Angular 7 App ng build Works But ng build --prod Gives Error

Hello,

Recently I was trying to generate production build of one of our older Angular app which was built on Angular 6 and later upgraded to Angular 7. When we run ng build it works fine but when we run ng build --prod it gives so many errors.

Here in this blog I am going to explain what are those errors and how I solved it.

Problem 1 : Strict Parameter checking for function.

There were few events and handler defined in the app where there were parameter mismatch. For example in html file we have following event.

<componentName (event)="eventHandler($event)"></componentName >

And in component TS file event handler was defined like this

eventHandler() {
}

As you can see from html file it was passing $event param but on handler param was not mentioned. So make sure that your function signature and function declaration matches.

Problem 2 : Duplicate Declaration of Components

By mistake we have duplicate declaration of components in both App module and and other child modules of the app. Make sure you either declare all your components to app module or if you are defining it into sub module then make sure you remove it from app module.

Problem 3 : Cannot read property 'moduleType' of undefined

When you face above issue please check your app module by mistake you may have defined following line twice in your app module.

platformBrowserDynamic().bootstrapModule(AppModule);

It's like you are trying to bootstrap your Angular app twice and it gives above error. So try to avoid it.

Problem 4 : Enable IVY

In Angular 7 by default IVY is disabled hence even if you generate production build you app size it bit large. To enable IVY add following line to your tsconfig.json file.

"angularCompilerOptions": {
    "enableIvy": true
}

Hope this blog post helps you.

NodeJs MySQL Observer

Hello,

In this blog we are going to learn how to use NodeJs to observe changes in MySql databases. This is useful when you want to track MySQL changes and based on that want to send some events to frontends or want to do any other actions.

For this first of all you have to enable binary logging in you database. Binary logging is very much useful for real time MySQL replication. In Amazon RDS, it's by default available and you can switch on it from configurations. For your local database if you are using MAMP, you can do following trick.

Create a file with name my.cnf and add following content to it.

[mysqld]
server-id = 1
default-storage-engine = InnoDB
log-bin=bin.log
log-bin-index=bin-log.index
max_binlog_size=100M
expire_logs_days = 10
binlog_format=row
socket=mysql.sock

Add this file to conf folder of your MAMP directory and restart MySQL server. This will enable binary logging in your database.

Now to observe this changes we use npm package called zongji . Install it with NPM.

Add following code to your NodeJs script.

var ZongJi = require('zongji');
var _underScore = require('underscore');

var zongji = new ZongJi({

    user : 'YOUR_USERNAME',

    password : "YOUR_PASSWORD",

    database: 'YOUR_DATABASE',

    socketPath : '/Applications/MAMP/tmp/mysql/mysql.sock'

});

Now add event on binlog.

zongji.on('binlog', function(evt) {

});

This event is triggered whenever there is a change in any of your database tables.

Inside this event you can have logic of checking new rows, updates rows, deleted rows.

zongji.on('binlog', function(evt) {

if (evt.getEventName() === 'writerows' || evt.getEventName() === 'updaterows' || evt.getEventName() === 'deleterows') {

var database = evt.tableMap[evt.tableId].parentSchema; 

        var table =  evt.tableMap[evt.tableId].tableName; 

        var columns = evt.tableMap[evt.tableId].columns; 

        _underScore.each(evt.rows, function(row) {
        });
}
});

At last start the process and pass the events you want to watch.
zongji.start({
  includeEvents: ['tablemap', 'writerows', 'updaterows', 'deleterows']
});

ReactJs Material UI Table Infinite Scroll

Hello,

Recently in one of my ReactJs project, I faced a challenge in implementing infinite scroll in Material UI table. In this blog I am going to mention trick I have used.

First of all I was really surprised to see that Material UI table does not have infinite scroll function out of the box. It's very much needed. Sometimes something can not be achieved with frameworks, can be achieved via basics of JavaScript. In this I have done something similar.

I tried adding on scroll events on Table, Table Body but it didn't work. I also tried adding refs to body and then bind the Scroll event but that also did not work. After struggling for couple of hours, I finally decided to it with Pure JavaScript.

Step 1 : Wrap material UI table inside the container with fixed height and set overflow = scroll to container.


import styled from "styled-components";

export const Table = props => (
  <TableWrapper id={props.id}>
    <MuiTable {...props}/>
  </TableWrapper>

);

const TableWrapper = styled.div`
  max-height: 500px;
  overflow: scroll;

  ::-webkit-scrollbar {
    width: 3px;
    height: 3px;
  }
`;

As you can see I created a wrapper of table and set max height to it. You can make it dynamic as well depending on window height.

Step 2: Import Table to your component

import {
  Table

 } from './components/Table';

return (
          <>         
             <Table id={"tableID"}/>
          </>
        );

Step 3: Bind scroll event to wrapper

let me = this;
document.getElementById('tableID').onscroll = function(event){
   if(this.scrollTop == (this.scrollHeight - this.clientHeight)){
         //User reached bottom of table after scroll
         //Logic to call web services to get next set of data
   }
};

Hope this helps you.

ReactJs / Angular - Override Material UI Theme

Hello,

While working with React or Angular Applications we normally uses Material UI themes and components and it's great choice because it has nice set of themes and colors and ready to use components. That makes our life easy.

One challenge we face is, in case if we want to change or override the theme. For example Material ui has dark blue theme. What if you want to change colors or dark blue theme with your own color. One option is you can declare the class with same name and give your own property. However the better solution is to use theme override. In this blog I am going to mention how to this.

Please note the method I am going to mention here is specific to React application.

First of all create theme.js file in your app and add following code to it.

import React from "react";
import { MuiThemeProvider, createMuiTheme } from "@material-ui/core/styles";
import CssBaseline from "@material-ui/core/CssBaseline";
import blueGrey from "@material-ui/core/colors/blueGrey";
import lightBlue from "@material-ui/core/colors/lightBlue";
import "typeface-roboto";

import { ThemeProvider as ScThemeProvider } from "styled-components";

export default props => (
  <ScThemeProvider theme={muiTheme}>
    <MuiThemeProvider theme={muiTheme}>
      <CssBaseline>{props.children}</CssBaseline>
    </MuiThemeProvider>
  </ScThemeProvider>
);

const theme = {
  overrides: {

  },

  palette: {

    primary: { 

      main: '#MAIN_COLOR' 

    }, 

    secondary: { 

      main: '#SECONDARY_COLOR' 

    },

    background: {

      default: '#BACKGROUND_COLOR'

    }

  },

  type: "dark"

};

const muiTheme = createMuiTheme(theme);

Now here in overrides you can add code to override. For example if you want to change panel header. If you inspect html element you will find it has a class MuiPaper-root

Here is how you can override base CSS of it.

   overrides: {

    MuiPaper: {

      root: {

        background: '#YOUR_COLOR'

      },

      rounded: {

        background: '#YOUR_COLOR'

      }

    }

Same way for any other components you can do it. Inspect the HTML structure, find out Class Name and override it.