My project is bundled on webpack (localhost:9000). I did post request to other local server(localhost:3000), now I need to take this data on localhost:9000/etc. I tried to do get request on localhost:3000, but it is not correct. Explain me please, what I have to do?
my request
function getReq() {
fetch('http://localhost:3000/test')
.then(response => {
response.json();
})
.then(data => {
// Work with JSON data here
console.log(data.body);
}).catch(err => {
// Do something for an error here
console.log("Error Reading data " + err);
})
}
getReq()
My server(I need to send req.body)
app.post('/post',(req,res) => {
console.log(req.body)
app.get('/test',(request,response)=>{
response.send(req.body)
})
res.send('ok')
})
I have a fetch API call that calls API back end and in return, I will get the response object with status code. What I am trying to do is base on return, I wanted to return the JSON response with status code. so that other part of the javascript can manipulate base on status code. My fetch function is as follow.
I have tried with as follow below, but it returns as a given screenshot. It gives me promise value which I didn't want to get.
export const createUser = ( posts ) => {
const apiRoute= "/api/register";
return window.fetch(`${apiRoute}`, {
"headers": headers,
method: "POST",
body: JSON.stringify(posts)
}).then(response => ({
'status' : response.status,
'data' : response.json()
}))
.catch(error => console.error('Error: ', error))
;
}
I know that it might be the duplicate from this post (Fetch api - getting json body in both then and catch blocks for separate status codes), but I do not want my data to return as a promise. Instead, I wanted to return fully constructed well form JSON data.
Something like this.
{status: 400, data: {id:1,name:Hello World}}
how can i achieve this?
"It gives me promise value"
That's right, as per the documentation.
You need to resolve that promise before resolving the outer promise.
For example
.then(response => {
return response.json().then(data => ({
status: response.status,
data
}))
})
Alternatively, use an async function
export const createUser = async ( posts ) => {
const apiRoute= "/api/register";
try {
const response = await window.fetch(apiRoute, {
headers,
method: "POST",
body: JSON.stringify(posts)
})
return {
status: response.status,
data: await response.json()
}
} catch (error) {
console.error('Error: ', error)
throw error
}
}
I'm trying to write a wrapper function for the JavaScript fetch command.
I took the example code from this post:
function fetchAPI(url, data, method = 'POST') {
const headers = {
'Authorization': `Token ${getAuthToken()}`,
};
return fetch(url, { headers, 'method': method, 'body': data })
.then(response => {
if (response.ok) {
const contentType = response.headers.get('Content-Type') || '';
if (contentType.includes('application/json')) {
return response.json().catch(error => {
return Promise.reject(new Error('Invalid JSON: ' + error.message));
});
}
if (contentType.includes('text/html')) {
return response.text().then(html => {
return {
'page_type': 'generic',
'html': html
};
}).catch(error => {
return Promise.reject(new Error('HTML error: ' + error.message));
});
}
return Promise.reject(new Error('Invalid content type: ' + contentType));
}
if (response.status === 404) {
return Promise.reject(new Error('Page not found: ' + url));
}
return response.json().then(res => {
// if the response is ok but the server rejected the request, e.g. because of a wrong password, we want to display the reason
// the information is contained in the json()
// there may be more than one error
let errors = [];
Object.keys(res).forEach((key) => {
errors.push(`${key}: ${res[key]}`);
});
return Promise.reject(new Error(errors)
);
});
}).catch(error => {
return Promise.reject(new Error(error.message));
});
};
And I'm calling it like this:
fetchAPI('/api/v1/rest-auth/password/change/', formData).then(response => {
console.log('response ', response);
});
Edit: I have modified the code to display information returned by the server if the request is ok but refused, for example because of an invalid password. You have to interrogate the response json if ok == false.
A valid URL fetch is fine. But if there is an error, I see an Unhandled Rejection (Error): error message.
Why is it that the rejects are unhandled even though they are in catch blocks? What's the secret sauce here?
The way to avoid an unhandled promise rejection, is to handle it:
fetchAPI('/api/v1/rest-auth/password/change/', formData).then(response => {
console.log('response ', response);
}).catch(error => {
// do something meaningful here.
});;
I am working on Reactjs redux on front-end and Rails API as a back-end.
So now I call API with Fetch API method but the problem is I cannot get readable error message like what I got inside the network tabs
this is my function
export function create_user(user,userInfoParams={}) {
return function (dispatch) {
dispatch(update_user(user));
return fetch(deafaultUrl + '/v1/users/',
{
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
method: "POST",
body: JSON.stringify(userInfoParams)
})
.then(function(response) {
console.log(response);
console.log(response.body);
console.log(response.message);
console.log(response.errors);
console.log(response.json());
dispatch(update_errors(response));
if (response.status >= 400) {
throw new Error("Bad response from server");
}
})
.then(function(json){
console.log("succeed json re");
// We can dispatch many times!
// Here, we update the app state with the results of the API call.
dispatch(update_user(json));
});
}
}
But when errors came I cannot figure out how to get readable response message like I got when I check on my browser network tabs
So this is what I got from the network tabs when I got errors.
My console
This is my rails code
def create
user = User.new(user_params)
if user.save
#UserMailer.account_activation(user).deliver_now
render json: user, status: 201
else
render json: { errors: user.errors }, status: 422
end
end
But I cannot find out how can I get that inside my function
Since the text is hidden inside promise within response object, it needs to be handled like a promise to see it.
fetch(bla)
.then(res => {
if(!res.ok) {
return res.text().then(text => { throw new Error(text) })
}
else {
return res.json();
}
})
.catch(err => {
console.log('caught it!',err);
});
Similar to your answer, but with a bit more explanation... I first check if the response is ok, and then generate the error from the response.text() only for the cases that we have a successful response. Thus, network errors (which are not ok) would still generate their own error without being converted to text. Then those errors are caught in the downstream catch.
Here is my solution - I pulled the core fetch function into a wrapper function:
const fetchJSON = (...args) => {
return fetch(...args)
.then(res => {
if(res.ok) {
return res.json()
}
return res.text().then(text => {throw new Error(text)})
})
}
Then when I use it, I define how to handle my response and errors as needed at that time:
fetchJSON(url, options)
.then((json) => {
// do things with the response, like setting state:
this.setState({ something: json })
})
.catch(error => {
// do things with the error, like logging them:
console.error(error)
})
even though this is a bit old question I'm going to chime in.
In the comments above there was this answer:
const fetchJSON = (...args) => {
return fetch(...args)
.then(res => {
if(res.ok) {
return res.json()
}
return res.text().then(text => {throw new Error(text)})
})
}
Sure, you can use it, but there is one important thing to bare in mind. If you return json from the rest api looking as {error: 'Something went wrong'}, the code return res.text().then(text => {throw new Error(text)}) displayed above will certainly work, but the res.text() actually returns the string. Yeah, you guessed it! Not only will the string contain the value but also the key merged together! This leaves you with nothing but to separate it somehow. Yuck!
Therefore, I propose a different solution.
fetch(`backend.com/login`, {
method: 'POST',
body: JSON.stringify({ email, password })
})
.then(response => {
if (response.ok) return response.json();
return response.json().then(response => {throw new Error(response.error)})
})
.then(response => { ...someAdditional code })
.catch(error => reject(error.message))
So let's break the code, the first then in particular.
.then(response => {
if (response.ok) return response.json();
return response.json().then(response => {throw new Error(response.error)})
})
If the response is okay (i.e. the server returns 2xx response), it returns another promise response.json() which is processed subsequently in the next then block.
Otherwise, I will AGAIN invoke response.json() method, but will also provide it with its own then block of code. There I will throw a new error. In this case, the response in the brackets throw new Error(response.error) is a standard javascript object and therefore I'll take the error from it.
As you can see, there is also the catch block of code at the very end, where you process the newly thrown error. (error.message <-- the error is an object consisting of many fields such as name or message. I am not using name in this particular instance. You are bound to have this knowledge anyway)
Tadaaa! Hope it helps!
I've been looking around this problem and has come across this post so thought that my answer would benefit someone in the future.
Have a lovely day!
Marek
If you came to this question while trying to find the issue because response.json() throws "Unexpected token at position..." and you can't find the issue with the JSON, then you can try this, basically getting the text and then parsing it
fetch(URL)
.then(async (response) => {
if (!response.ok) {
const text = await response.text()
throw new Error(text)
}
// Here first we convert the body to text
const text = await response.text()
// You can add a console.log(text), to see the response
// Return the JSON
return JSON.parse(text)
})
.catch((error) => console.log('Error:', error))
.then((response) => console.log(response))
I think you need to do something like this
export function create_user(user,userInfoParams={}) {
return function (dispatch) {
dispatch(update_user(user));
return fetch(deafaultUrl + '/v1/users/',
{
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
method: "POST",
body: JSON.stringify(userInfoParams)
})
.then(function(response) {
console.log(response);
console.log(response.body);
console.log(response.message);
console.log(response.errors);
console.log(response.json());
return response.json();
})
.then(function(object){
if (object.errors) {
dispatch(update_errors(response));
throw new Error(object.errors);
} else {
console.log("succeed json re");
dispatch(update_user(json));
}
})
.catch(function(error){
this.setState({ error })
})
}
}
You can access the error message with this way:
return fetch(deafaultUrl + '/v1/users/',
{
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
method: "POST",
body: JSON.stringify(userInfoParams)
})
.then(function(response) {
console.log(response);
console.log(response.body);
console.log(response.message);
console.log(response.errors);
console.log(response.json());
dispatch(update_errors(response));
if (response.status >= 400) {
throw new Error("Bad response from server");
}
})
.then(function(json){
console.log("succeed json re");
// We can dispatch many times!
// Here, we update the app state with the results of the API call.
dispatch(update_user(json));
})
// here's the way to access the error message
.catch(function(error) {
console.log(error.response.data.message)
})
;
The best choice is not to catch the error in the fetch because this will be useless:
Just in your api put a response with not code error
static GetInvoicesAllData = async (req,res) =>
{
try{
let pool = await new Connection().GetConnection()
let invoiceRepository = new InvoiceRepository(pool);
let result = await invoiceRepository.GetInvoicesAllData();
res.json(result.recordset);
}catch(error){
res.send(error);
}
}
Then you just catch the error like this to show the message in front end.
fetch(process.env.REACT_APP_NodeAPI+'/Invoices/AllData')
.then(respuesta=>respuesta.json())
.then((datosRespuesta)=>{
if(datosRespuesta.originalError== undefined)
{
this.setState({datosCargados:true, facturas:datosRespuesta})
}
else{ alert("Error: " + datosRespuesta.originalError.info.message ) }
})
With this you will get what you want.
You variables coming back are not in response.body or response.message.
You need to check for the errors attribute on the response object.
if(response.errors) {
console.error(response.errors)
}
Check here https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
You should actually be returning an error response code from the server and use the .catch() function of the fetch API
First you need to call json method on your response.
An example:
fetch(`${API_URL}`, {
method: 'post',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify(userInfoParams)
})
.then((response) => response.json())
.then((response) => console.log(response))
.catch((err) => {
console.log("error", err)
});
Let me know the console log if it didn't work for you.
Using react and webpack.. why does the code below result in an error: Uncaught (in promise) SyntaxError: Unexpected end of input(…)? Thanks
fetch(feedURL, {"mode": "no-cors"})
.then(response => response.json())
.then(function(data){
this.setState({
data: data
})
}.bind(this));
To better understand your error, add a catch case to your fetch request.
Also, if you use arrow functions, you don't need to bind(this);
fetch(feedURL, {"mode": "no-cors"})
.then(response => response.json())
.then(data => {
this.setState({
data: data
});
})
.catch(resp => {
console.error(resp);
});