loopback-log-extension

log extension for LoopBack 4

Install npm i loopback-log-extension --save or yarn add loopback-log-extension

Overview

This repository shows you how to use @loopback/cli to write a complex logging extension that requires a Component, Decorator, and a Mixin.

To use this extension you can add the LogMixin to your Application which will provide you a function to set the Application wide log level as well as automatically load the LogComponent. Only Controller methods configured at or above the logLevel will be logged.

You may alternatively load LogComponent yourself and set the log level using the appropriate binding keys manually if you don't wish to use the LogMixin.

Possible levels are: DEBUG < INFO < WARN < ERROR < OFF

Possible levels are represented as numbers but users can use LOG_LEVEL.${level} to specify the value instead of using numbers.

A decorator enables you to set the log level for Controller methods, at or above which it should be logged.

Usage

1. Create datasource to save token

Sample:

datasources/token.datasource.config.json file

{
    "name": "token",
    "connector": "memory",
    "localStorage": "",
    "file": "../../data/token.json"
}

datasources/token.datasource.ts file

import {
  inject,
  lifeCycleObserver,
  LifeCycleObserver,
  ValueOrPromise,
} from '@loopback/core';
import { juggler } from '@loopback/repository';
import config from './token.datasource.config.json';
import * as path from 'path'

interface TokenDataSourceInterFace {
  name: string
  connector: string
  localStorage: string
  file: string
}

@lifeCycleObserver('datasource')
export class TokenDataSource extends juggler.DataSource
  implements LifeCycleObserver {
  static dataSourceName = 'token';

  constructor(
    @inject('datasources.config.token', { optional: true })
    dsConfig: TokenDataSourceInterFace = config,
  ) {
    const newPath = path.join(__dirname, dsConfig.file)
    dsConfig.file = newPath
    super(dsConfig);
  }

  /**
   * Start the datasource when application is started
   */
  start(): ValueOrPromise<void> {
    // Add your logic here to be invoked when the application is started
  }

  /**
   * Disconnect the datasource when application is stopped. This allows the
   * application to be shut down gracefully.
   */
  stop(): ValueOrPromise<void> {
    return super.disconnect();
  }
}

2. Create Token Repository

repositories/token.repository.ts file

import { DefaultCrudRepository } from '@loopback/repository';
import { Token, TokenRelations } from 'loopback-elog-extention';
import { TokenDataSource } from '../datasources';
import { inject } from '@loopback/core';

export class TokenRepository extends DefaultCrudRepository<
  Token,
  typeof Token.prototype.id,
  TokenRelations
  > {
  constructor(@inject('datasources.token') dataSource: TokenDataSource) {
    super(Token, dataSource);
  }
}

In application.ts file

import {LogMixin, LOG_BINDINGS} from 'loopback-log-extension';
import { TokenRepository } from './repositories';
// Other imports ...

class LogApp extends LogMixin(BootMixin(RestApplication)) {
  constructor(options?: ApplicationConfig) {
    super(options);

    this.projectRoot = __dirname;
    this.configure(LOG_BINDINGS.COMPONENT).to({
      enableElog: true
    })
    this.configure(LOG_BINDINGS.LOGGER).to({
      url: '${url_elog}',
      username: '${elog_username}',
      password: '${elog_password}',
      appCode: '${elog_appcode}',
      tokenRepo: TokenRepository
    })
  }
}

In controllers/my.controller.ts file

...

import {
  LOG_LEVEL,
  LOG_BINDINGS,
  ElogService,
  log
} from 'loopback-elog-extention';
class MyController {
  constructor(
    @inject(LOG_BINDINGS.LOGGER)
    private logger: ElogService
  ) { }

  @log({
    level: LOG_LEVEL.WARN,
    description: 'description for log',
    fn: {
      code: 'function code',
      name: 'function name'
    },
    // function parse request param for save to log
    parseInfo: () => {},
    // function parse result of method to get status of request and result code
    parseResult: result => { //result of method
      return {
        status: result.status,
        resultCode: result.responseCode
      }
    }
  })
  @get('/')
  hello() {
    ...
    this.logger.addTimeLine('test,', true, 'abc.txt', 'abc')
    ...
    return {
      status: true,
      resultCode: 'I001'
    };
  }
}

In sequence.ts file

...

import { LOG_BINDINGS, LogFn } from './loopback-elog-extention'
export class MySequence implements SequenceHandler {
  constructor(
    ...
    @inject(LOG_BINDINGS.LOG_ACTION)
    protected log: LogFn
  ) { }

  async handle(context: RequestContext) {
    try {
      const { request, response } = context;
      const route = this.findRoute(request);

      const args = await this.parseParams(request, route);
      const result = await this.invoke(route, args);
      this.send(response, result);

      this.log(request, args[0], result, true)
    } catch (err) {
      this.reject(context, err);
      this.log(context.request, context.request.body, err, false)
    }
  }
}