Friday Lua

A short while ago I was asked the following question,

"I use Trunk Notes to keep a log of my activities. I tag pages with 'log' and then have a page which lists all of those entries. It would be great if I could list the entries with the latest at the top."

This isn't something Trunk Notes can do out of the box; however with a bit of Lua scripting it's easily achieved.

In my wiki I have the following pages tagged with log:

• 18-11-2017
• 22-11-2017
• 24-11-2017
• 10-12-2017

I have a page which contains the following:

{% raw %}
{{tagged log}}
{% endraw %}

This lists the pages in alphabetical order, which isn't what I want. Although my pages have dates as titles (European format) I would rather Trunk Notes used the created date as the title shouldn't matter.

In order to do this I'm going to require the following to happen:

• Get a list of all the pages tagged with log
• Find out their created date
• Order these pages by their created date
• Output the list

Let's have a go using Lua by adding the following into the page LuaLog.lua:

{% raw %}

-- Get the titles of page which are tagged with log
page_titles = wiki.exprl('tagged', 'log')
-- Create an array of the page titles and created dates
pages = {}
for n, title in ipairs(page_titles) do
    page = wiki.get(title)
    table.insert(pages, { title = title, created = page.created })
end
-- Sort this by created in descending order (dates are just numbers)
table.sort(pages, function(page1, page2)
    return page1.created > page2.created
end)
-- Now prepare the Markdown list
output = ''
for n, page in ipairs(pages) do
   output = output .. " * [[" .. page.title .. "]]\n"
end
-- Return back to the calling page
return output

To use our new Lua function add {{lua LuaLog.lua}} to a page and you'll see your list of tagged pages with the most recently created at the top.
{% endraw %}

Done!

If you have any cool uses for Lua in Trunk Notes let me know.