Validate Request Payload with a Custom Pipe
Explore how to build a custom pipe in NestJS to handle cross-field validation scenarios. Learn to validate multiple fields together, such as matching state and postcode, using the PipeTransform interface. Understand how to apply and test this validation within your API endpoints for reliable data integrity.
Cross-field validation and custom pipe
NestJS offers a robust set of built-in pipes for general data validation tasks, ensuring the integrity of our data. However, in specific scenarios like cross-field validation, we might need a custom pipe to meet our unique requirements. Cross-field validation involves applying rules that consider multiple fields within a request payload.
In this lesson, we’ll delve into creating a custom pipe to handle a cross-field validation scenario.
Custom pipe
In NestJS, a custom pipe is implemented as a class that adheres to the PipeTransform interface. To create one, we must implement this interface, which requires defining a single method called transform(). This method takes two arguments, which are given below:
value: This is the value to be transformed.metadata(optional): This is a ...