Accessing Fastify

Overview

EzBackend is a wrapper of fastify and typeorm

Hence, it is possible that you need to access the underlying fastify functionality for advanced purposes

Getting the fastify server instance

From EzApp (No Instance)

For every EzApp, fastify instance functions are exposed for your usage, for example:

const app = new EzBackend();
const base = new EzApp();

base.get('/', async (req, res) => {
  return { hello: 'world' };
});

app.addApp('base', base);

app.start();

This creates a route / which returns {hello:'world'} when a GET request is performed

info

The function is only registered in the postHandler lifecycle

However, this does not get us access to the state of the server, nor the encapsulated instance.

From handler lifecycle (No Fastify Instance)

However, we may want access to our encapsulated instance, for example when we have added a Repo in the tree

We can do this action within the setHandler lifecyle, by accessing instance.server

const app = new EzBackend();
const base = new EzApp();

app.setHandler('Create Repo', async (instance, opts) => {
  instance.repo = {
    getOne: () => {
      return 'This is a repo';
    },
  };
});

base.setHandler('Use Repo', async (instance, opts) => {
  instance.server.get('/', async (req, res) => {
    return { repo: instance.repo.getOne() };
  });
});

app.addApp('base', base);

app.start();

In this way, we have the access to the encapsulated context of the ancestors of the instance, whereas in the previous case we were unable to create routes based on the encapsulated state of the instance

However, instance.server does not contain information about the current state of the server, which means that although it emulates many of the FastifyInstance commands, it does not access to stateful commands, such as getSchemas() or .prefix

base.setHandler('Get Prefix', async (instance, opts) => {
  console.log(instance.server.prefix); //undefined
  console.log(instance.server.getSchemas()); //undefined
});

From registered plugin (With instance and Fastify Instance)

If you need access to the actual state of the server, then you have to register a plugin as shown below

const app = new EzBackend();
const base = new EzApp();

base.setHandler('Create Hello World', async (instance, opts) => {
  instance.server.register(async (server, opts) => {
    console.log(server.prefix); // base
    console.log(server.getSchemas()); // Error Response Schema
  });
});

app.addApp('base', base, { prefix: 'base' });

app.start();

Understanding Fastify in the lifecycle

EzBackend utilises fastify in the lifecycle like this:

lifecycle	action
postHandler (1)	Create fastify instance in instance._server
postHandler (2)	Recursively register fastify plugins

As a result, the methods from EzApp or the instance.server in handler lifecycle result do not run at the time of definition.

Instead, the calling of the functions is deferred to the postHandler lifecycle, which is why you are unable to access the server state.

However, when you use register, you are able to gain access to the server instance at the time it is called in the postHandler lifecycle, which means that it has access to the full encapsulated instance by fastify

warning

Technically, you can register your functions with instance.server.register,but by accessing instance._server directly you may lose access to EzApp encapsulation and possibly experience breaking changes in the future