Added Atul user login express js

Express Js/OAtulA/UserAuth/Learnings with this project/URLS_testing.md

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+# My Route was not working :/
+
+Everything seemed ok.  
+But I got no output for this route
+
+<details>
+<summary> login route </summary>  
+
+```javascript
+// to check user login
+app.post('/users/login', async (req, res) => {
+    const user = users.find(user => req.body.name === user.name)
+    if (user === null) {
+        return res.status(401).send('Cannot find the user.')
+    }
+    console.log(user)
+    try {
+        if (bcrypt.compare(req.body.password, user.password)) {
+            res.status(200).send('success')
+            console.log('success')
+        }
+        else {
+            res.status(401).send('Not allowed')
+        }
+    }
+    catch {
+        res.status(500).send("Invalid user")
+    }
+})
+
+```
+
+</details>  
+
+<details>
+<summary>Also now corrected a simple mistake </summary>
+
+```javascript
+// to check user login
+app.post('/users/login', async (req, res) => {
+    const user = users.find(u => req.body.name ===u.name)
+    if (user === null) {
+        return res.status(401).send('Cannot find the user.')
+    }
+    console.log(user)
+    try {
+        if ( await bcrypt.compare(req.body.password, user.password)) {
+            res.status(200).send('success')            
+        }
+        else {
+            res.status(401).send('Not allowed')
+        }
+    }
+    catch {
+        res.status(500).send("Invalid user")
+    } 
+})
+```
+
+</details>
+
+- I identified my mistakes
+  - I forgot to write the await before the bcyrpt.compare
+  - I wrote  
+    ```const user = users.find(user => req.body.name === user.name)```  
+        INSTEAD OF  
+    ```const user = users.find(u => req.body.name ===u.name)```  
+
+I asked Perplexity.ai there was no error.  
+Then I told it about my fetch request.
+which looked like this.
+
+```javascript
+const options = {
+    method: 'POST',
+    headers: {'Content-Type': 'application/json'},
+    body: '{"name": "Kunarl", "password": "fksdfh34234,wrw"}'
+  };
+
+  fetch(`localhost:$(PORT)/users/login`, options)
+    .then(response => console.log(response))
+    .catch(err => console.error(err));
+```
+
+It said I should try putting <http://localhost:$(PORT)/users/login>  
+This worked and I am feeling good and silly

Express Js/OAtulA/UserAuth/Learnings with this project/bodyParser.md

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+# I learnt about the bodyparser the hard way
+
+## What exactly happened?  
+
+I was trying to get some data from requests.  
+It didn't work.
+
+<details>
+
+ <summary> <b>server.js</b> </summary>
+
+```javascript
+const express = require("express")
+const app = express()
+const bcrypt = require("bcrypt")
+
+const users = [{ name: "Demo", password: "wohoa235#21" }]
+// This is just for the basic project.
+//In real use case we will get from the server db sql/no sql
+
+app.listen(8002, () => {
+    console.log("Server started\n Listening on http://localhost:8002")
+})
+
+// also we will add middleware route to check if user making the request
+// has the permission to post or get on this route.
+app.post('/users', async (req, res) => {
+    try {
+        const salt = await bcrypt.genSalt()
+        debugger
+        console.log(req.body)
+        console.log(req.body.name," : ", req.body.password)
+        const hashedPassword = await bcrypt.hash(req.body.password, salt)
+        const user = { name: req.body.name, password: hashedPassword };
+        users.push(user);
+        res.status(201).send(user);
+        console.log("Newly added user: ",users[users.length-1])
+    }
+    catch(err){
+        console.log(err.message);
+        res.status(500).send()
+    }
+})
+
+app.get("/", (req, res) => {
+    res.send("Yeah connected");
+})
+
+app.get('/users', (req, res) => {
+    res.json(users);
+})
+
+app.get("/:page", (req, res) => {
+    res.send(`We are working on ${req.params.page}`)
+})
+```
+
+</details>
+
+## Missing piece
+
+I needed body-parser.  
+But I thought let's just do it using express.json() .  
+Since I am using express anyways.  
+
+so I used express.json()

Express Js/OAtulA/UserAuth/Learnings with this project/know_which_method_is_async.txt

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+Again I know figured it out looking objectively.
+That bcrypt.compare is async so now I put the await and it works well.

Express Js/OAtulA/UserAuth/README.md

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+# UserAuth
+
+## About
+
+So this is a basic user authentication express.js app.  
+
+You can  
+- POST /signup register user to route 
+- PUT /users/password to update password
+- PUT /users/name to update name
+- DELETE /users/remove to delete a user 
+- POST /users/login to login user
+- GET /users to see all users
+
+You can look at Thoughts/req_body.txt to see the content template for the requests.
+
+You can try and run Request tests/post-user2.js to check the routes.
+
+I have used this 
+
+```
+"scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "dev": "node --watch server.js"
+  },
+```
+
+So the ```node --watch``` is available only for version >= Node.js 18.11.0  
+The --watch flag was added to Node.js in version 18.11.0
+
+You might want to use nodemon installed as global to check this out.

Express Js/OAtulA/UserAuth/Request tests/Bunch-of-users.txt

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+Mehul fsdlfh2324
+Piyush 23423hsdkjfhsdk
+Kunarl fksdfh34234,wrw
+Kishauma fsdhf421*7
+Nourami sdfh3,87

Express Js/OAtulA/UserAuth/Request tests/Login.js

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+const options = {
+    method: 'POST',
+    headers: {'Content-Type': 'application/json'},
+    body: '{"name": "Kunarl", "password": "fksdfh34234,wrw"}'
+  };
+
+  fetch('http://localhost:8002/users/login', options)
+    .then(response => console.log(response))
+    .catch(err => console.error(err));

Express Js/OAtulA/UserAuth/Request tests/post-user2.js

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+const fs = require('fs')
+let format_user=[];
+fs.readFile('Bunch-of-users.txt', 'utf8', (err, data) => {
+  if (err) {
+    console.error(err);
+    return;
+  }
+  users = data;
+  newUsers = users.split('\n')
+  console.log('newUsers= ', newUsers)
+  format_user = newUsers.map(user => {
+    user2 = user.split(' ');
+    new_user = { name: user2[0], password: user2[1] };
+    return new_user;
+  });
+
+  console.log('format_user=',format_user)
+  console.log(format_user.length)
+  for(let i=0; i< format_user.length; i++ )
+  { let user = format_user[i];
+  fetch('http://localhost:8002/signup', {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json'
+    },
+    body: JSON.stringify({
+      name: user.name,
+      password: user.password
+    })
+  })
+    .then(response => {
+      if (response.ok) {
+        return response.json();
+      } else {
+        throw new Error('Error creating user');
+      }
+    })
+    .then(data => {
+      console.log('New user created:', data);
+    })
+    .catch(error => {
+      console.error('Error:', error);
+    });
+}
+});
+// console.log(format_user.length)
+// format_user.forEach(user => 
+for(let i=0; i< format_user.length; i++ )
+  { let user = format_user[i];
+  fetch('http://localhost:8002/users', {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json'
+    },
+    body: JSON.stringify({
+      name: user.name,
+      password: user.password
+    })
+  })
+    .then(response => {
+      if (response.ok) {
+        return response.json();
+      } else {
+        throw new Error('Error creating user');
+      }
+    })
+    .then(data => {
+      console.log('New user created:', data);
+    })
+    .catch(error => {
+      console.error('Error:', error);
+    });
+}

Express Js/OAtulA/UserAuth/Thoughts/req_body.txt

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+For the normal requests the body will look like this.
+`
+body: JSON.stringify({
+      name: 'Aman',
+      password: '1245heail'
+    }
+`
+But for the put I want request
+for password update
+`
+body:JSON.stringify({
+	existingUser:{
+      name: 'Aman',
+      password: '1245heail'
+    },
+    Update:{
+    password: 'mohan2984'
+	}
+}
+`

Express Js/OAtulA/UserAuth/USERS.json

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+[{"name":"Demo","password":"wohoa235#21"},{"name":"Jagrit","password":"gosohds23qafhwe3.werw"},{"name":"Kushsa","password":"$2b$10$wU4rp1X6et/.SdV/CUvBve4O0zxL9Lbrci6Zr8.V94LUzFKnfBBb2"},{"name":"Mehul","password":"$2b$10$0CepIXQxYrOz1R8UMFe/4.CDPIkxjpL2l8GWciqOVpVqCknznmRLu"},{"name":"Kishauma","password":"$2b$10$NI1HLr1PZAhtY0kUNlFdle56hJ5ueslW4tuj1f1PN8yT0ZZiwlZ5i"},{"name":"Piyush","password":"$2b$10$dcuh7eMyKvXsvFyouLriq.6vmN2YA0/8GaET7fqeY6BNn0b24DCnK"},{"name":"Kunarl","password":"$2b$10$gnQVjfEXv1et7w20QAVla.NupHyy24AewUy6rjtUoQn3eVXRxOiN."},{"name":"Nourami","password":"$2b$10$Jz47Bg8LFPlviMwlRifSb.YXi7K3U8ja45evZDUKGmoJn0R7HltcS"}]