如何防止Service running ...消息首先被记录?我想要testDBConnection fn中的消息。而是先登录。当数据库未运行时,我希望保持记录Looks like DB is not running消息,并且一旦数据库启动DB connection has been established,并且Service running ...消息就会跟随。我尝试了多种方法,但是无法提供正确的代码。谢谢你的帮助。

index.js

import app from './config/express';
import config from './config/config';
import logger from './config/winston';
import { initDbConnection } from './server/db';

app.listen(config.port, () => {
  initDbConnection();
  logger.info(`Service running and listening on port ${config.port}`);
});


db.js

import knex from 'knex';
import config from '../config/config';
import logger from '../config/winston';

const { db } = config;
let pool;

const testDBConnection = (client) => {
  const intervalId = setInterval(async () => {
    try {
      await client.select(1);
      logger.info('DB connection has been established');
      clearInterval(intervalId);
    } catch (error) {
      logger.error('Looks like DB is not running');
    }
  }, 2000);
};

export const initDbConnection = (mock) => {
  if (mock) {
    pool = knex({});
  } else {
    pool = knex({
      client: 'pg',
      version: '7.4.2',
      connection: db,
      debug: true
    });
    testDBConnection(pool);
  }
};

export const getDb = () => pool;

最佳答案

您可以为此使用异步/等待。

import app from './config/express';
import config from './config/config';
import logger from './config/winston';
import { initDbConnection } from './server/db';

app.listen(config.port, async () => {
  await initDbConnection();
  logger.info(`Service running and listening on port ${config.port}`);
});


db.js:

import knex from 'knex';
import config from '../config/config';
import logger from '../config/winston';

const { db } = config;
let pool, connected;

const testDBConnection = (client) => {
   return new Promise(resolve => {
   const intervalId = setInterval(async () => {
        try {
          await client.select(1);
          if (connected) {
              return;
          }
          connected = true;

          logger.info('DB connection has been established');
          clearInterval(intervalId);
          resolve('success');
        } catch (error) {
          logger.error('Looks like DB is not running');
        }
      }, 2000);
   });
};

export const initDbConnection = (mock) => {
  if (mock) {
    pool = knex({});
  } else {
    pool = knex({
      client: 'pg',
      version: '7.4.2',
      connection: db,
      debug: true
    });
    return testDBConnection(pool);
  }
};

export const getDb = () => pool;


这样,只有在解决了initDbConnection之后,才会调用app.listen cb中的记录器。另一种方法是仅使用promise then

10-07 19:14
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