Azure table storage use as cache

azure-cache.lua

local ACCOUNT='youraccount'
local KEY='youkey'

local azure = require('niiknow/webslib/azure.lua')

-- PrimaryKey is db like in redis, if not provided set to -default
local pKey = request.query['db'] or '-default'

-- RowKey is the actual key
local rKey = request.query['key']

-- GET cache item
if (request.method == 'GET') then
  local search = string.format("(PartitionKey eq '%s' and RowKey eq '%s')", pKey, rKey)
  local tst = azure.table.list(
   {account = ACCOUNT, key = KEY, table = 'CacheFun'}
   , {filter = search})
  
  -- validate that it has not expired then return
	-- else proceed to delete
  local item = json.parse(tst.content)
  local result = item.value[1] -- array start at 1, weird
  if (result ~= nil and result.exp > os.time()) then
    return result.content
  end
end

-- if there is a content body, save it to cache
if (request.body) then
	local expire = request.query['exp'] or 120 -- expire in seconds, default expire to 2 minutes
	local payload = {
  content = request.body,
  PartitionKey = pKey,
  RowKey = rKey,
  exp = os.time() + expire
}

azure.table.update(
 {account = ACCOUNT, key = KEY, table = 'CacheFun'}
 , payload)

else -- no body means removal
	azure.table.delete(
   {account = ACCOUNT, key = KEY, table = 'CacheFun'}
   , pKey, rKey)
end

return ''