How to create Preview window to display a string?

Question

I'm using a LSP plugin to call a command from the server, and currently it is logging the data using echom.

My current code is like this:

function! PtypeCallback(result)
    echom json_encode(a:result)
endfunction

It was working, but for functions with larger types, The JSON string is truncated. Also I want to keep it for some time, preferably launching it in a preview window.

How can I open the preview-window using a custom created buffer which contains the typ parameter from the JSON I'm receiving in a:result parameter?

Answer 1

After seven hours of fiddling with the documentation and searching, I was able to write a function that takes a filetype, an array of strings and show a dummy buffer based on that.

function! showInPreview(name, fileType, lines)
    let l:command = "silent! pedit! +setlocal\\ " .
                  \ "buftype=nofile\\ nobuflisted\\ " .
                  \ "noswapfile\\ nonumber\\ " .
                  \ "filetype=" . a:fileType . " " . a:name

    exe l:command

    if has('nvim')
        let l:bufNr = bufnr(a:name)
        call nvim_buf_set_lines(l:bufNr, 0, -1, 0, a:lines)
    else
        call setbufline(a:name, 1, a:lines)
    endif
endfunction

I wrote this function based on the rust plugin code I found in the LanguageClient_neovim plugin. Thanks @D._Ben_Knoble for suggesting the vim/nvim check in the function.

Hope this helps anyone looking for this answer. I can now call this function from my callback function with the correct lines and I'm ensured that it works for me.