In this post, I want to share how you can work effectively with JSON file inside Neovim.

Format JSON file

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Use Python json module

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If you have Python installed, you can use the following command to format JSON file:

:%!python -m json.tool

Use jq

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Otherwise, we need to install jq for this:

brew install jq

Then open the JSON file and run the following command:

:%!jq .

In the above command, % means the whole file, !{some-command} will run the text in the external some-command and write the output back to replace the original text. See also :help :range! inside neovim.

Define a command for this

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We can also define a command to format JSON file:

command! -range JSONFormat <line1>,<line2>!python -m json.tool

Then you can call %JSONFormat to format the JSON file.

Fold JSON file

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Use the syntax fold

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We can fold JSON file with the old syntax way:

set filetype=json
syntax on
set foldmethod=syntax

Use nvim-treesitter

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If you are using nvim and nvim-treesitter. You can also use treesitter to fold JSON files.

Config for nvim-treesitter:

require("nvim-treesitter.configs").setup {
  ensure_installed = { "python", "cpp", "lua", "vim", "json" },
  ignore_install = {}, -- List of parsers to ignore installing
  highlight = {
    enable = true, -- false will disable the whole extension
    disable = { 'help' }, -- list of language that will be disabled
  },
}

Make sure that JSON parser for treesitter is installed.

Then create after/ftplugin/json.vim with following config:

set foldmethod=expr
set foldexpr=nvim_treesitter#foldexpr()

Open a valid JSON file, you should be able to see the files are folded properly.

References

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• use external commands to modify text in vim: https://vi.stackexchange.com/a/7189/15292
• format JSON in vim: https://vi.stackexchange.com/q/16906/15292
• vim JSON format: https://salferrarello.com/vim-json-format/
• treesitter JSON fold setup: https://github.com/nvim-treesitter/nvim-treesitter/issues/1337#issuecomment-864205387
• how to fold text in JSON: https://vi.stackexchange.com/q/10562/15292