How to incorporate user input in an input-mode Lua keymap in Neovim?

Question

In Vim, an input mode map can use <c-r>=input() to fetch user input and insert it at the cursor. How is this done in Neovim?

Specific Vimscript example:

imap <buffer> <unique> ;_ <c-r>="_{".input("sub:")."}"<cr>

What is the Neovim+Lua equivalent?

Answer 1

You can use vim.fn.input() to get the input and store it in a Lua variable. Then get the current cursor position in the current buffer with vim.api.nvim_win_get_cursor(0). Finally, set the text in the current buffer at the current cursor position using vim.api.nvim_buf_set_text().

Here is a complete mapping:

vim.keymap.set("i", "<C-r>", function()
    local user_input = vim.fn.input("Enter input: ")
    local row, col = unpack(vim.api.nvim_win_get_cursor(0))
    vim.api.nvim_buf_set_text(0, row - 1, col, row - 1, col, { "_{" .. user_input .. "}" })
end)

There's also the option to use vim.api.nvim_feedkeys() to insert the text into the buffer.