nest-jayson

Nest.js implementation of JSON-RPC 2.0 built on top of jayson

Installation

$ npm install nest-jayson

Requirements

• Nest.js with express.js

Usage

Module

Register JsonRpcModule in app.module.ts

@Module({
    imports: [
        JsonRpcModule.forRoot({
            middlewares: [],
        }),
    ],
})
export class AppModule {}

Controller

Create a controller with @JsonRpcController decorator

@JsonRpcController('vaccination')
export class VaccinationController {
}

Method

Create a method with @JsonRpcMethod decorator, express Request object can be acquired by using @Req decorator, and JSON-RPC params object can be accessed with @Body decorator.

@JsonRpcController('vaccination')
export class VaccinationController {
    @JsonRpcMethod('getVaccination')
    getVaccination(@Body request: any, @Req req: Request);
}

Method Invocation

Invoke the registered method by calling controller.methodName with the JSON-RPC params object as the argument.

{
    "jsonrpc": "2.0",
    "method": "vaccination.getVaccination",
    "params": {
        "secureNo": "76481"
    },
    "id": "2"
}

Middleware

Middleware is a nestjs provider that implements the JsonRpcMiddleware interface, middleware can intercept the request before it reaches the controller method. Use callback method to return the response immediately, or call next method to pass the request. As middlewares are nestjs provider, it can be injected with other providers.

import { JSONRPCCallbackType, JSONRPCResultLike } from 'jayson';
import { Request } from 'express';
import { JsonRpcMiddleware, JsonRpcMiddlewareInterface } from 'nestjs-jayson';

@JsonRpcMiddleware()
export class CacheMiddleware implements JsonRpcMiddlewareInterface {
  async use(
    req: Request,
    callback: JSONRPCCallbackType,
    next: (err: any) => void
  ): Promise<void> {
    const result = this.cache.get();
    if (result) {
      callback(null, result as JSONRPCResultLike);
    } else next(null);
  }
}

Registering Middleware

Register the middleware in the JsonRpcModule.forRoot method by providing method filters and the middleware provider. Use *.* to match all methods in all controllers, or controllerName.* to match all methods in a specific controller. Even *.methodName can be used to match a specific method in all controllers. Middlewares are applied in order of registration.

@Module({
    imports: [
        JsonRpcModule.forRoot({
            middlewares: [
                {
                    methods: ['*.*'],
                    middleware: AuthMiddleware,
                },
            ],
        }),
    ],
})

Error Handling

nestjs-jayson provides error handling capabilities in order to provide proper JSON-RPC error response.

License

Distributed under the MIT License

Acknowledgements

https://www.npmjs.com/package/jayson