> For the complete documentation index, see [llms.txt](https://hemantajax-2.gitbook.io/mongoose-step-by-step/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hemantajax-2.gitbook.io/mongoose-step-by-step/mongoose-crud.md).

# Mongoose CRUD

## CRUD Setup

```javascript
// grab the user model
var User = require('./app/models/user');

// create a new user
var newUser = User({
  name: 'Hemant',
  age: 30
});
```

### Create  create a new user

```javascript
// save the user
newUser.save(function(err) {
  if (err) throw err;

  console.log('User created!');
});
```

## Read

* one specific user
* all users
* similar users

### Find All  get all the users

```javascript
// Model.find(conditions, [fields], [options], [callback])

User.find({}, function(err, users) {
  if (err) throw err;

  console.log(users);
});

// No callback... 
// Deferred execution 
var query = User.find();

// With callback... Executes query immediately 
User.find(function (err, results) { 
    // handle the error... Or results here
});  

// With callback and query conditions 
User.find({ memberName: 'Hemant' }, function (err, results) { 
    // handle the error... Or results here 
}); 

// Limit the returned fields... 
User.find({ memberName: 'Hemant' }, 'name, age', function (err, results) { 
    // handle the error... Or results here 
});

// Limit the returned fields with option
// Options examples... skip, limit, sort
User.find({ memberName: 'Hemant' }, 'name, age', { limit: 10 }, function (err, results) { 
    // handle the error... Or results here 
});
```

### Find One

```javascript
// No callback... No conditions... 
var query = User.findOne(); 
query.exec(function (err, results) { 
    // handle the error... Or results here 
}); 

// With conditions... 
var query = User.findOne({ memberName: ‘Mark’}); 

// With condition, no field filtering, and options... 
var query = User.findOne({ memberName: 'Hemant'}, null, { limit: 10 });
```

### Find By ID

```javascript
// get a user with ID of 1
User.findById(1, function(err, user) {
  if (err) throw err;

  console.log(user);
});
```

### Querying

```javascript
// get the date 1 month ago
var monthAgo = new Date();
monthAgo.setMonth(monthAgo.getMonth() - 1);

User.find({ admin: true }).where('created_at').gt(monthAgo).exec(function(err, users) {
  if (err) throw err;

  // show the admins in the past month
  console.log(users);
});


// Model.where(path, [val]) 
Customer.find({ discount: {$gte: 10, $lt: 20}, function(err, results) { 
    if (err) throw err; 
    console.log(results); 
});

Customer.where(‘discount’).gte(10).lt(20).exec(function(err, results) { 
    if (err) throw err; 
    console.log(results); 
});

// Chain where methods together... 
Customer.where(‘discount’).gte(10).lt(20) 
    .where(‘zipCode’, ‘12345’) 
    .exec(function(err, results) { 
        if (err) throw err; 
        console.log(results); 
    });
```

#### Querying Operator

```
$gt greater than 
$gte greater than or equal to 
$in exists in 
$lt less than 
$lte less than or equal to 
$ne not equal to 
$nin does not exist
```

## Update

```javascript
// Model.update(conditions, update, [options], [callback])

// Example: update multiple documents that match condition 
var condition = { firstName: ‘Bob’ }; 
var update = { firstName: ‘Robert’ }; 
Customer.update(condition, update, { multi: true }, function(err, numberAffected, raw) { 
    // Handle error, returned # affected, and raw response from MongoDB... 
});
```

### Get a User, Then Update

```javascript
User.findById(1, function(err, user) {
  if (err) throw err;

  user.location = 'uk';

  user.save(function(err) {
    if (err) throw err;

    console.log('User successfully updated!');
  });
});
```

### Find and Update

```javascript
// find the user hemant
// update him to Varun
User.findOneAndUpdate({ username: 'hemant' }, { username: 'Varun' }, function(err, user) {
  if (err) throw err;

  console.log(user);
});
```

### Find By ID and Update

```javascript
// find the user with id 4
// update username to Hemant
User.findByIdAndUpdate(4, { username: 'Hemant' }, function(err, user) {
  if (err) throw err;

  console.log(user);
});
```

## Delete

### Get a User, Then Remove

```javascript
User.find({ username: 'hemant' }, function(err, user) {
  if (err) throw err;

  user.remove(function(err) {
    if (err) throw err;

    console.log('User successfully deleted!');
  });
});
```

### Find and Remove

```javascript
// find the user with id 4
User.findOneAndRemove({ username: 'hemant' }, function(err) {
  if (err) throw err;

  console.log('User deleted!');
});
```

### Find By ID and Remove

```javascript
// find the user with id 4
User.findByIdAndRemove(4, function(err) {
  if (err) throw err;

  console.log('User deleted!');
});
```