Formatting

FtVim uses conform.nvim for code formatting, providing fast and reliable formatting with support for many formatters.

Default Configuration

FtVim comes with these formatters pre-configured:

Language	Formatter
Lua	stylua
Shell/Bash	shfmt

These formatters are automatically installed via Mason. The extras add more: c_formatter_42 for C (42), clang-format for C++ (C++) and prettier for web files (Web).

Formatting Keymaps

Keymap	Mode	Description
<leader>cf	Normal, Visual	Format buffer or selection
<leader>uf	Normal	Toggle format on save

Manual Formatting

To format the current buffer, press <leader>cf in normal mode.

To format a selection, select the text in visual mode and press <leader>cf.

You can also use the command:

:lua require("conform").format()

Format on Save

Format on save is disabled by default in FtVim. Toggle it for the session with <leader>uf, or enable it permanently in ~/.config/nvim/lua/config/options.lua:

vim.g.ftvim_autoformat = true

To enable or disable it for a single buffer, set vim.b.ftvim_autoformat (it overrides the global option):

vim.api.nvim_create_autocmd("FileType", {
  pattern = { "markdown" },
  callback = function()
    vim.b.ftvim_autoformat = false
  end,
})

Custom Format on Save

For full control, override conform's format_on_save (this replaces FtVim's toggle):

-- ~/.config/nvim/lua/plugins/formatting.lua
return {
  {
    "stevearc/conform.nvim",
    opts = {
      format_on_save = {
        timeout_ms = 500,       -- Timeout for formatting
        lsp_format = "fallback", -- Use LSP if no formatter is configured
      },
    },
  },
}

Disable Format on Save for Specific Filetypes

return {
  {
    "stevearc/conform.nvim",
    opts = {
      format_on_save = function(bufnr)
        -- Disable for certain filetypes
        local ignore_filetypes = { "sql", "java" }
        if vim.tbl_contains(ignore_filetypes, vim.bo[bufnr].filetype) then
          return nil
        end
        return {
          timeout_ms = 500,
          lsp_format = "fallback",
        }
      end,
    },
  },
}

Adding New Formatters

Step 1: Install the Formatter

Add the formatter to Mason's ensure_installed list:

return {
  {
    "mason-org/mason.nvim",
    opts = {
      ensure_installed = {
        "prettier",    -- JavaScript/TypeScript/JSON/etc.
        "black",       -- Python
        "clang-format", -- C/C++
      },
    },
  },
}

Or install manually via :Mason.

Step 2: Configure the Formatter

Add the formatter to conform.nvim:

return {
  {
    "stevearc/conform.nvim",
    opts = {
      formatters_by_ft = {
        javascript = { "prettier" },
        typescript = { "prettier" },
        json = { "prettier" },
        python = { "black" },
        c = { "clang-format" },
        cpp = { "clang-format" },
      },
    },
  },
}

Using Multiple Formatters

Run formatters in sequence:

formatters_by_ft = {
  python = { "isort", "black" }, -- Run isort first, then black
}

Use the first available formatter:

formatters_by_ft = {
  javascript = { "prettierd", "prettier", stop_after_first = true },
}

Customizing Formatter Options

Override formatter settings:

return {
  {
    "stevearc/conform.nvim",
    opts = {
      formatters = {
        stylua = {
          prepend_args = { "--indent-type", "Spaces", "--indent-width", "2" },
        },
        shfmt = {
          prepend_args = { "-i", "2" }, -- 2-space indent
        },
        prettier = {
          prepend_args = { "--tab-width", "2", "--single-quote" },
        },
      },
    },
  },
}

Disabling Formatting

For Specific Filetypes

return {
  {
    "stevearc/conform.nvim",
    opts = {
      formatters_by_ft = {
        -- Set to empty table to disable
        markdown = {},
      },
    },
  },
}

Disable LSP Fallback

return {
  {
    "stevearc/conform.nvim",
    opts = {
      default_format_opts = {
        lsp_format = "never", -- Don't use LSP for formatting
      },
    },
  },
}

Troubleshooting

Check Conform Status

:ConformInfo

Shows configured formatters and their status for the current buffer.

Common Issues

Formatter not working:

1. Check :ConformInfo to see if the formatter is detected
2. Ensure the formatter is installed (:Mason)
3. Verify the formatter binary is in your PATH

Formatting slow:

1. Some formatters (like prettier) can be slow on large files
2. Consider using faster alternatives (e.g., prettierd instead of prettier)
3. Increase timeout_ms if needed

Format on save not working:

1. Ensure it is enabled (<leader>uf or vim.g.ftvim_autoformat = true), it is disabled by default
2. Check :ConformInfo for the formatter status
3. Look for errors with :messages

Recommended Formatters by Language

Language	Formatter	Notes
Lua	stylua	Default in FtVim
Shell/Bash	shfmt	Default in FtVim
JavaScript/TypeScript	prettier or prettierd	prettierd is faster
Python	black or ruff_format	ruff is faster
Go	gofmt or goimports	goimports also organizes imports
Rust	rustfmt	Comes with Rust toolchain
C (42)	c_formatter_42	42 extra
C/C++	clang-format	Highly configurable, C++ extra
JSON	prettier or jq	jq for JSON-only projects
YAML	prettier or yamlfmt
Markdown	prettier
HTML/CSS	prettier

Example: Complete Formatting Setup

Here's a full example for a web development setup:

return {
  -- Install formatters
  {
    "mason-org/mason.nvim",
    opts = {
      ensure_installed = {
        "prettierd",
        "eslint_d",
      },
    },
  },

  -- Configure formatting
  {
    "stevearc/conform.nvim",
    opts = {
      formatters_by_ft = {
        javascript = { "prettierd" },
        typescript = { "prettierd" },
        javascriptreact = { "prettierd" },
        typescriptreact = { "prettierd" },
        json = { "prettierd" },
        html = { "prettierd" },
        css = { "prettierd" },
        markdown = { "prettierd" },
      },
    },
  },
}

Then enable format on save with vim.g.ftvim_autoformat = true or <leader>uf.

tip

The Web extra already sets up prettier for these filetypes.