In the first part I am explaining how to do export and import using js.
here is my sample module ‘myutile.js‘
const myMethod1 = () => {
console.log('Hi 1')
}
const myMethod2 = () => {
console.log('Hi 2')
}
const myData = {
name:'myname',
age:22
}
module.exports = {
myMethod1,
myMethod2,
myData
};
we can import all from the above module
var access1 = require('./myutile');
access1.myMethod1();
access1.myMethod2();
console.log(access1.myData);
output:
And also we can import only the specific function/data . for example I need to import only the `myMethod2()` and `myData` from the module
var m2 = require('./myutile').myMethod2;
var data = require('./myutile').myData;
m2();
console.log(data);
output:
Using Typescript
sample module ‘myutile.js’
export const myMethod1 = () => {
console.log('Hi 1')
}
export const myMethod2 = () => {
console.log('Hi 2')
}
export const myData = {
name: 'myname',
age: 22
}
export default {
myMethod1,
myMethod2,
myData
};
import allUtiles from './myutile'; allUtiles.myMethod1(); allUtiles.myMethod2(); console.log(allUtiles.myData);
output
import * as allUtiles from './myutile'; allUtiles.myMethod2(); allUtiles.myMethod1(); console.log(allUtiles.myData);
output
import {myMethod1,myData} from './myutile';
myMethod1();
console.log(myData);
In this sample I am using a node module called ‘ ExcelJS‘. This will stream the data to the file instead of big data in memory (if we are keeping large amount of data in memory, we may get `JavaScript heap out of memory` exception ) this will write to the file
Install the module using npm
npm install exceljs --save
then in the node application just import the module
const Excel = require('exceljs');
const options = {
filename: 'myfile.xlsx',
useStyles: true,
useSharedStrings: true
};
const workbook = new Excel.stream.xlsx.WorkbookWriter(options);
const worksheet = workbook.addWorksheet('my sheet');
worksheet.columns = [
{ header: 'Id', key: 'id' },
{ header: 'First Name', key: 'first name' },
{ header: 'Phone', key: 'ph' }
]
var data;
for(let i = 1; i<= 10; i++){
data = {
id: i,
'first name': "name "+i,
ph: "012014520"+i
};
worksheet.addRow(data).commit();
}
workbook.commit().then(function() {
console.log('excel file cretaed');
});
we can use the same module in typescript also
refer : exceljs
Codeigniter create custom config
Create config file in ‘application\config’ folder, give any name (for example I have given ‘cust_settings.php’ [application\config\cust_settings.php] )
<?php
if (!defined('BASEPATH')) exit('No direct script access allowed');
$config['site_name'] = 'My website';
$config['protocol'] = 'smtp';
$config['smtp_host'] = 'smtp1.server.com';
$config['smtp_user'] = 'username';
$config['smtp_pass'] = 'password';
$config['smtp_port'] = '25';
You can use ‘config->load()’ function to load the configuration and ‘$this->config->item()’ to retrieve the configuration values
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Welcome extends CI_Controller {
public function index()
{
// Loads a config file named cust_settings.php and assigns it to an index named "cust_settings"
$this->config->load('cust_settings', TRUE);
// Retrieve a config item named site_name contained within the cust_settings array
$site_name = $this->config->item('site_name', 'cust_settings');
echo $site_name."<br><br>";
// An alternate way to specify the same item:
$cust_settings = $this->config->item('cust_settings');
//$site_name = $cust_settings['site_name'];
echo "<pre>";
print_r($cust_settings);
echo "</pre>";
$this->load->view('welcome_message');
}
}
Output
For using this we can load multiple configuration files
ref: codeigniter.com
In the bellow example, getting list of person id not exist in the given list
SELECT E.person_id
FROM (VALUES
(661),
(1826),
(2036),
(2567),
(2922),
(3408)
) E(person_id)
WHERE NOT EXISTS
(
SELECT 1
FROM persontable P
WHERE E.person_id = P.id
)
SELECT E.email
FROM (VALUES
('[email protected]'),
('[email protected]'),
('[email protected]'),
('[email protected]')
)
E(email)
WHERE NOT EXISTS
(
SELECT 1
FROM person P
WHERE E.email = P.emailid
)
tested in PostgreSQL
Add the following code in function.php to enable or start session in wordpress
add_action('init', 'activate_session', 1);
function activate_session() {
if(!session_id()) {
session_start();
}
}
This is a basic example for beginners for creating a basic java spring boot application using ‘spring-boot-starter-parent’.
In this tutorial I am using Spring tool suite as my IDE.
I.1: File->New -> Maven Project (You can do it by write clicking in the blank space of Package Explorer )
I.2: I have selected ‘create a simple project ( skip archetye selection)’ this allow me to kip the Archetype selection
I.3 : Setting group id and artifact id and other project related details
Done with the maven project creation, you can see the IDE automatically create the project folder structure like bellow .
You can see the project details in pom.xml file
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mytutor</groupId>
<artifactId>my-project</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>My Project</name>
<description>some description</description>
<properties>
<java.version>1.8</java.version> <!-- Setting java version -->
</properties>
<parent> <!-- here we are saying our project is a child of the spring-boot-starter-parent project -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.3.RELEASE</version>
</parent>
<dependencies>
<dependency> <!-- Adding spring boot dependency -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
</project>
write click on project folder->Maven->Update Project
After update we can see JRe updated to 1.8 and added Maven Dependencies
Now we can create our application entry point
Crate a class like bellow (sselect the tic ‘public static void main’ to auto generate the function)
Right click in Package Explorer -> New ->Class
Then add @SpringBootApplication annotation to the class and add SpringApplication.run(MyApp.class, args); inside the main function
package com.mytutor;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class MyApp {
public static void main(String[] args) {
// TODO Auto-generated method stub
SpringApplication.run(MyApp.class, args);
}
}
Now we can create our controller
Right click in Package Explorer -> New ->Class
Add the following code in the file
package com.mytutor.controllers;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class MyFirstController {
@RequestMapping("/home") //Request mapping https://localhost/home
String myHome() {
return "Hello World!";
}
}
You are done
Now we can run our application You can press the Green *Play button 
Or you can right click the project folder and select the Run As – >Java Application
Tadaaaaa! Our project is running
Now we can hit the url
We and run Spring boot application from command line also by using the command mvn spring-boot:run
Done
Note
If you are getting the error “Exception in thread “main” java.lang.NoClassDefFoundError: ch/qos/logback/classic/turbo/TurboFilter ” please add the logback-classic dependency in pom file
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!-- Exception in thread "main" java.lang.NoClassDefFoundError: ch/qos/logback/classic/turbo/TurboFilter --> <!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic --> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.2.3</version> <scope>test</scope> </dependency> </dependencies>