Typescript Middleware Pattern. NodeJS

 

Typescript !

Middleware Pattern, Typescript Implementation from scratch.

To apply in:

• Front or
• Back or
• Automation Tool or
• Command Line Tool
• My I have to use Command Pattern and Interpreter Pattern Mixed with Middleware Pattern.

Seems:

Like the old Filters in java web

But widely spread over platforms

Like the old Template in C++ .. ..

Reference:

• https://dev.to/lcanady/make-a-typescript-middleware-engine-21kb

• app.ts

// app.ts
import { pipeline } from './middleware';

interface Context {
  [key: string]: any; // Yes, I Love semicolons.!!
};

const engine = pipeline<Context>( async (ctx, next) => {
  ctx.first = "First things First!!";
  next();
} );
engine.use( async (ctx, next) => {
  ctx.second = "I am the developer:";
  next();
} );
engine.use( async (ctx, next) => {
  ctx.third = "https://github.com/maximilianou";
  next();
} );

console.log('Running.. TypeScript app');

(async () => {
  const context: Context = {};
  await engine.execute(context);
  console.log(context);
})();

• middleware.js

// middleware.ts
export type Next = () => Promise<any> | any;
export type Middleware<T> = (
  context: T,
  next: Next
) => Promise<void>;
export type Pipe<T> = {
  use: (...middlewares: Middleware<T>[]) => void;
  execute: (context: T) => Promise<void | T>
};
export function pipeline<T>(...middlewares: Middleware<T>[])
                  : Pipe<T> {
  const stack: Middleware<T>[] = middlewares;
  const use: Pipe<T>["use"] = (...middlewares) => {
    stack.push(...middlewares);
  }
  const execute: Pipe<T>["execute"] = async (context) => {
    let prevIndex = -1;
    const handler = async (index: number, context: T)
            : Promise<void | T> => {
      if(index === prevIndex){
        throw new Error("next() already called");
      }
      if(index === stack.length ){
        return context;
      }
      prevIndex = index;
      const middleware = stack[index];
      if(middleware){
        await middleware( context, () => handler( index+1, context ) );
      }
    };
    const response = await handler(0, context);
    if (response){
      return response;
    } 
  };
  return { use, execute };
}

• Makefile

api:
	mkdir api && cd api && npm -y init
	cd api && npm i express-openapi-validator	
	cd api && npm i @types/node typescript 
	cd api && npm install ts-node -D
	cd api &&  ./node_modules/.bin/tsc --init --rootDir src --outDir ./build --esModuleInterop --lib esnext --module esnext --noImplicitAny true
	cd api && mkdir src
	cd api && echo "console.log('Running.. TypeScript app')" > src/app.ts
	cd api && ./node_modules/.bin/tsc
	cd api && node ./build/app.js

• package.json

{
  "name": "api",
  "version": "1.0.0",
  "description": "",
  "main": "app.ts",
  "scripts": {
    "build":"./node_modules/.bin/tsc ",
    "start":"node ./build/app.js",
    "dev":  "./node_modules/.bin/ts-node ./src/app.ts",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@types/node": "^14.14.22",
    "express-openapi-validator": "^4.10.9",
    "typescript": "^4.1.3"
  },
  "devDependencies": {
    "ts-node": "^9.1.1"
  }
}

• tsconfig.json

{
  "compilerOptions": {
    /* Visit https://aka.ms/tsconfig.json to read more about this file */

    /* Basic Options */
    // "incremental": true,                   /* Enable incremental compilation */
    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
    "module": "commonjs",                       /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
    "lib": ["esnext"],                        /* Specify library files to be included in the compilation. */
    // "allowJs": true,                       /* Allow javascript files to be compiled. */
    // "checkJs": true,                       /* Report errors in .js files. */
    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    "outDir": "./build",                      /* Redirect output structure to the directory. */
    "rootDir": "src",                         /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    // "composite": true,                     /* Enable project compilation */
    // "tsBuildInfoFile": "./",               /* Specify file to store incremental compilation information */
    // "removeComments": true,                /* Do not emit comments to output. */
    // "noEmit": true,                        /* Do not emit outputs. */
    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */

    /* Strict Type-Checking Options */
    "strict": true,                           /* Enable all strict type-checking options. */
    "noImplicitAny": true,                    /* Raise error on expressions and declarations with an implied 'any' type. */
    // "strictNullChecks": true,              /* Enable strict null checks. */
    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
    // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */

    /* Additional Checks */
    // "noUnusedLocals": true,                /* Report errors on unused locals. */
    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
    // "noUncheckedIndexedAccess": true,      /* Include 'undefined' in index signature results */

    /* Module Resolution Options */
    "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
    "paths": {
      "@exmpl/*": ["src/*","build/*"]
    },                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    // "types": [],                           /* Type declaration files to be included in compilation. */
    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
    "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
    // "allowUmdGlobalAccess": true,          /* Allow accessing UMD globals from modules. */

    /* Source Map Options */
    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */

    /* Experimental Options */
    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */

    /* Advanced Options */
    "skipLibCheck": true,                     /* Skip type checking of declaration files. */
    "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
  }
}

• Result

$ npm run dev

> api@1.0.0 dev /home/maximilianou/projects/weekly27/api
> ts-node ./src/app.ts

Running.. TypeScript app
{
  first: 'First things First!!',
  second: 'I am the developer:',
  third: 'https://github.com/maximilianou'
}

Docker Github Container Registry Login

$ cat ~/personal_full.txt | docker login http://ghcr.io -u maximilianou --password-stdin
Login Succeeded

$ docker tag bf756fb1ae65 ghcr.io/maximilianou/node-lts-alpine:v14 

$ docker push ghcr.io/maximilianou/node-lts-alpine:v14

https://github.com/users/maximilianou/packages/container/package/node-lts-alpine


$ docker pull ghcr.io/maximilianou/node-lts-alpine:v14


FROM ghcr.io/maximilianou/node-lts-alpine:v14

Typescript - nodejs 2020 december

api/safeFetch.ts

• Code:

maximilianou@instrument:~/projects/weekly20$ cat api/safeFetch.ts 


import * as TE from "fp-ts/lib/TaskEither";
import * as E from "fp-ts/lib/Either";
const fetch = require('node-fetch');

type User = {

};

export const safeFetch = (
  url: string,
  errMessage: string
): TE.TaskEither> => 
     TE.tryCatch(
       () => fetch(url).then( res => res.json()),
       () => new Error(errMessage)
     );

safeFetch(
  "https://jsonplaceholder.typicode.com/users",
  "failed to fetch users"
)().then(E.fold(console.error, console.log));

• Run code, over command line:

maximilianou@instrument:~/projects/weekly20/api$ ./node_modules/.bin/ts-node safeFetch.ts

Ask me Anything - With Davy Engone

Public Learning: Work in progress

Work in progress

https://github.com/maximilianou/weekly20/

Typescript

React

Docker

docker-compose

nginx - loadbalancer - localmachine

planning to learn Github Action

planning to learn AWS

This way i take variable inside dockerfile, from the file in my machine, and from environment in aws

Makefile

vm:
	docker-compose --env-file .env.development up --build	

docker-compose.yaml

    build: # specify the directory of the Dockerfile
      context: .
      dockerfile: Dockerfile.dev
      args:
        - NPM_TOKEN_PARAM
        - NPM_MAIL_PARAM
        - NPM_USER_PARAM
    env_file: 
      - .env.development

. env.development

NPM_USER_PARAM=max...
NPM_TOKEN_PARAM=fe...
NPM_MAIL_PARAM=max..

Dockerfile.dev

ARG NPM_USER_PARAM
ARG NPM_TOKEN_PARAM
ARG NPM_MAIL_PARAM
ENV NPM_USER=$NPM_USER_PARAM
ENV NPM_TOKEN=$NPM_TOKEN_PARAM
ENV NPM_MAIL=$NPM_MAIL_PARAM
COPY .npmrc ./ 
RUN npm install npm-cli-login
RUN  ./node_modules/.bin/npm-cli-login -r https://npm.pkg.github.com -s @... -u ${NPM_USER} -p ${NPM_TOKEN}  -e ${NPM_MAIL}

React using state and props, Shopping Cart MVC 2019

React using state and props, Shopping Cart MVC 2019

I mean, the simplest example learning how to use the React state, and React props

( Clearly here i'm not using Redux, this is the next step, just to be clear )

React state of the App

React props of each React.Component Instance

So we can have list of products, and a shopping cart (list of items of products), adding and removing items.

The point is to learn how to pass action control over components, changing from state to new states on action events from components, to the Root App, and showing the change in the other affected Component.

https://codesandbox.io/s/v0l1knv1yl

https://github.com/maximilianou/react_2019_state_props_shoppingcart_mvc/

https://gitlab.com/maximilianou/react_2019_state_props_shoppingcart_mvc

https://bitbucket.org/maximilianou/react_2019_state_props_shoppingcart_mvc

import React from "react";
import ReactDOM from "react-dom";

import "./styles.css";

const ProductsList = props => {
  const { products, adding } = props;
  return (
    < section>
      < h2>List of Products< /h2>
      {products.map(product => (
        < article key={"product_" + product.id}>
          < h4>{product.name}< /h4>
          < span>{product.price}< /span>
          < button onClick={adding} value={JSON.stringify(product)}>
            +
          < /button>
        < /article>
      ))}
    < /section>
  );
};
const ItemsList = props => {
  const { items, removing } = props;
  return (
    < section>
      {items.map(item => (
        < article key={"item_" + item.product.id}>
          < h4>{item.product.name}< /h4>
          < span>{item.product.price}< /span>
          < span>{item.quantity}< /span>
          < span>{item.quantity * item.product.price}< /span>
          < button onClick={removing} value={JSON.stringify(item)}>
            -
          < /button>
        < /article>
      ))}
    < /section>
  );
};
class ShoppingCart extends React.Component {
  constructor(props) {
    super(props);
  }
  render() {
    return (
      < section>
        < h2>Shopping Cart< /h2>
        < ItemsList items={this.props.items} removing={this.props.removing} />
      < /section>
    );
  }
}
class App extends React.Component {
  state = {
    products: [
      { id: 20, name: "Limonade", price: 200 },
      { id: 21, name: "Green Tea", price: 150 },
      { id: 22, name: "Chocolate Milk", price: 350 }
    ],
    items: []
  };
  constructor(props) {
    super(props);
    this.adding = this.adding.bind(this);
    this.removing = this.removing.bind(this);
  }
  adding = evt => {
    const product = JSON.parse(evt.target.value);
    let item = this.state.items.find(ite => ite.product.id === product.id);
    if (item === null || item === undefined) {
      item = {};
      item.product = product;
    }
    if (item.quantity === undefined) {
      item.quantity = 1;
      this.setState({ items: [...this.state.items, item] });
    } else {
      item.quantity += 1; // mm.. here i'm changing the original object. mmm...
      this.setState({ items: [...this.state.items] });
    }
  };
  removing = evt => {
    const item_p = JSON.parse(evt.target.value);
    const item = this.state.items.find(
      ite => ite.product.id === item_p.product.id
    );
    if (item.quantity === 1) {
      const listItems = this.state.items.filter(
        ite => ite.product.id !== item.product.id
      );
      this.setState({
        items: listItems
      });
    } else {
      item.quantity -= 1; // mmm.. here i'm changing the original object. mmm...
      this.setState({ items: [...this.state.items] });
    }
  };
  render() {
    return (
      < div className="App">
        < ProductsList products={this.state.products} adding={this.adding} />
        < ShoppingCart items={this.state.items} removing={this.removing} />
      < /div>
    );
  }
}

const rootElement = document.querySelector("#root");
ReactDOM.render(<  App />, rootElement);