I am running the Bitfinex Websocket connection from node.js server using express.
I have an API endpoint so that I ask for the specific book from the link (e.g http://localhost:4000/BTC-USD/buy/100)
The problem is that when I try to make the connection from the app.get the websocket doesn't respond
It only responds from outside. The problem is that, that way I cant pass the parameter so I can establish the proper connection. The code I can't perform
app.get("/:pair/:type/:amount", async (req,res) => {
let { pair, type, amount } = req.params;
try {
wsConnection(pair);
wsMessageHandler()
const result = await simulateEffectivePrice({ pair, type, amount })
res.send({ "effectivePrice" : result })
} catch (error) {
res.send({"error" : error.message})
}
})
The code that works:
wsConnection();
wsMessageHandler()
app.get("/:pair/:type/:amount", async (req,res) => {
let { pair, type, amount } = req.params
try {
// if (type !== "buy" || type !== "sell") throw new Error ("wrong type input")
const result = await simulateEffectivePrice({pair,type,amount})
res.send({ "effectivePrice" : result })
} catch (error) {
res.send({"error" : error.message})
}
})
The wsConnection functions is this, (it requires the book you want to receive information from)
const wsConnection = async () => {
let msg = JSON.stringify({
event: 'subscribe',
channel: 'book',
symbol: 'tBTCUSD',
// len: "25"
})
try {
w.on('open', () => {
w.send(JSON.stringify({ event: 'conf', flags: 65536 + 131072 }))
w.send(msg)
})
} catch (error) {
throw new Error("BUILD CUSTOM ERROR")
}
}
"symbol" would need to be the parameter specified on the endpoint by the user
Thank you very much
I am pretty much new to node / express and following a youtube tutorial to build a MERN Stack app. But my node server is giving this error
I tried restarting server many times it happening again and again. I got the idea it happens when we send two responses for one request but I don't think its the case here.
Btw here is the route it is pointing to in the error (in the try catch error response line)
// GET RANDOM
router.get("/random", verify, async (req, res) => {
const type = req.query.type;
let movie;
try {
if (type === "series") {
movie = await Movie.aggregate([
{ $match: { isSeries: true } },
{ $sample: { size: 1 } },
]);
} else {
movie = await Movie.aggregate([
{ $match: { isSeries: false } },
{ $sample: { size: 1 } },
]);
}
res.status(200).json(movie); //checked here by console logging it comes here only once
} catch (err) {
res.status(500).json(err); //the error pointing to this line
}
});
Just in case, here is the verify function code:
function verify(req,res,next) {
const authHeader = req.headers.token;
if(authHeader){
const token = authHeader.split(' ')[1];
jwt.verify(token,process.env.SECRET_KEY,(err,user) => {
if(err) res.status(403).json("Token is not valid");
req.user = user;
next();
})
} else{
return res.status(401).json("Unauthorized");
}
}
Below is the piece of code i have written , to get the result but null in response
I am using selectObjectContent api to get the results with the simple SQL query
const bucket = 'myBucketname'
const key = 'file.json.gz'
const query = "SELECT * FROM s3object "
const params = {
Bucket: bucket,
Key: key,
ExpressionType: "SQL",
Expression: query,
InputSerialization: {
CompressionType: "GZIP",
JSON: {
Type: "LINES"
},
},
OutputSerialization: {
JSON: {
RecordDelimiter: ","
}
}
}
s3.selectObjectContent(params,(err, data) => {
if (err) {
console.log(data)
} else {
console.log(err)
}
})
I have found the solution to it. was logging error when getting successfull result/data , so corrected it below. Also i have found the way to read stream buffer data
s3.selectObjectContent(params,(err, data) => {
if (err) {
console.log(err)
} else {
console.log(data)
}
})
const eventStream = data.Payload;
// Read events as they are available
eventStream.on('data', (event) => {
if (event.Records) {
// event.Records.Payload is a buffer containing
// a single record, partial records, or multiple records
var records = event.Records.Payload.toString();
console.log( records )
} else if (event.Stats) {
console.log(`Processed ${event.Stats.Details.BytesProcessed} bytes`);
} else if (event.End) {
console.log('SelectObjectContent completed');
}
I have recently been developing a MERN application and I have recently came into the trouble that express is saying that I am setting headers after they are sent.
I am using mongo db and trying to update a user profile.
I have tried to comment out my res.send points to find the issue but I have failed to do so.
Here is my post method for updating the user profile:
app.post("/api/account/update", (req, res) => {
const { body } = req;
// Validating and Checking Email
if (body.email) {
var email = body.email;
email = email.toLowerCase();
email = email.trim();
body.email = email;
User.find(
{
email: body.email
},
(err, previousUsers) => {
if (previousUsers.length > 0) {
return res.send({
success: false,
message:
"Error: There is already another account with that email address"
});
} else {
}
}
);
}
// Validating Names Function
function checkName(name) {
var alphaExp = /^[a-zA-Z]+$/;
if (!name.match(alphaExp)) {
return res.send({
success: false,
message: "Error: Names cannot contain special characters or numbers"
});
}
}
checkName(body.firstName);
checkName(body.lastName);
// Making sure that all fields cannot be empty
if (!body.email && !body.firstName && !body.lastName) {
return res.send({
success: false,
message: "Error: You cannot submit nothing"
});
}
// Getting User ID from the current session
UserSession.findById(body.tokenID, function(err, userData) {
// Finding User ID using the current users session token
if (userData.isDeleted) {
return res.send({
success: false,
message:
"Error: Session token is no longer valid, please login to recieve a new one"
});
}
// Deleting the token ID from the body object as user table entry doesnt store tokens
delete body.tokenID;
// Finding the user profile and updating fields that are present
User.findByIdAndUpdate(userData.userId, body, function(err, userInfo) {
if (!err) {
return res.send({
success: true,
message: "Success: User was updated successfully"
});
}
});
});
});
This is the call that I am doing to the backend of the site:
onUpdateProfile: function(fieldsObj) {
return new Promise(function(resolve, reject) {
// Get Session Token
const obj = getFromStorage("the_main_app");
// Defining what fields are getting updated
fieldsObj.tokenID = obj.token;
// Post request to backend
fetch("/api/account/update", {
method: "POST",
headers: {
"Content-Type": "application/json"
},
body: JSON.stringify(fieldsObj)
})
.then(res => {
console.log("Verify Token - Res");
return res.json();
})
.then(json => {
console.log("Verify Token JSON", json);
if (json.success) {
window.location.href = `/manage-account?success=${json.success}`;
} else {
window.location.href = `/manage-account?success=${json.success}`;
}
});
});
}
Here is my error message that I am getting:
Error: Can't set headers after they are sent.
at validateHeader (_http_outgoing.js:491:11)
at ServerResponse.setHeader (_http_outgoing.js:498:3)
at ServerResponse.header (C:\Users\kieran.corkin\Desktop\Projects\Mern Template Final\mern-cra-and-server\server\node_modules\express\lib\response.js:767:10)
at ServerResponse.send (C:\Users\kieran.corkin\Desktop\Projects\Mern Template Final\mern-cra-and-server\server\node_modules\express\lib\response.js:170:12)
at ServerResponse.json (C:\Users\kieran.corkin\Desktop\Projects\Mern Template Final\mern-cra-and-server\server\node_modules\express\lib\response.js:267:15)
at ServerResponse.send (C:\Users\kieran.corkin\Desktop\Projects\Mern Template Final\mern-cra-and-server\server\node_modules\express\lib\response.js:158:21)
at C:\Users\kieran.corkin\Desktop\Projects\Mern Template Final\mern-cra-and-server\server\routes\api\account.js:270:22
at C:\Users\kieran.corkin\Desktop\Projects\Mern Template Final\mern-cra-and-server\server\node_modules\mongoose\lib\model.js:4641:16
at process.nextTick (C:\Users\kieran.corkin\Desktop\Projects\Mern Template Final\mern-cra-and-server\server\node_modules\mongoose\lib\query.js:2624:28)
at _combinedTickCallback (internal/process/next_tick.js:131:7)
at process._tickCallback (internal/process/next_tick.js:180:9)
[nodemon] app crashed - waiting for file changes before starting...
Can anyone help me with this?
EDIT
I have changed my code, this seems to now work however I feel like its a little messy when put together. Any refactoring tips?
Code:
app.post("/api/account/update", (req, res) => {
// Preform checks on data that is passed through
const { body } = req;
var messages = {
ExistedUser:
"Error: There is already another account with that email address",
NameFormat: "Error: Names cannot contain special characters or numbers",
BlankInputs: "Error: You cannot submit nothing",
accountLoggedOut:
"Error: Session token is no longer valid, please login to recieve a new one",
successfullyUpdated: "Success: User was updated successfully"
};
var usersFound;
if (body.email) {
var email = body.email;
email = email.toLowerCase();
email = email.trim();
body.email = email;
User.find(
{
email: body.email
},
(err, UserCount) => {
usersFound = UserCount;
}
);
}
function capitalize(text) {
return text.replace(/\b\w/g, function(m) {
return m.toUpperCase();
});
}
if (body.firstName) {
body.firstName = capitalize(body.firstName);
}
if (body.lastName) {
body.lastName = capitalize(body.lastName);
}
//Making sure that all fields cannot be empty
if (!body.email && !body.firstName && !body.lastName) {
return res.send({
success: false,
message: messages.BlankInputs
});
}
// Getting User ID from the current session
UserSession.findById(body.tokenID, function(err, userData) {
// Finding User ID using the current users session token
if (userData.isDeleted) {
return res.end({
success: false,
message: messages.accountLoggedOut
});
}
if (userData) {
// Deleting the token ID from the body object as user table entry doesnt store tokens
delete body.tokenID;
// Finding the user profile and updating fields that are present
User.findByIdAndUpdate(userData.userId, body, function(err, userInfo) {
if (userInfo) {
if (!usersFound.length > 0) {
return res.send({
success: true,
message: messages.successfullyUpdated
});
} else {
return res.send({
success: false,
message: messages.ExistedUser
});
}
}
});
}
});
});
You're calling res.send() twice. res.send() ends the process. You ought to refactor such that you call res.write() and only call res.send() when you're done.
This StackOverflow link describes the difference in more detail. What is the difference between res.send and res.write in express?
I believe this is happening, as you're trying to send a response after the first / initial response has already been sent to the browser. For example:
checkName(body.firstName);
checkName(body.lastName);
Running this function twice is going to try and yield 2 different "response" messages.
The product of a single route, should ultimately be a single response.
Thanks for all your help on this issue.
Here is my final code that allowed it to work.
I have also tried to "refactor" it too. Let me know if you'd do something else.
app.post("/api/account/update", (req, res) => {
const { body } = req;
console.log(body, "Logged body");
// Defining objects to be used at the end of request
var updateUserInfo = {
userInfo: {},
sessionToken: body.tokenID
};
var hasErrors = {
errors: {}
};
// Checking that there is at least one value to update
if (!body.email && !body.firstName && !body.lastName) {
var blankError = {
success: false,
message: "Error: You cannot change your details to nothing"
};
hasErrors.errors = { ...hasErrors.errors, ...blankError };
} else {
console.log("Normal Body", body);
clean(body);
console.log("Cleaned Body", body);
updateUserInfo.userInfo = body;
delete updateUserInfo.userInfo.tokenID;
}
// Function to check if object is empty
function isEmpty(obj) {
if (Object.keys(obj).length === 0) {
return true;
} else {
return false;
}
}
// Function to remove objects from body if blank
function clean(obj) {
for (var propName in obj) {
if (obj[propName] === "" || obj[propName] === null) {
delete obj[propName];
}
}
}
// Checking and Formatting Names Given
function capitalize(text) {
return text.replace(/\b\w/g, function(m) {
return m.toUpperCase();
});
}
if (body.firstName) {
body.firstName = capitalize(body.firstName);
}
if (body.lastName) {
body.lastName = capitalize(body.lastName);
}
// Checking and formatting email
if (body.email) {
body.email = body.email.toLowerCase();
body.email = body.email.trim();
// Checking for email in database
User.find({ email: body.email }, (err, EmailsFound) => {
if (EmailsFound.length > 0) {
var EmailsFoundErr = {
success: false,
message: "There is already an account with that email address"
};
hasErrors.errors = { ...hasErrors.errors, ...EmailsFoundErr };
}
});
}
// Getting User Session Token
UserSession.findById(updateUserInfo.sessionToken, function(err, userData) {
// Finding User ID using the current users session token
if (userData.isDeleted) {
var userDeletedError = {
success: false,
message:
"Your account is currently logged out, you must login to change account details"
};
hasErrors.errors = { ...hasErrors.errors, ...userDeletedError };
} else {
// Finding the user profile and updating fields that are present
User.findByIdAndUpdate(
userData.userId,
updateUserInfo.userInfo,
function(err, userInfo) {
// userInfo varable contains user db entry
if (err) {
var updateUserError = {
success: false,
message: "Error: Server Error"
};
hasErrors.errors = {
...hasErrors.errors,
...updateUserError
};
}
if (isEmpty(hasErrors.errors)) {
res.send({
success: true,
message: "Success: You have updated your profile!"
});
} else {
res.send({
success: false,
message: hasErrors.errors
});
}
}
);
}
});
});
I am trying to use the node.js Google API to iterate over my email messages
const google = require('googleapis');
The problem is that I keep getting the same email messages and every response contains the exact same nextPageToken.
I also noticed that trying to control the maxResults parameter has no effect. I tried to add them to the options object and the query objects and it had no effect in either way.
function listThreads(auth, nextPageToken) {
const gmail = google.gmail('v1');
const query = {
auth : auth,
userId: 'me',
q: ""
};
const options = {maxResults: 20}
if (nextPageToken) {
query.pageToken = nextPageToken;
}
gmail.users.messages.list(query, options, function(err, response) {
if (err) {
console.log('The API returned an error: ' + err);
return;
}
const messages = response.messages;
if (messages.length === 0) {
console.log('No threads found.');
} else {
for (let i = 0; i < messages.length; i++) {
const message = messages[i];
gmail.users.messages.get({
auth : auth,
userId: 'me',
id : message.id
}, function(err, response) {
if (err) {
logger.error("Failed to get email", err);
} else {
const parser = new Parser();
parser.parse(response.payload, response.labelIds);
}
});
}
}
if (response.nextPageToken) {
listThreads(auth, response.nextPageToken);
}
});
}
What am I doing wrong?