Mar 28, 09:33 AM
2022-04-01:
function tryMe({one, two, three}) { console.log(one, two,three) ; }
const tmp = { one: 1, two: 2, three: 3 } ;
tryMe(tmp) ;
=========================================
https://www.sitepoint.com/community/t/promises-feedback/384246/3
consider passing an JSON object for parms in the future:
function tester({param}) {
console.log(JSON.stringify(param));
}
tester({param: { ‘parmOne’: 123, ‘paramTwo’: “two”}}) ;
===========
REPLACE:
function desiredCar(eachCar) {
const make = eachCar.make;
const model = eachCar.model;
const hp = eachCar.hp;
// then do stuff with make, model, and hp
}
WITH:
function desiredCar({make, model, hp}) {
}
=======
— Mark Edwards
,
Dec 16, 11:36 AM
knex examples to replace sequelize.
first create knex user:
DROP USER IF EXISTS ‘knexUser’@‘localhost’ ;
CREATE USER ‘knexUser’@‘localhost’ IDENTIFIED BY ‘knexPassword’;
GRANT ALL ON `comptonTransAnlys`.* TO ‘knexUser’@‘localhost’
IDENTIFIED BY ‘knexPassword’ WITH MAX_QUERIES_PER_HOUR 0
MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 MAX_USER_CONNECTIONS 0 ;
GRANT ALL PRIVILEGES ON `comptonTransAnlys`.* TO ‘knexUser’@‘localhost’ ;
- mariadb —host=localhost —user=knexUser —password=knexPassword comptonTransAnlys ;
// https://zetcode.com/javascript/knex/
// mariadb —host=localhost —user=knexUser —password=knexPassword knexDb ;
const knexConnectOptions = {
client: ‘mysql’,
debug: true,
connection: {
host : ‘localhost’,
port : 3306,
user : ‘knexUser’,
password : ‘knexPassword’,
database : ‘knexDb’
}
};
const knex = require(‘knex’)(knexConnectOptions);
knex.raw(“SELECT VERSION”)
.then ( (version) => console.log((version))
)
.catch((err) => { console.log( err); throw err })
.finally(() => {
knex.destroy();
});
knex.schema
.createTable(‘cars’, (table) => {
table.increments(‘id’) ;
table.string(‘name’) ;
table.integer(‘price’) ;
})
.then(() => console.log(“table created”))
.catch((err) => { console.log(err); throw err })
.finally(() => {
knex.destroy();
process.exit();
});
const cars = [
{ name: ‘Audi’, price: 52642 },
{ name: ‘Mercedes’, price: 57127 },
{ name: ‘Skoda’, price: 9000 },
{ name: ‘Volvo’, price: 29000 },
{ name: ‘Bentley’, price: 350000 },
{ name: ‘Citroen’, price: 21000 },
{ name: ‘Hummer’, price: 41400 },
{ name: ‘Volkswagen’, price: 21600 },
]
knex.from(‘cars’) // or just knex(‘cars’)
.insert(cars)
.then((id) => console.log(“data inserted: “ + id ) /* note display of returned ID! */
.catch((err) => { console.log(err); throw err })
.finally(() => {
knex.destroy();
process.exit();
});
knex.from(‘cars’) // or just knex(‘cars’)
.select(“*”)
.where (true) // optional!
.then((rows) => {
for (row of rows) {
console.log(`${row[‘id’]} ${row[‘name’]} ${row[‘price’]}`);
}
}).catch((err) => { console.log( err); throw err })
.finally(() => {
knex.destroy();
process.exit();
});
knex.from(‘cars’) // or just knex(‘cars’)
.select(“name”, “price”).where(‘price’, ‘>’, ‘50000’)
.where (true)
.then((rows) => {
for (row of rows) {
console.log(`${row[‘name’]} ${row[‘price’]}`);
}
})
.catch((err) => { console.log( err); throw err })
.finally(() => {
knex.destroy();
process.exit();
});
// mariadb —host=localhost —user=knexUser —password=knexPassword knexDb ;
const knexConnectOptions = {
client: ‘mysql’,
debug: true,
connection: ‘mysql://knexUser:knexPassword@localhost:3306/knexDb’
};
const knex = require(‘knex’)(knexConnectOptions);
knex(‘cars’)
.where ({‘id’: 6 }) // OR .where (‘id’ , ‘=’, 6)
.update({ name : ‘Toyota’}) /* notice {} */
.catch((err) => { console.log( err); throw err })
.finally(() => {
knex.destroy();
process.exit();
});
// delete!
knex(‘cars’)
.where (‘id’ , ‘=’, 6)
.del()
.catch((err) => { console.log( err); throw err })
.finally(() => {
knex.destroy();
process.exit();
});
// short connection string:
const knexConnectOptions = {
client: ‘mysql’,
connection: ‘mysql://knexUser:knexPassword@localhost:3306/knexDb’
};
const knex = require(‘knex’)(knexConnectOptions);
knex.from(‘cars’)
.select(“name”, “price”)
.where(‘id’, ‘=’, ‘6’)
.then((rows) => {
for (row of rows) {
console.log(`${row[‘name’]} ${row[‘price’]}`);
}
})
.catch((err) => { console.log( err); throw err })
.finally(() => {
knex.destroy();
process.exit();
});
— Mark Edwards
,
Oct 8, 09:54 AM
## Feathers Knex Raw Sql Examples 2022-11-10
(cross-referenced in https://github.com/edwardsmarkf/comptonTransAnlys-conversion/blob/main/raw-feathers-example)
0) Install feathers if not already done
npm install @feathersjs/feathers --save ;
1) Initialize new feathers environment
npm init --yes ;
npm install knex feathers-knex ;
2) create a username/password:
DROP USER IF EXISTS ‘knexUser’@‘localhost’ ;
CREATE USER ‘knexUser’@‘localhost’ IDENTIFIED BY ‘knexPassword’;
GRANT ALL ON `comptonTransAnlys`.* TO ‘knexUser’@‘localhost’
IDENTIFIED BY ‘knexPassword’ WITH MAX_QUERIES_PER_HOUR 0
MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 MAX_USER_CONNECTIONS 0 ;
GRANT ALL PRIVILEGES ON `comptonTransAnlys`.* TO ‘knexUser’@‘localhost’ ;
# to test:
# mariadb —host=localhost —user=knexUser —password=knexPassword comptonTransAnlys ;
3) Create feather application
feathers generate app ; ## probably select "n" for security, which can be created later
4) Create default Knex service
****** !!Only required if this is a NEW app, otherwise skip this entire step!! ******
feathers generate service ; ### create type "knex" named "knex-raw-init" and MariaDb"
4a) edit knex-raw-init.model.js
should look like this:
module.exports = function (app) {
return app.get('knexClient');
};
its possible
AFTER generating other calls that this file can (should?) be deleted
4b) move (or delete) directory
mv ./src/services/initialize-knex/ ./src/services/knex-raw-init-UNUSED/ ;
## -- or --
tar -zcvf knex-raw-init.gz ./src/services/knex-raw-init/ ;
## -- or/and --
rm -Rf ./src/services/knex-raw-init/ ;
4c) change index.js file
vi ./src/services/index.js ;
COMMENT OUT:
// const initializeKnex = require('./initialize-knex/initialize-knex.service.js');
// app.configure(knexInitialize);
4e) modify ./config/default.json to reflect the database access
(or answer this in the “generate service” prompt)
'connection': 'mysql://knexUser:knexPassword@localhost:3306/comptonTransAnlys'
-- or --
"mysql": {
"client": "mysql2",
"connection":
{ "host" : "localhost"
, "port" : 3306
, "user" : "knexUser"
, "password" : "knexPassword"
, "database" : "comptonTransAnlys"
}
}
5) Create our custom service!
feathers generate service ; ## create custom service named "my-custom-service"
5a) change my-custom-service.class.js file
./src/services/my-custom-service/my-custom-service.class.js :
/* eslint-disable no-unused-vars */
const { QueryTypes } = require(‘feathers-knex’); // new line!!
exports.MyCustomService = class MyCustomService {
constructor (options, app) { // formerly just constructor(options)
this.options = options || {};
this.app = app; // new line!
}
async find (key) { /* note the default is “params” you may need to change this */
/* Postman GET: http://123.123.123.123:3030/my-custom-service/?one=twooo
notice /?one=twoooo – last slash between service name and question mark is OPTIONAL!
*/
console.info(JSON.stringify(key.query) + ‘ in my find routine!!’);
const knexClient = this.app.get(‘knexClient’);
// const rows = await knexClient.raw(‘SELECT VERSION;’);
// https://knexjs.org/guide/raw.html#raw-parameter-binding ::
// Positional bindings ? are interpreted as values and ?? are interpreted as identifiers.
const sqlStatement = ‘SELECT variable_value FROM information_schema.global_variables WHERE ?? = ?;’ ;
const rows = await knexClient.raw( sqlStatement, [‘VARIABLE_NAME’, ‘VERSION’]);
// should execute this: SELECT variable_value FROM information_schema.global_variables where variable_name = ‘VERSION’ ;
console.table (rows);
return `${JSON.stringify(key.query) + JSON.stringify(rows)} find routine!!`;
}
async get (key) {
/* Postman GET: http://123.123.123.123:3030/my-custom-service/123456789
notice /123456789 – only ONE parameter as a suffix
*/
console.info(JSON.stringify(key) + ‘ in get routine!!’);
const knexClient = this.app.get(‘knexClient’);
const mariaDbDate = await knexClient.raw(‘SELECT CURDATE ;’ );
console.table(mariaDbDate);
return `${JSON.stringify(key) + JSON.stringify(mariaDbDate)} get routine!`;
}
};
6) stop firewall if necessary
systemctl stop firewalld ;
7) Start the app
run DEBUG=* npm start ;
run DEBUG=knex:query npm start ;
8) either postman or browser do:
http://123.123.123.123:3030/my-custom-service/1234 # get
http://123.123.123.123:3030/my-custom-service/?one=twoooooo # find
Optionally include parameters
/* named variables, please notice DOUBLE-COLON does backticks while SINGLE-COLON does quote characters! */
const sqlStatement = 'SELECT variable_value FROM information_schema.global_variables WHERE :var_name: = :val ;' ;
const sqlQuery = { var_name: 'VARIABLE_NAME' , val: 'VERSION' } ;
const rows = await knexClient.raw( sqlStatement, sqlQuery);
#########################################################################
easier to just generate…. to many steps to get this working.
4X) Create initial raw init model file (????)
mkdir --parent ./src/models/ ; // just in case this does not exist yet.
cat <<END > ./src/models/INIT-KNEX-RAW.model.js;
module.exports = function (app) {
return app.get('knexClient');
};
END
###############################################################################
## S E Q U E L I Z E:
0) npm install sequelize
1) create sequelize CUSTOM SERVICE named: “my-custom-service”
2) edit ./src/sequelize.js change logging false to logging true
3) change: src/services/my-custom-service/my-custom-service.class.js :
/* eslint-disable no-unused-vars */
const { QueryTypes } = require(‘sequelize’);
exports.MyCustomService = class MyCustomService {
constructor (options, app) {
this.options = options || {};
this.app = app;
}
async find (key) {
const sequelize = this.app.get(‘sequelizeClient’);
const stimwordPositionSelectFind =
‘SELECT * FROM stimwordPosition WHERE 1 AND stimwordPositionWord = $stimwordPositionWord;’ ;
const stimwordPositionSelectParms =
{ ‘stimwordPositionWord’ : JSON.parse(key.query).stimwordPositionWord } ;
const rows = await sequelize.query
( stimwordPositionSelectFind
, { ‘bind’ : stimwordPositionSelectParms }
);
return rows;
}
};
################################ browser-console:
in browser console (common initial setup for all examples)
[you may need to visit the “about:blank” webpage — 2022-22-21 ]
first visit http://123.123.123.123:3030/ to “initialize” chrome
[ ‘//cdnjs.cloudflare.com/ajax/libs/socket.io/2.0.4/socket.io.js’
, ‘//unpkg.com/@feathersjs/client@^3.0.0/dist/feathers.js’
].forEach( (src) => {
let script = document.createElement(‘script’); script.src = src; script.async = false;
document.head.appendChild(script);
});
const app = feathers(); const socket = io(); app.configure(feathers.socketio(socket));
// optional if trying to run on another http[s] webpage rather than at http://123.123.123.123:3030:
const socket = io.connect
( ’35.192.14.166:3030’ ,
{ ‘path’ : ‘/socket.io/’
, ‘port’ : ‘3030’
, ‘hostname’ : ’35.192.14.166’
, ‘secure’ : false
}
);
// socket.io.engine.transport
async function stimwordPositionFind(param) {
console.log( ‘param: ‘ + param);
let getResult = await app.service(‘my-custom-service’).find(param);
console.log(‘stimwordPosition function: ‘ + JSON.stringify(getResult) );
return getResult;
};
let stimwordPositionResult = null;
let key = { ‘query’ : { ‘stimwordWord’ : ‘horse’, ‘parm2’ : ‘answer2’ } } ;
stimwordPositionFind(key).then( value => { /* get(GET) */
stimwordPositionResult = value;
console.log(‘stimwordPosition(’ + key + ‘) : ‘ + JSON.stringify(stimwordPositionResult) );
});
async function stimwordPosition(id) { /* get(GET) (just one by index) */
console.log( ‘id: ‘ + id);
let getResult = await app.service(‘my-custom-service’).find(id);
console.log(‘stimwordPosition function: ‘ + JSON.stringify(getResult) );
return getResult;
};
############ GET GET GET GET GET GET
async get (id) {
const sequelize = this.app.get(‘sequelizeClient’);
const stimwordPositionSelectGet = `SELECT *
FROM stimwordPosition
WHERE 1
AND stimwordPositionAutoIncr = ${id};`;
const rows = await sequelize.query(stimwordPositionSelectGet);
return rows;
}
async function stimwordPosition(id) { /* get(GET) (just one by index) */
console.log( ‘id: ‘ + id);
let getResult = await app.service(‘my-custom-service’).get(id);
console.log(‘stimwordPosition function: ‘ + JSON.stringify(getResult) );
return getResult;
};
let stimwordPositionResult = null; let key = 1; // assuming your row ID is one
stimwordPosition(key).then( value => { /* get(GET) */
stimwordPositionResult = value;
console.log(‘stimwordPosition(’ + key + ‘) : ‘ + JSON.stringify(stimwordPositionResult) );
});
#####################################################
let stimwordPositionResult = null; let key = 1; // assuming your row ID is one
stimwordPosition(key).then( value => { /* get(GET) */
stimwordPositionResult = value;
console.log(‘stimwordPosition(’ + key + ‘) : ‘ + JSON.stringify(stimwordPositionResult) );
});
/notice object starting with “query” for the find:
let stimwordPositionResult = null; let key = { ‘query’ : ‘horse’ } ; // assuming your row ID is one
stimwordPositionFind(key).then( value => { /* get(
GET) */
stimwordPositionResult = value;
console.log(‘stimwordPosition(’ + key + ‘) : ‘ +
JSON.stringify(stimwordPositionResult) );
});
— Mark Edwards
,
Sep 27, 08:26 AM
the problem was trying to get the variables to process outside of the subshell, otherwise the value was not preserved!
https://unix.stackexchange.com/questions/16990/using-data-read-from-a-pipe-instead-than-from-a-file-in-command-options
https://stackoverflow.com/questions/69339514/saving-values-in-bash-shell-variables-while-using-tee
- cat test.txt:
first example line one
first example line two
first example line three
second example line one
second example line two
- test.bsh:
first=0;
second=0;
#while read -r line; do
while IFS=’‘ read -r line; do
[[ $line *'first example'* ]] && ((++first))
[[ $line ‘second example’ ]] && ((++second))
done < <(cat test.txt;) ## notice passing in command results using <() syntax.
echo $first ## should display 3
echo $second ## should display 2
— Mark Edwards
,
Aug 28, 08:00 AM
/* 2023-04-26 */
https://www.sitepoint.com/community/t/best-way-to-use-if-else-in-a-promise-chain/414101/8
/* 2023-04-25 */
// https://stackoverflow.com/questions/24928846/get-return-value-from-settimeout
( (delay) => { return new Promise((resolve, reject) => {
setTimeout(() => {
resolve(Math.floor(Math.random() * 2) ); /* returns a zero or a one BETTER WAY SEE SITEPOINT FORUM */
}, delay);
});
})(1500)
.then( (done) => { return ( ‘==>>’ + done )
})
.then( (last) => console.log(last) )
;
/* 2023-01-12a – async.await chaining */
const asyncFunction = (timeIn) => {
return new Promise( (resolve, reject) => {
setTimeout(() => {
resolve(++timeIn);
}, timeIn * 1000);
});
}
(async (value) => {
console.log(‘starting with: ‘, value);
const firstResult = await asyncFunction(value);
const secondResult = await asyncFunction(firstResult);
console.log(‘ending with:’, secondResult);
})(1);
/* 2023-01-12 – async-await chaining */
async function asyncCounterFunction(counter) {
return ++counter;
}
(async (initialData) => {
const firstTime = await asyncCounterFunction(initialData);
const secondTime = await asyncCounterFunction(firstTime);
const thirdTime = await asyncCounterFunction(secondTime)
console.info(await asyncCounterFunction(thirdTime))
console.log(‘Completion!’);
})(1)
async function testFunction(initialData) {
const firstTime = await asyncCounterFunction(initialData);
const secondTime = await asyncCounterFunction(firstTime);
const thirdTime = await asyncCounterFunction(secondTime)
console.info(await asyncCounterFunction(thirdTime))
console.log(‘Completion!’);
}
testFunction(1);
async function asyncCounterFunction(counter) {
try {
return ++counter;
} catch(e) { console.error(e)
}
}
/* 2023-01-10 – added async-await instead */
const myFunction = async (seconds) => { await setTimeout( () => { console.info(seconds, “done!”); }, seconds) } ; myFunction(2000) ;
/* one liner */
( async (seconds) => { await setTimeout( () => { console.info(seconds, “done!”); }, seconds) } )(2000)
/* old ugly way */
async function newFunction(seconds) { await setTimeout( () => { console.info(seconds, “done!”); }, seconds) } ; newFunction(2000) ;
==================================================================================
<<< leave this on top, fast & crude way to flatten out a promise! >>>
(async () => { try { let result = await feathersApp.logout(); console.log(‘the result is: ‘ + result) } catch (e) { console.log(e); } } ) () ;
(async () => let logoutResult = await feathersApp.logout(); console.log(logoutResult); })().catch(e => { console.log(e) });
===========================================================================================
2022-03-25:
const firstPromise = (promiseInput) => {
return new Promise( (resolve, reject) => { // long version
console.log(promiseInput);
let returnStuff = promiseInput + ‘ – parameter passed into first promise. ‘ ;
setTimeout( () => {
console.log (‘waiting a half-second, resolving: ‘ + returnStuff);
resolve (returnStuff);
},500 );
// we could use the “reject” function if this promise failed!
})
}
// shorter version per “windbeneathmywings”
const secondPromise = (promiseInput) => new Promise( (resolve, reject) => {
console.log(promiseInput);
let returnStuff = promiseInput + ‘ – parameter passed into second promise. ‘ ;
setTimeout( () => {
console.log (‘waiting a half-second, resolving: ‘ + returnStuff);
resolve (returnStuff);
},500 );
})
const thirdPromise = (promiseInput) => new Promise( (resolve, reject) => {
console.log(promiseInput);
let returnStuff = promiseInput + ‘ – parameter passed into third promise. ‘ ;
setTimeout( () => {
console.log (‘waiting a half-second, resolving: ‘ + returnStuff);
resolve (returnStuff);
},500 );
})
firstPromise(‘one’)
.then( value => { return secondPromise (value + ‘ two’) }) // long version
.then( value => thirdPromise (value + ‘ three’) ) // shorter version per “windbeneathmywings”
.then( value => console.log(’ FINAL result: ‘ + value) )
.catch( error => { console.log(’ ERROR! ‘ + error ) })
;
=================================================================================
// ======================================================
// ** 2021-09-14 10:47 AM return promise(dot)then example **
const promiseA = (parm) => {
return new Promise( (resolve, reject) => {
setTimeout( () => {
resolve(“promise-A “ + parm);
}, 1000 );
});
}
const promiseB = (parm) => {
return new Promise( (resolve, reject) => {
setTimeout( () => {
resolve(“promise-B “ + parm);
}, 2000 );
});
}
const promiseC = (parm) => {
return new Promise( (resolve, reject) => {
setTimeout( () => {
resolve(“promise-C “ + parm);
}, 3000 );
});
}
function getExample(initialParms) {
/* notice Promise-dot-then-dot-catch usage, NOT async/await usage */
// locally scoped
const results = {};
return promiseA(initialParms)
.then ( (resultA) => {
// add value to results object
results.a = resultA;
// pass result of this promise to next promise
return promiseB(resultA);
}
)
.then ( (resultB) => {
results.b = resultB;
return promiseC(resultB);
}
)
.then ( (resultC) => {
results.c = resultC;
// results object now contains all values from promise chain
return Promise.resolve(results);
}
)
.catch ( (error) => {
return Promise.reject(error);
}
)
;
}
let marksResults ; getExample(‘first parms entered’).then( (finalResults) => { marksResults = finalResults } ) ;
// =======================================================
// ** 2021-09-13 3:00 PM async/await example **
const promiseA = (parm) => { return new Promise((resolve, reject) => { setTimeout(resolve, 0500, ‘promise A ‘ + parm); }) };
const promiseB = (parm) => { return new Promise((resolve, reject) => { setTimeout(resolve, 0500, ‘promise B ‘ + parm); }) };
async function getExample(parm) {
/* notice async/await usage, not Promise-dot-then-dot-catch usage */
let resultA = await promiseA(parm);
console.log(‘first: ‘ + resultA);
// some processing
let resultB = await promiseB( parm + ‘-’ + resultA );
console.log(‘second: ‘ + resultB);
// more processing
return resultB // something using both resultA and resultB
}
let final ; getExample(‘123’).then ( (xx) => { final = xx ; } )
// =====================================================
// ** 2021-09-13 10am Promises.all example where parameters are not passed **
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise
my own example of “Promises.all”:
const promise1 = new Promise((resolve, reject) => { setTimeout(resolve( ‘promise one’), 0500 ); }); // notice different way for parm!
const promise2 = new Promise((resolve, reject) => { setTimeout(resolve, 6000, ‘promise two’); });
const promise3 = new Promise((resolve, reject) => { setTimeout(resolve, 8000, ‘promise three’); });
Promise.all([promise1, promise2, promise3])
.then ((values) => { console.log(values); })
.finally((values) => { console.log(‘here!’); }) ;
// ================================================================================
Chained Promises:
const myPromise = new Promise((resolve, reject) => {
setTimeout(() => {
resolve(‘foo’);
}, 300);
});
myPromise
.then(value => { return value + ‘ and bar’; })
.then(value => { return value + ‘ and bar again’; })
.then(value => { return value + ‘ and again’; })
.then(value => { return value + ‘ and again’; })
.then(value => { console.log(‘value: ‘ + value) })
.catch(err => { console.log(err) });
https://www.mariokandut.com/how-to-wait-for-multiple-promises-in-node-javascript/
How to use Promise.all
const all = Promise.all([
new Promise((resolve, reject) =>
setTimeout(() => resolve(1), 1000),
),
new Promise((resolve, reject) =>
setTimeout(() => resolve(2), 2000),
),
new Promise((resolve, reject) =>
setTimeout(() => resolve(3), 3000),
),
]).catch(err => console.log(‘Promise was rejected!’, err));
all.then(results => console.log(results)); // the output is: [1, 2, 3]
https://stackoverflow.com/questions/28250680/how-do-i-access-previous-promise-results-in-a-then-chain
A less harsh spin on “Mutable contextual state”
function getExample(){
//locally scoped
const results = {};
return promiseA(paramsA).then(function(resultA){
results.a = resultA;
return promiseB(paramsB);
}).then(function(resultB){
results.b = resultB;
return promiseC(paramsC);
}).then(function(resultC){
//Resolve with composite of all promises
return Promise.resolve(results.a + results.b + resultC);
}).catch(function(error){
return Promise.reject(error);
});
}
— Mark Edwards
javascript,
