Category: JavaScript

Sometimes, we want to fix the req.user undefined error with Node.js, Express, and Passport.

In this article, we’ll look at how to fix the req.user undefined error with Node.js, Express, and Passport.

How to fix the req.user undefined error with Node.js, Express, and Passport?

To fix the req.user undefined error with Node.js, Express, and Passport, we should make sure Passport session state is set up in our app.

For instance, we should write

app.use(session({
  secret: 'anything'
}));
app.use(passport.initialize());
app.use(passport.session());

to call session to enable session storage with session.

Then we call passport.initialize to initialize Passport.

And then we call passport.session to let Passport handle sessions in our Express app.

Then when a user is logged in, req.user should be set.

Conclusion

To fix the req.user undefined error with Node.js, Express, and Passport, we should make sure Passport session state is set up in our app.

Sometimes, we want to create an empty file in Node.js.

In this article, we’ll look at how to create an empty file in Node.js.

How to create an empty file in Node.js?

To create an empty file in Node.js, we can call the fs.openSync method.

For instance, we write

fs.closeSync(fs.openSync(filePath, 'w'));

to call fs.openSync with the filePath of the file to write to and the 'w' (write) permission.

Then we close the returned file handle with fs.closeSync.

Conclusion

To create an empty file in Node.js, we can call the fs.openSync method.

Sometimes, we want to check if a variable exists with the Node.js Jade template engine.

In this article, we’ll look at how to check if a variable exists with the Node.js Jade template engine.

How to check if a variable exists with the Node.js Jade template engine?

To check if a variable exists with the Node.js Jade template engine, we can check if the property name with the variable name exists in the locals object.

For instance, we write

if locals.username
  p= username
else
  p No Username!

to check if the username template variable exists with if locals.username.

Conclusion

To check if a variable exists with the Node.js Jade template engine, we can check if the property name with the variable name exists in the locals object.

Sometimes, we want to upload a file using POST request in Node.js.

In this article, we’ll look at how to upload a file using POST request in Node.js.

How to upload a file using POST request in Node.js?

To upload a file using POST request in Node.js, we can submit our files in a form data object.

For instance, we write

const req = request.post(url, (err, resp, body) => {
  if (err) {
    console.log('Error!');
  } else {
    console.log('URL: ' + body);
  }
});

const form = req.form();
form.append('file', '<FILE_DATA>', {
  filename: 'myfile.txt',
  contentType: 'text/plain'
});

to call request.post with to make a POST request object req.

Then we call req.form to create a form form data object.

Then we call form.append with the name of the file input, the file data, and the file metadata respectively.

We get the response from body in the request.post callback.

Conclusion

To upload a file using POST request in Node.js, we can submit our files in a form data object.

Sometimes, we want to create global variables accessible in all views using Express and Node.js.

In this article, we’ll look at how to create global variables accessible in all views using Express and Node.js.

How to create global variables accessible in all views using Express and Node.js?

To create global variables accessible in all views using Express and Node.js, we can set the app.locals property.

For instance, we write

app.locals.baseUrl = "http://www.example.com"

to set app.locals.baseUrl to a string.

Then we can access the baseUrl string with

req.app.locals.baseUrl

in our middleware functions.

Conclusion

To create global variables accessible in all views using Express and Node.js, we can set the app.locals property.