cmd-try-catch description

This repository enables the ability to provide an array of commands with catch alternatives

The reason for this library

• I want to supply an array of commands that run in sequence, one after the other.
• If one of those commands fail then I want to try a series of catch commands.
• If the catch command fails, then move onto the next catch command. If that catch command succeeds then retry the original command.
• If the original command passes, then move onto the next top command, otherwise stop the entire sequence.
• If the original command fails again, then try any remaining untried catch commands. If there are no more catch commands, then stop the sequence.
• If all commands in the top list pass then return a success response.

Working example

package.json

{
  "name": "interact-cmd-try-catch",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node index.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "cmd-try-catch": "^2.0.0",
    "got": "^11.7.0"
  }
}

index.js

const util = require('util');
const sync = require('cmd-try-catch').default;
const got = require('got');

const urlExistPromise = url =>
  new Promise (async (resolve, reject) => {
    await got(url).then(() => {
      resolve({
        success: url
      });
    }).catch(() => {
      reject({
        error: Error(`url: "${url}" does not exist`)
      })
    })
  });

const init = async () => {
  const objReturn = await sync([
    {
      func: async () => await urlExistPromise('http://localhost/tutorial'),
      catch: [{
        troubleshoot: /url\:\s\"http\:\/\/localhost\/tutorial\"\sdoes\snot\sexist/,
        cmd: `docker run -d -p 80:80 --name mydocker docker/getting-started`
      }]
    }
  ]);
  console.log('objReturn= ', util.inspect(objReturn, true, 4));
}

init();

outputs

npm run start

> [email protected] start c:\node_all\interact-cmd-try-catch
> node index.js


1: func

CATCH: docker run -d -p 80:80 --name mydocker docker/getting-started

1: func
objReturn=  {
  map: [
    {
      func: [AsyncFunction: func] {
        [length]: 0,
        [name]: 'func',
        [Symbol(Symbol.toStringTag)]: 'AsyncFunction'
      },
      catch: [
        {
          troubleshoot: /url\:\s\"http\:\/\/localhost\/tutorial\"\sdoes\snot\sexist/,
          cmd: 'docker run -d -p 80:80 --name mydocker docker/getting-started',
          complete: [Object]
        },
        [length]: 1
      ],
      complete: { success: 'http://localhost/tutorial' }
    },
    [length]: 1
  ],
  isComplete: true
}

Providing a series of commands

example:

import sync, {stripMap} from 'sync';

const objResult = sync([{
  // 1 try command1Try, 5 try again
  cmd: 'command1Try',
  catch: [{
     // 2 commandTry1 fails so try this
    cmd: 'command1Catch1'
  }, {
    // 3 command1Catch1 fails so try this
    cmd: 'command1Catch2'
  }, {
     // 4 command1Catch2 fails so try this
    cmd: 'echo catchSuccess' // This succeeds so retry command1Try.
  }, {
     // 6 command1Try fails so try this
    cmd: 'another error'
  },
   // 7 no more catch commands to try, so end sequence
  ]
}, {
  // Doesn't reach here because command1Try has failed and there are no catches for it.
  cmd: 'echo success'
}]);

const isAllPass = objResult.isComplete;

const getMapOfPasses = stripMap(objResult.map)
/*
getMapOfPasses = [
  {
    complete: false,
    catch: [{
      complete: false
    }, {
      complete: false
    }, {
      complete: true
    }, {
      complete: false
    }],
  },
  {
    complete: null
  }
];
*/

You can supply either a cmd, function or promise - as long as they all return an objectSuccessOrError

as success

import {IObjSuccessOrError} from 'sync';
const objSuccessOrError: IObjSuccessOrError = {
  success: 'some message string'
}

as error

import {IObjSuccessOrError} from 'sync';
objSuccessOrError: IObjSuccessOrError  = {
  error: Error('some error')
}

example with func and promise

import sync, { TFunc } from 'cmd-try-catch';

const funcPromiseError: TFunc = () => new Promise((resolve, reject => {
  reject({
    error: Error('custom error')
  });
}));

const funcPromiseSuccess: TFunc = () => new Promise((resolve, reject => {
  resolve({
    success: 'some message'
  });
}));

const funcError: TFunc = () => ({
  error: Error('custom error')
});

const funcSuccess: TFunc = () => ({
  success: 'some message'
});


const objResult = sync([{
  cmd: 'command1Try',
  catch: [{
    func: funcError,
  }, {
    func: funcPromiseError,
  }, {
    func: funcPromiseSuccess,
  }]
}, {
  func: funcSuccess
}]);

Real world usecase

The real benefit of this is usecases with something like docker, sql, bash scripts etc...

example usecase

import { v4 as uuidv4 } from 'uuid';
import {exec} from 'child_process';
import urlExist from 'url-exist';

import { ISyncReturn , TFunc, TPromiseResponse } from 'src/types';
import sync from 'src/sync';


type TUrlExistPromise = (url: string) => TPromiseResponse;
const urlExistPromise: TUrlExistPromise = async url =>
  await new Promise (async (resolve, reject) => {
    const exist: boolean = await urlExist(url);
    if (exist) {
      resolve({
        success:  url
      });
    } else {
      reject({
        error: Error(`does not exist -${url}`)
      })
    }
  });


let objReturn: ISyncReturn;
const getUrlDockerTutorial: TFunc = async () => await urlExistPromise('http://localhost/tutorial');

let id: string = uuidv4();
describe('sync - usecase', () => {
  describe('Test if docker tutorial is running in localhost. Otherwise catch and run docker getting started, then retest', () => {
    beforeAll(async () => {
      objReturn = await sync([
        {
          func: getUrlDockerTutorial, // 1 first try fails, 3 second try passes
          catch: [{
            cmd: `docker run -d -p 80:80 --name ${id} docker/getting-started` // 2 run docker, now retry first command
          }]
        }
      ]);
    });
    afterAll(async () => {
      await exec(`docker stop ${id}`);
      await exec(`docker rm ${id}`);
    })
    it('should complete', () => {
      expect(objReturn.isComplete).toBe(true);
    });
  });
});

Licence

This particular npm package I have provided MIT licence but please note that the dependencies of this package are variable. Some are Apache-2.0, BSD, BSD-2-Clause, BSD-3-Clause, BSD*, CC-BY-3.0, CC-BY-4.0, CC0-1.0, ISC, GPL, LGPL-3.0, MIT, WTFPL, UNLICENCED and so forth. They may change. Please be aware if using this under any commercial practice that it may break some of those licences and you hold your own liability.

This package uses those licences to provide working solution example. Please contact me if you wish to contract me and I maybe able to minimize this project to reduce any liability of those dependent licences.

Enjoy