nixos-laptop/modules/home-manager/neovim/none-ls.lua

-- renamed to none-ls
local null_ls_status_ok, null_ls = pcall(require, "null-ls")
if not null_ls_status_ok then
	return
end

local formatting = null_ls.builtins.formatting
local diagnostics = null_ls.builtins.diagnostics
local code_actions = null_ls.builtins.code_actions

-- to setup format on save
local augroup = vim.api.nvim_create_augroup("LspFormatting", {})

require("null-ls").setup({
	sources = {
		formatting.stylua,
		formatting.black,
		formatting.nixpkgs_fmt,
		formatting.mix,
	},

	-- configure format on save
	on_attach = function(current_client, bufnr)
		if current_client.supports_method("textDocument/formatting") then
			vim.api.nvim_clear_autocmds({ group = augroup, buffer = bufnr })
			vim.api.nvim_create_autocmd("BufWritePre", {
				group = augroup,
				buffer = bufnr,
				callback = function()
					vim.lsp.buf.format({
						filter = function(client)
							--  only use null-ls for formatting instead of lsp server
							return client.name == "null-ls"
						end,
						bufnr = bufnr,
					})
				end,
			})
		end
	end,
})

-- formatting command
vim.api.nvim_create_user_command("Format", function()
	vim.lsp.buf.format(nil, 10000)
end, {})

vim.keymap.set(
	"n",
	"<leader>fm",
	":Format<CR>",
	{ desc = "Format current buffer (also done on save)", noremap = true, silent = true }
)