(result))
.catch(() => Promise.resolve({ status: res.status, message: res.statusText }));
};
I just checked the status of the response object:
$promise.then( function successCallback(response) {
console.log(response);
if (response.status === 200) { ... }
});
Hope this helps for me throw Error is not working
function handleErrors(response) {
if (!response.ok) {
return new Promise((resolve, reject) => {
setTimeout(() => {
reject({
status: response.status,
statusText: response.statusText,
});
}, 0);
});
}
return response.json();
}
function clickHandler(event) {
const textInput = input.value;
let output;
fetch(`${URL}${encodeURI(textInput)}`)
.then(handleErrors)
.then((json) => {
output = json.contents.translated;
console.log(output);
outputDiv.innerHTML = "<p>" + output + "</p>";
})
.catch((error) => alert(error.statusText));
}
Another (shorter) version that resonates with most answers:
fetch(url)
.then(response => response.ok ? response.json() : Promise.reject(response))
.then(json => doStuff(json)) //all good
//next line is optional
.catch(response => handleError(response)) //handle error
So, I have my route which console.logs 'undefined':
router.get("/validate-pin", async (req, res) => {
// restrict when done
try {
const { userId, pin } = req.query;
const isActivePin = await pinsDB.compareActivePin(userId, pin);
console.log(isActivePin)
return res.status(200).json(isActivePin);
} catch (error) {
console.log(error);
res.status(500).json({ error: "db error: ", error });
}
});
I have my compareActivePin method, which logs out the 'res' parameter, but for some reason doesn't return it:
async function compareActivePin(userId, received_pin) {
const active_pin = await db("account_pins").where({ userId, isActive: true });
const pinIsValidated = bcrypt.compareSync(
received_pin,
active_pin[0].account_pin
);
if (pinIsValidated) {
let skLocation = await db("sks").where({ userId }).select("url");
await readKey(skLocation[0].url, (res) => {
// console.log(res);
return res;
});
} else return false;
}
And I have my readKey method, which actually grabs the data I want my compareActivePin to return. This works like a charm.
const readKey = async (key, callback) => {
const aws = require("aws-sdk");
aws.config.update({
secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
accessKeyId: process.env.AWS_ACCESS_KEY_ID,
region: "us-east-2",
});
const s3 = new aws.S3();
const getParams = { Bucket: process.env.SK_BUCKET, Key: `${key}.txt` };
await s3.getObject(getParams, (err, data) => {
if (err) return err;
return callback(data.Body.toString());
});
};
So, just to recap. When I hit my endpoint, I pass in a userId and pin (strings). This calls the compareActivePin method which validates the pin and then, if the pin is valid, it then calls readKey, which grabs the file from S3 and returns the text within the file.
Like I said, I'm able to log it out to the console from within the readKey callback, but when I try to log it out as the returned value from the route, it comes back undefined.
Hoping someone could point me in the right direction.
Thanks...
I ended up answering my own question. I don't think it's possible to get a return value from the callback, so I ended up paring down the call from the database and sending the response from the readKey function using the router response object, like so:
//CompareActivePin Function
async function compareActivePin(userId, received_pin) {
const active_pin = await db("account_pins").where({ userId, isActive: true });
const pinIsValidated = bcrypt.compareSync(
received_pin,
active_pin[0].account_pin
);
return pinIsValidated;
}
//Router Call
router.get("/validate-pin", async (req, res) => {
// restrict when done
try {
const { userId, pin } = req.query;
const isActivePin = await pinsDB.compareActivePin(userId, pin);
if (isActivePin) {
let skLocation = await skDB.findUrl(userId);
readKeyFunc(skLocation[0].url, (result) => {
return res.status(200).json({ confirmed: isActivePin, key: result });
});
} else return res.status(401).json({ confirmed: isActivePin, key: null });
} catch (error) {
res.status(500).json({ error: "db error: ", error });
}
});
This also goes a long way toward keeping my database methods pure and separating my concerns.
Thanks, StackOverflow!
I want to block the function from returning value before promise resolves. And, pushheaders returns an promise obj instead of just value,
i just want pushheaders to return token which fetched from the firebase
import firebase from 'firebase';
let promise1 = new Promise((resolve, reject) => {
firebase.auth().currentUser.getIdToken().then(token => {
resolve(token);
}).catch(err => {
reject(err)
});
});
export function pushHeaders (ct) {
let b = await promise1.then(data => data);
let headerz = {
headers: {
Authorization: 'Bearer ' + b,
}
}
ct ? (headerz.headers['Content-Type'] = ct) : null;
return headerz;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.6.2/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/15.6.2/react-dom.min.js"></script>
There is no way to synchronize promises so with await your function needs to be async:
export async function pushHeaders(ct) {
const token = await promise1; // no need for a noop
const headers = {
headers: {
Authorization: `Bearer ${token}`,
...(ct ? { 'Content-Type': ct } : {}), // ECMAScript2018
},
};
return headers;
}
This also means that it returns a promise and not headers directly. To get the actual result you either need to use then or use asycn/await again on the callee.
I see you are using await, which is a typescript keyword, which is only allowed when you mark your function with Async, try that
export async function pushHeaders (ct) {
I am trying to call a function located in service class,and if that function returns data,one boolean variable sets true. I have 2 class as bollow:student.ts and service.ts:
// student.ts
public ngOnInit() {
this.config.load().then(() => {
this.service.getRecords().then(
function () { console.log("success getRecord");
this.loading = false; },
function () { console.log("failed getRecord");
this.loading = true; });
});
}
//service.ts
public getRecord(id: number): Promise<T> {
return this.getRecordImpl();
}
private getRecordsImpl(): Promise<T[]> {
let url = this.serviceUrl;
return this.http.get(url, this.getRequestOptionsWithToken())
.toPromise()
.then(res => {
this.records = this.extractData<T[]>(res);
for (var i = 0; i < this.records.length; i++) {
var record = this.records[i];
this.onRecord(record);
}
return this.records;
})
.catch(this.handleError);
}
by the now, records from service returns, but this.service.getRecords(); is undefined. and I can't use
.then
for handling succeed and failure actions.
I know that it is not good idea to make it synchronous. but think that being Asynchronous causes getRecords becomes undefined. What is the solution for handling that. I want it runs sequentially. and if service returns any records , variable initialize to false, otherwise it sets to true.
Many thanks for any help and guide.
I think your aproach is not correct, what is the point to make a promise synchronous ? If you really really want to do this I suggest you to dig in the Synchronous programming with es6 generators but usually the job is done much smother.
From your code I see that you are consuming your Promise by attaching .then() in the service. In this way you should create a new Promise.
private getRecordsImpl(): Promise<T[]> {
let url = this.serviceUrl;
return new Promise((resolve, reject) => {
this.http.get(url, this.getRequestOptionsWithToken())
.toPromise()
.then(res => {
this.records = this.extractData<T[]>(res);
for (var i = 0; i < this.records.length; i++) {
var record = this.records[i];
this.onRecord(record);
}
resolve(this.records);
})
.catch(this.handleError);
})
}
And in your code use:
this.service.getRecords().then(
function (records) { console.log("success getRecord");
this.loading = false; },
function (err) { console.log("failed getRecord");
this.loading = true; });
I have a http call to a remote server using the angular2/http and thats all working awesomely and such. But I'm having trouble with using the observables that it returns.
When I do my http calls, I'm going through 3 different components.
(for ease here ill just make the calls 3 different methods instead as it works out the same)
What I want to know if its possible to do, is use subscribe twice on the same observable or if there is a way that I can call some functions so I can add logging in the request rather than needing to add it at every location that I make a http call.
request(type: RequestMethod, url: string, data: any) {
let params: URLSearchParams = new URLSearchParams();
let req: RequestOptions;
let headers = new Headers();
for (let key in data) {
params.set(key, data[key]);
}
if (type === 0) {
req = new RequestOptions({
method: type,
search: params
});
} else {
headers.append('Content-Type', 'application/x-www-form-urlencoded');
req = new RequestOptions({
method: type,
body: params.toString(),
headers: headers
});
}
console.log('Http Request: ' + url);
console.log(req);
return this.http.request(this.testUrl + url, req)
.map((res: Response) => res.json());
// .subscribe(
// data => {
// console.log('Data Return for ' + url);
// console.log(data.data);
// // return data; //i removed this subscribe so i can
// }, //pass the map back through and
// err => { //use the subscribe later in the initial call
// this.logError(url, err);
// },
// () => {
// if (afterSuccess) {
// afterSuccess();
// }
// console.log('Completed '+ url);
// }
// );
}
logError(url: string, err: any) {
console.log('Error in call: ' + url);
console.log(err);
}
get(url: string, data: any) {
return this.request(RequestMethod.Get, url, data);
}
post(url: string, data: any) {
return this.request(RequestMethod.Post, url, data);
}
emailExists(email_address: string, user_type?: string) {
let data: any = {};
data.email_address = email_address;
data.service_provider_id = this.service_provider_id;
if (user_type) {
data.user_type = user_type;
}
return this.get('emails/email-address/exists', data);
}
ngOnInit() {
this.emailExists('an.email#gmail.com').subscribe(data => {
this.email = data.data;
console.log('in Signin');
console.log(this.email);
}, err => {
console.log(err);
}, () => {
});
}
In the request method I want to be able to call a console.log to print out the url that was used and print the data received from the server or any errors.
I know I could add it to the success and error portions of the subscribe in the emailExists() call in ngOnInit() but that would mean I would need to put those in every single call throughout the app.
Thanks in advance for your help and time.
You could leverage the do, catch and finally operators of observables to do that.
Here is a sample:
return this.http.request(this.tpayUrl + url, req)
.map((res: Response) => res.json())
.do(data => {
console.log('Data Return for ' + url);
console.log(data.data);
})
.catch(err => {
this.logError(url, err);
return Observable.throw(err);
})
.finally(() => {
if (afterSuccess) {
afterSuccess();
}
console.log('Completed '+ url);
});