When working with data, it is important to ensure that it has the correct structure.

Mongoose allows you to define simple validation rules in your schema.

const userSchema = new mongoose.Schema({
  name: {
    type: String,
    required: true
  },
  age: {
    type: Number
  }
});

Here, the name field is required. If it is missing, Mongoose will not allow the document to be saved.

app.post('/users', async (req, res) => {
  try {
    const user = new User(req.body);
    const savedUser = await user.save();

    res.json(savedUser);
  } catch (error) {
    res.status(400).send('validation error');
  }
});

Validation helps prevent invalid or incomplete data from being stored in the database.