Validation

Within a LoopBack application, validation can be added in various places depending on the usage. Some types of validations come out-of-the-box in LoopBack, such as type validation in the REST layer, whereas some require additional configuration or code.

There are various types of validations such as:

• validation of input/output for method invocations
• validation of model instance properties, for example, age < 0
• validation of model collections, for example, uniqueness

Let's take a closer look at how validation can be added in the following layers:

• REST layer
• Controller, Repository and Service Layer
• ORM layer

The validation-app example application is used in the following documentation pages for demonstration. In the example, a CoffeeShop model is being used. It has the following properties.

Property name	Type	Description
shopId	string	ID of the coffee shop
city	string	City where the coffee shop is located
phoneNum	string	Phone number of the coffee shop
capacity	number	Capacity of the coffee shop