Call a child component method from a parent in vuejs

Answer # 1

For small things, you can also call child component methods with $refs likethis. $refs.foo.bar ().
However, direct data reference between components is not recommended.

Component-Vue.js

  

However, it is also very important to keep the parent and child as separated as possible through a well-defined interface. This ensures that the code for each component is written and judged relatively independently. Therefore, components can be made more maintainable and potentially reusable

So basically

$emit from child to parent

Parent to child props

It may be good to pass data with

.

However, props cannot directly call child component methods.
Therefore, there is a way to use EventBus as shown below to coordinate processing between components.

Communication other than parent-child

var EventBus = new Vue ()
Object.defineProperties (Vue.prototype, {
    $bus: {
        get () {
            return EventBus
        }
    }
}
let ComponentY = Vue.extend ({
  mounted () {
    this. $bus. $on ('onMountedX', () =>{
        console.log ('onMountedX')
    })
  }
})
let ComponentX = Vue.extend ({
  mounted () {
    this. $bus. $emit ('onMountedX')
  }
  components: [ComponentY]
})

Answer # 2

Looks good with ref

Use vuex for more complex

Answer # 3

If you allow child components to be referenced with the ref attribute, you can call child methods from the parent
The following is a sample program.
The test method of the parent component App.vue calls the method of the child component Test.vue using $refs.

App.vue

<template>
  <div id = "app">
    <test ref = "test"></test>
    <button @ click = "test">test</button>
  </div>
</template>
<script>
import Test from "./Test.vue"
export default {
  methods: {
    test () {
      console.log ("parentMethod")
      this. $refs.test.childMethod ()
    },
  },
  components: {Test}
}
</script>

 

Execution sequence of Group By, Having and Where clause in SQL Server?

 FROM & JOINs determine & filter rows

WHERE more filters on the rows
GROUP BY combines those rows into groups
HAVING filters groups
ORDER BY arranges the remaining rows/groups
LIMIT filters on the remaining rows/groups

20 TOP MOST USED & COMMON SSH COMMANDS

As promised, I will teach babies* to manage unmanaged server from scratch. It means I’ll try to bring those babies from zero to hero being a Server Ninja. Hence, for my early posts I will firstly write all basic things for newbie server admins should know. In this page I list all necessary, most-used and common SSH commands useful to navigate through SSH client like Putty. I believe these commands are working on any Unix-based servers.

* babies = newbies with no knowledge about Linux and server at all

If you are really a newbie, then you should bookmark this page otherwise simply skip this post.

My next plan: I will post other articles of basic guides how to do things in your server via SSH. Browse it all here.

REQUIREMENTS TO SSH

• A working SSH client like Putty (Windows) or Terminal (Mac and Linux)
• A working Linux-based server with SSH enabled
• A cup of coffee if you wish
• A computer with stable Internet connection

SOME CONVENTIONS

1. Hit Enter or Return key on your keyboard after every each command / line
2. Each line is a single raw of command unless specified otherwise
3. Replace domain.com with your own domain name and TLD
4. Replace xxx.xxx.xxx.xxx with IP address of your own server
5. Replace example paths and file names according to your server information
6. If a path ends with slash “/” then its a directory
7. A directory: “/path/to/directory/” will always end with slash “/”
8. A file: “/path/to/file” won’t have slash “/” in the end
9. A file is not always having extension in the end of the file name

OK, so lets start with the most common commands to SSH you should know..

NAVIGATING

1. How to move into another directory
Use command below to change directory

1	cd [another directory]

example: move to directory “download”

1	cd download

2. How to go to home directory

1

cd ~

3. How go to the last directory you were in

1

cd -

4. How to go up a directory level

1

cd ..

5. How to show the full path of the current directory
Use this command to find out where are you currently in.

1

pwd

6. How to list files and/or directories in a directory

1	ls (just type ls and hit enter)

7. How to list all files and information

1

ls -al

8. How to list all files ending with certain extension

1

ls *.ext

example:

1

ls *.php

9. How to list all files and folders with detailed information including file size

1

ls -alh

10. How to quit and exit SSH client

1

exit

FILE MANAGEMENT

11. How to copy and rename file
Use this command to copy and rename a file

1	cp [filename] [new filename]

example: we’ll rename banner.jpg to banner728px.jpg

1	cp banner.jpg banner728px.jpg

example: we’ll cope banner.jpg to a folder called “ads”

1	cp banner.jpg ads/banner.jpg

example: copying and renaming at once

1	cp banner.jpg ads/banner728px.jpg

ps: original file will remain, it is just copied.

12. How to move and rename file
Use this command to move and rename file

1	mv [old filename] [new filename]

example: moving a file to another directory

1	mv banner.jpg ads/banner.jpg

example: moving a file to another directory and renaming it at once

1	mv banner.jpg ads/banner728px.jpg

ps: original file will be deleted as it was moved to another location
pps: you can also move a folder

example: moving “image” folder to “media” folder

1	mv image/ media

example: moving “image” folder to upper directory

1	mv image/ ..

13. How to delete / remove a file

1	rm [file name]

example:

1	rm banner.jpg

14. How to delete / remove all files in current directory

1

rm *

15. How to delete files with certain extension

1	rm *.extension

example: remove all files with .jpg extension

1

rm *.jpg

16. How to copy a folder with all files and folders in it

1	cp -r [directory] [new directory]

17. How to create new folder

1	mkdir [folder name]

example:

1	mkdir image

18. How to search for a file starting within current directory

1	find . -name [filename] -print

example: find a file called “banner.jpg” in current folder

1	find . -name banner.jpg -print

19. How to search for text within a file

1	grep [text] [filename]

example: find the word “sidebar” in file index.php

1	grep sidebar index.php

20. CHMOD – how to change file permission

1	chmod [permission type] [file/folder name]

example:

1	chmod 777 config.php

Available permission type: (below is not command)

1 2 3 4 5 6 7 8 9

First number is for the owner, second for the group, and third for everyone. 7 = Read + Write + Execute 6 = Read + Write 5 = Read + Execute 4 = Read 3 = Write + Execute 2 = Write 1 = Execute 0 = All access denied

http://www.servermom.org/top-most-used-common-ssh-commands/56/