VimWiki - create a "smart" index page for subdir/section of wiki?

Question

I'm using VimWiki for a writing project and for certain sections (like "chapters", contained in sub-directories) I want to create indexes that work similarly to the way VimWiki's diary index works. Unfortunately in reading through the plugin's source I haven't been able to understand how the VimwikiDiaryGenerateLinks function works in order to replicate it for something similar.

My exact goal is this:
In my vimwiki section index page I want to automatically create links to files that match a pattern...

for all files like:

~/Documents/wiki/subdir1/string_xyz123.mkd
~/Documents/wiki/subdir1/string_xyz456.mkd
~/Documents/wiki/subdir1/string_xyz789.mkd

I want to create a list of links in vimwiki markdown like this:

- [xyz123](string_xyz123.mkd)
- [xyz456](string_xyz456.mkd)
- [xyz789](string_xyz789.mkd)

Sometimes I'll create new string_xyz789.mkd pages from someplace other than this index file, so I want this index file to keep itself updated automatically (the way VimWiki's "diary" index file automatically lists all the diary entries that exist).

The index page as a whole will be structured somewhat like this:

# Page Title

Some various content... perhaps multiple paragraphs...

## Automatically generated list of links
- [xyz123](string_xyz123.mkd)
- [xyz456](string_xyz456.mkd)
- [xyz789](string_xyz789.mkd)

Other content that I type manually.

...and only the auto-generated list of links should be updated. I need to be able to type content before and after the list as if I'm just editing a normal wiki page.

Does VimWiki provide a solution for this?

If not could you suggest how to approach scripting this myself?

Answer 1

I haven't had time to test more than the first code-block, but the others are mostly mechanical transformations.

function MyLinks(pat, strip) abort
  return glob(a:pat, v:false, v:true)
        \ ->map({_, v -> printf('[%s](%s)', fnamemodify(v, ':t:r')->substitute(printf('^%s', a:strip), '', ''), fnamemodify(v, ':t'))})
        \ ->join("\n")
endfunction

Extracting formatting functions:

function MakeLink(text, filename) abort
  return printf('[%s](%s)', a:text, a:filename)
endfunction

function Basename(filename) abort
  return fnamemodify(a:filename, ':t')
endfunction

function NoExt(filename) abort
  return fnamemodify(a:filename, ':r')
endfunction

function MyLinks(pat, strip) abort
  return glob(a:pat, v:false, v:true)
        \ ->map({_, v -> MakeLink(NoExt(Basename(v))->substitute(printf('^%s', a:strip), '', ''), Basename(v))})
        \ ->join("\n")
endfunction

You could avoid the lambda by doing

function MyLinks(pat, strip) abort
  return glob(a:pat, v:false, v:true)
        \ ->map(printf('MakeLink(NoExt(Basename(v:val))->substitute("^%s", "", ""), Basename(v:val))', a:strip))
        \ ->join("\n")
endfunction

(and see :help method for how to get rid of all the other ->s in older vim's; in most cases, you substitute the left expression as the first argument in the right function call, giving

function MyLinks(pat, strip) abort
  return join(
        \ map(
        \   glob(a:pat, v:false, v:true),
        \   printf('MakeLink(substitute(NoExt(Basename(v:val)), "^%s", "", ""), Basename(v:val))', a:strip),
        \ "\n")
endfunction

)

You supply pat (a glob, see :help glob()) and strip (a pattern to strip, :help substitute()). An example:

:put =MyLinks($HOME.'/Documents/wiki/subdir1/string_xyz*.mkd', 'string_')

How? We

1. glob the pattern as a list (change v:false to v:true depending on how you feel about 'suffixes' and 'wildignore')
2. map the results into a link format using fnamemodify and substitute
3. join the list with newlines to make it putable text (this last step is unnecessary for put = or append(); I almost just left it as list of [k, v] pairs)

---

If needed you could modify to give more substitute parameters for more control

function MyLinks(pat, spat, ssub, sflags) abort
  return glob(a:pat, v:false, v:true)
        \ ->map({_, v -> printf('[%s](%s)', fnamemodify(v, ':t:r')->substitute(a:spat, a:ssub, a:sflags), fnamemodify(v, ':t'))})
        \ ->join("\n")
endfunction

Up to you to make any necessary transformations, for now, as it takes me a bit of work.

---

For automatically updating it, you could try something like

augroup UpdateThing
  autocmd!
  autocmd BufEnter my-index /## Automatically generated list of links/+;'}- delete
        \ | put! =MyLinks('...', '...')
augroup END

How?

On BufEnter of my-index, we delete from the line below ## Automatically generated list of links to the end of the paragraph and put our list of links.

(The original version used two commands to delete: the first /…/+ moved to the line after the header, while the second .,'}- delete deleted from that line to the line before the paragraph break. The newer version uses ; to separate addresses rather than ,—the difference is documented at :help :;. Effectively, it allows the second address to start relative to the first.)