How to fold text in a JSON file?

Question

I have a large JSON file. It is not easy to work on all file at a time. I want to fold some content so that I can work on a section of JSON file.

E.g.:

{
  obj: {+}, // folded section
  obj:{
        // unfolded section
     }
}

Is it possible to fold JSON structure in Vim?

Answer 1

Yes, it is possible. A minimal setup would be:

:set filetype=json
:syntax on
:set foldmethod=syntax

Answer 2

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.

Ref:

https://github.com/nvim-treesitter/nvim-treesitter/issues/1337#issuecomment-864205387