Using tag="!!null" on a whole document to make nulls blank

[little-flag]

I want to take this:

title: A title
author: ""
pages: null

And get the output:

title: A title
author: 
pages: 

I found this example:

yq eval --null-input '.a="" | .a tag="!!null"'

But I don't understand how to do this for a whole document.

Many thanks in advance for any advice.

[mikefarah]

You can do it like this:

yq 'with(.. | select(tag == "!!null" or . == ""); . = "" | . tag="!!null")' data1.yaml

Explanation:

• .. | select(tag == "!!null" or . == "") - this matches all the nodes in the tree, and selects the ones that are either null or the empty string
• with(<exp>; blah) - this is a convenient way to make multiple updates to each match (doc)
• Then, within the with loop if you like, you update each element as you had.

[little-flag]

Thank you for the code and explanation but this is only working for me with the nulls, not the empty strings.

This:

echo "title: A title\nauthor: \"\"\npages: null" | yq 'with(.. | select(tag == "!!null" or . == ""); . = "" | . tag="!!null")'

Produces this:

title: A title
author: ""
pages:

[Rack34]

Mn