title: create user in db with oauth node.js
body: <p>I've set up express server, i'm using passport.js 
  i'm using a local strategy right now where i'm authenticating the user</p>
  
  <pre><code>passport.use(new Strategy({
      usernameField: 'email'
    }, (email, password, cb) =&gt; {
    db.get().collection('user').findOne({email: email}, (err, user) =&gt; {
      if (err) {
        return cb(err)
      }
      if (!user) {
        return cb(null, false)
      }
      if (!bcrypt.compareSync(password, user.password)) {
        return cb(null, false)
      }
      return cb(null, user)
    })
  }))
  </code></pre>
  
  <p>i'm creating user in the router like this:</p>
  
  <pre><code>router.post('/signup', (req, res) =&gt; {
    const user = poster.user(req.body)
    if(user){
      db.get().collection('user').insert(user)
      res.send('success')
    }else{
      res.send('error')
    }
    // res.send(req.body)
  })
  </code></pre>
  
  <p>my question is that how i can create a user with oauth? Or shall i even create a user in my db when i'm using oauth? I want users to be able to login with facebook, twitter and google. </p>