How do you do block comments in YAML?

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How do I comment a block of lines in YAML?

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YAML supports inline comments, but does not support block comments.

From Wikipedia:

Comments begin with the number sign ( # ), can start anywhere on a line, and continue until the end of the line

A comparison with JSON, also from Wikipedia:

The syntax differences are subtle and seldom arise in practice: JSON allows extended charactersets like UTF-32, YAML requires a space after separators like comma, equals, and colon while JSON does not, and some non-standard implementations of JSON extend the grammar to include Javascript's /* ... */ comments. Handling such edge cases may require light pre-processing of the JSON before parsing as in-line YAML.

# If you want to write
# a block-commented Haiku
# you'll need three pound signs

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The spec only describes one way of marking comments:

An explicit comment is marked by a “#” indicator.

That's all. There are no block comments.

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Not trying to be smart about it, but if you use Sublime Text for your editor, the steps are:

1. Select the block
2. cmd+/ on Mac or ctrl+/ on Linux & Windows
3. Profit

I'd imagine that other editors have similar functionality too. Which one are you using? I'd be happy to do some digging.

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In Vim you can do one of the following:

• Comment all lines: :%s/^/#
• Comment lines 10 - 15: :10,15s/^/#
• Comment line 10 to current line: :10,.s/^/#
• Comment line 10 to end: :10,$s/^/#

or using visual block:

1. Select a multiple-line column after entering visual block via Ctrl+v.
2. Press r followed by # to comment out the multiple-line block replacing the selection, or Shift+i#Esc to insert comment characters before the selection.

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An alternative approach:

If

• your YAML structure has well defined fields to be used by your app
• AND you may freely add additional fields that won't mess up with your app

then

• at any level you may add a new block text field named like "Description" or "Comment" or "Notes" or whatever

Example:

Instead of

# This comment
# is too long

use

Description: >
  This comment
  is too long

or

Comment: >
    This comment is also too long
    and newlines survive from parsing!

More advantages:

1. If the comments become large and complex and have a repeating pattern, you may promote them from plain text blocks to objects
2. Your app may -in the future- read or update those comments

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One way to block commenting in YAML is by using a text editor like Notepad++ to add a # (comment) tag to multiple lines at once.

In Notepad++ you can do that using the "Block Comment" right-click option for selected text.

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For Visual Studio Code (VSCode) users, the shortcut to comment out multiple lines is to highlight the lines you want to comment and then press:

ctrl + /

Pressing ctrl + / again can also be used to toggle comments off for one or more selected lines.

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Emacs has comment-dwim (Do What I Mean) - just select the block and do a:

M-;

It's a toggle - use it to comment AND uncomment blocks.

If you don't have yaml-mode installed you will need to tell Emacs to use the hash character (#).

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If you are using Eclipse with the yedit plugin (an editor for .yaml files), you can comment-out multiple lines by:

1. selecting lines to be commented, and then
2. Ctrl + Shift + C

And to un-comment, follow the same steps.

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For RubyMine users on Windows:

Open file in editor Select the block and press Ctrl+forward slash, you will have selected block starting with #.

Now if you want to un-comment the commented block, press same key combination Ctrl+forward slash again

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In Azure Devops browser(pipeline yaml editor),

Ctrl + K + C Comment Block

Ctrl + K + U Uncomment Block

There also a 'Toggle Block Comment' option but this did not work for me.

There are other 'wierd' ways too: right click to see 'Command Palette' or F1

Then choose a cursor option.

Now it is just a matter of #

or even smarter [Ctrl + k] + [Ctrl + c]

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In .gitlab-ci.yml file following works::

To comment out a block (multiline): Select the whole block section > Ctrl K C

To uncomment already commented out block (multiline): Select the whole block section > Ctrl K U