* Format JSON with Python (oneliner)

I’m experimenting with getting by without Language Server Protocol (LSP), and today I came a accross a large JSON file that was compressed into a single line. As I usually do I typed <leader>+f to make the LSP format the file.. I soon realized that I had to find another way without my LSP.

So I came across this python3 module json.tool that can format JSON input.

To format a file:

python3 -m json.tool unformatted.json > formatted.json

To format from stdin:

cat unformatted.json | python3 -m json.tool -- > formatted.json

We can also do it from within vim thanks to vim’s support of external commands. Let’s say we have the following line in our editor.

{ "name": "claw0ry", "website": "https://claw0ry.net"}

Let’s select the line with V and then type

:'<,'>!python3 -m json.tool --

And VOILA, the data is formatted.

{
    "name": "claw0ry",
    "website": "https://claw0ry.net"
}

Alternative

Another alternative is to use jq which is way less characters to type, but it requires you to have the tool installed and the python module is built-in.