CODEWITHSUNDEEP
node.jsexpress
UmaiZ
UmaiZ

Reputation: 133

Node express find data in filter

I am following some tutorial but there is some problem in finding value in array . This is how my code looks 

const express = require('express');
const app = express();

const courses = [
  {id: '1', name: 'ITCS1'},
  {id: '2', name: 'ITCS2'},
  {id: '3', name: 'ITCS3'},
];

app.get('/api/courses/:id', (req, res) => {
  const course = courses.find(c => c.id === parseInt(req.params.id));
  if (!course) res.status(404).send('Course not found for given id');
});

const port = process.env.PORT || 3000;
app.listen(port, () => console.log(`Listening on port ${port}`));

when i am loading this url http://localhost:5000/api/courses/1 its giving me course not found for given id

But the expected result is {id: '1', name: 'ITCS1'} Because id 1 is in courses array. So why he is showing error because id is matching with array ?

Upvotes: 0

Views: 2128

Answers (6)

Titus Sutio Fanpula
Titus Sutio Fanpula

Reputation: 3613

It's work with this code:


const express = require('express');
const app = express();

const courses = [
  {id: '1', name: 'ITCS1'},
  {id: '2', name: 'ITCS2'},
  {id: '3', name: 'ITCS3'},
];

app.get('/api/courses/:id', (req, res) => {
  const course = courses.find(c => c.id === req.params.id);
  if (!course) res.status(404).send('Course not found for given id');
});

const port = process.env.PORT || 3000;
app.listen(port, () => console.log(`Listening on port ${port}`));

The reason why you get an error, because you're using parseInt.

And in your course, your id is a string, not integer. So, you should not to use parseInt.

If you want to using parseInt, please update your course array, an make your id is an integer, not a string.

An example:

const courses = [
  {id: 1, name: 'ITCS1'},
  {id: 2, name: 'ITCS2'},
  {id: 3, name: 'ITCS3'},
];

Now, you can use parseInt(req.params.id) and it's will working fine.

I Hope it's can help you.

Upvotes: 1

Karma Blackshaw
Karma Blackshaw

Reputation: 942

It's because you're using strict equal and you courses has it's id as a string.

You can either change your courses object to:

const courses = [
  {id: 1, name: 'ITCS1'},
  {id: 2, name: 'ITCS2'},
  {id: 3, name: 'ITCS3'},
];

or use double equal:

const course = courses.find(c => c.id == req.params.id);

or parse both: 

const course = courses.find(c => parseInt(c.id) === parseInt(req.params.id))

But I suggest changing the data type of courses.id and using the strict equal. But that's only in my opinion. You can learn more about strict and loose equality here

Upvotes: 0

oebilgen
oebilgen

Reputation: 41

That's because c.id is a string but you are converting the id parameter to int with parseInt(req.params.id). '1'===1 is false. Use this:

app.get('/api/courses/:id', (req, res) => {
  const course = courses.find(c => c.id === req.params.id);
  if (!course) res.status(404).send('Course not found for given id');
});

=== operator returns true only if the operands have the same value and type. Using == operator would work in your case but it's not recommended as it may lead false positives.

Upvotes: 0

Richard Lovell
Richard Lovell

Reputation: 888

This is because you’re comparing a string and integer strictly. You could either use two equal signs or change the data types to match.

Upvotes: 0

Fahad Hassan
Fahad Hassan

Reputation: 811

You have type string of id field. And you are matching it with int type field. Make both field types either make both of them int or stirng.

courses.find(c => c.id === req.params.id.toString())

Or 

courses.find(c => parseInt(c.id) === parseInt(req.params.id))

Upvotes: 0

Orkhan Alikhanov
Orkhan Alikhanov

Reputation: 10060

Apply parseInt for both sides

courses.find(c => parseInt(c.id) === parseInt(req.params.id))

or use == not ===

courses.find(c => c.id == req.params.id)

Upvotes: 0

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