module_osmcal.lua

-- <includeonly>
local p = {}

function resultsAsTable(events)

    if (events == nil or events.data == nil) then
      return 
    end

    text = '{| class="wikitable" style="font-size:smaller"\n'
    text = text .. '|+ OSM Events\n'
    text = text .. '|-\n'
    text = text .. '! Date\n'
    text = text .. '! Title\n'
    text = text .. '! Location\n'
    text = text .. '! Venue\n'
    for _, result in ipairs(events.data) do
        local is_cancelled = ((result.cancelled == nil and false) or result.cancelled)
        text = text .. '|-'
        text = text .. '\n| ' .. result.date.human_short 
        text = text .. '\n| ' .. ((is_cancelled and '<s>') or '') .. '[' .. result.url .. ' ' ..  mw.text.nowiki(result.name) .. ']' .. ((is_cancelled and '</s>') or '')
        if result.location == nil then
          text = text .. '\n| '
          text = text .. '\n| '
        else
          text = text .. '\n| ' ..  result.location.short
          text = text .. '\n| ' ..  ((result.location.venue == nil and "") or result.location.venue)
        end
        text = text .. '\n'
    end
    text = text .. '|}\n'
    return text
end

function p.Events()
    local events = mw.ext.externaldata.getWebData {
         url = 'https://osmcal.org/api/v2/events/'
       , data = 'data=__json'
       , format = 'JSON'
    }
    return resultsAsTable(events)
end

return p
-- </includeonly>

Embedding:

<div style="padding: 0.5em 1em 0.5em 1em; border-radius: 0 0 0.2em 0.2em;">
<span style="font-size:smaller">
{{#invoke:PutModuleNameHere|Events}}
</span>
</div>

Renders as: