How do you use JSON schema validation to improve your API design and documentation?

1 What is JSON schema?

JSON schema is a standard for describing the format and constraints of JSON data. It can be used to specify the type, format, properties, and dependencies of each element in a JSON object or array. JSON schema can also define custom validation rules and error messages for invalid data. JSON schema is written in JSON or YAML, and can be referenced by a URI or an ID.

2 Why use JSON schema validation?

JSON schema validation can offer several advantages for API development and consumption. It can improve the quality and consistency of data by enforcing rules and constraints on input and output. Additionally, it can simplify documentation and communication of data models by providing a single source of truth for the API schema. Furthermore, it can speed up the development and testing process by allowing code and mock data generation from the schema, as well as programmatic data validation. Finally, it can enhance the user experience and error handling by providing meaningful and actionable feedback for invalid data.

4 How to use JSON schema validation

Using JSON schema validation for your API can be beneficial depending on your needs and preferences. For example, you can use it as a middleware for your API server to validate request and response data. It can also send appropriate error messages and status codes. There are various libraries and frameworks that support this, such as Express, Fastify, Hapi, and Restify. Additionally, you can use it as a client-side library for your API consumer to validate data sent and received from your API, as well as handle errors and exceptions gracefully. There are various libraries and frameworks that support this, such as Ajv, JSON Schema Validator, and tv4. Lastly, you can use it as a code generator for your API to generate client-side and server-side code from your JSON schema. It can also be used for mock data and tests. There are various tools and platforms that support this, such as OpenAPI Generator, JSON Schema to TypeScript, and Postman.

5 How to document your JSON schema

Documenting your JSON schema is an important step for making your API easy to understand and use. There are various methods to document your JSON schema, such as using JSON schema annotations and keywords to add descriptions, examples, titles, and other metadata, as well as defining custom validation rules and error messages. Additionally, you can use JSON schema documentation generators to create human-readable and interactive documentation, or JSON schema documentation standards to follow best practices and conventions. There are various tools and platforms that support these methods, such as JSON Schema Docs, Docson, Redoc, OpenAPI Specification, JSON Hyper-Schema, and JSON API.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?