13 Building a Backend with Node.js and Swagger Codegen

José’s PetSitter team has created an OpenAPI definition for the API that connects the frontend with the backend. They have now reached the stage of the project where both developers are confident that the API is solid enough to start working on the implementation. In this chapter, we’ll join Nidhi, the backend developer, as she builds a backend that exposes the API that Max designed in chapter 10 and that she herself reviewed in chapter 11. While we’ll touch upon backend functionality like database persistence, our primary focus will be the process of going from API to code.

Our chosen backend technology is Node.js. Node.js is the server-side version of JavaScript. Of course there are a lot of other programming languages to choose from, such as Python, Ruby, Go (which we used for the FarmStall API in part 1), or PHP. We picked JavaScript because we expect most developers to have at least a basic grasp of the language syntax, even if it’s just from the client-side.

13.1 The problem

13.2 Introducing Swagger Codegen

13.2.1 Client code generation

13.2.2 Server code generation

13.2.3 Swagger Generator

13.3 The backend architecture

13.3.1 Generating the backend

13.3.2 Investigating the architecture

13.3.3 OpenAPI changes

13.4 Updating OpenAPI for the backend

13.4.1 Adding operation IDs

13.4.2 Tagging API operations

13.4.3 Regenerating the backend stubs

13.5 Running and testing the backend

13.5.1 Testing with Postman

13.5.2 Testing input validation

13.5.3 Output validation with prism

13.6 Database persistence with Mongoose

13.6.1 Another API modification

13.6.2 Getting ready to use MongoDB

13.6.3 Configuring Mongoose in the project

13.6.4 Creating models

13.7 Implementing API methods