Built-in Validators
Mongoose provides built-in validators for common checks like required fields, min/max values, and enums.
Example
const productSchema = new Schema({
name: {
type: String,
required: [true, 'Product name is required'],
minlength: [2, 'Name must be at least 2 characters'],
maxlength: [100, 'Name cannot exceed 100 characters']
},
price: {
type: Number,
required: true,
min: [0, 'Price cannot be negative']
},
category: {
type: String,
enum: {
values: ['Electronics', 'Clothing', 'Food'],
message: '{VALUE} is not a valid category'
}
},
sku: {
type: String,
unique: true,
match: [/^[A-Z]{3}-\d{4}$/, 'SKU must be format XXX-0000']
}
});Custom Validators
Create custom validation logic for complex business rules.
Example
const userSchema = new Schema({
email: {
type: String,
validate: {
validator: function(v) {
return /^[\w.-]+@[\w.-]+\.\w+$/.test(v);
},
message: props => `${props.value} is not a valid email`
}
},
password: {
type: String,
validate: {
validator: function(v) {
return v.length >= 8;
},
message: 'Password must be at least 8 characters'
}
}
});
// Middleware (hooks)
userSchema.pre('save', async function(next) {
if (this.isModified('password')) {
this.password = await bcrypt.hash(this.password, 10);
}
next();
});