Lua Requires Chilkat v11.5.0+

Box: Poll User Events and Save a Checkpoint

See more Box Examples

Poll the authenticated user event stream in bounded batches. The local JSON checkpoint keeps processed event IDs and the next stream position. This single-process demonstration logs events; a production worker should commit its business action, deduplication record, and cursor transactionally and prune old IDs.

See the Box API guide for setup and the complete workflow.

Lua

local chilkat = require("chilkat")

-- Requires Chilkat 11.5.0 or later and a previously unlocked Chilkat bundle.
-- See Global Unlock Sample.
-- Guide: Box API Guide.

local success = false

-- Supply an unexpired token obtained with one of the Box authentication examples.
-- A token represents a particular user or service account. IDs must be accessible to it.
local curl = chilkat.HttpCurl.new()
curl:set_var("access_token", "BOX_ACCESS_TOKEN")

local state = chilkat.JsonObject.new()
local files = chilkat.FileAccess.new()
local statePath = "qa_data/box_events_state.json"
if files:file_exists(statePath) then
    success = state:load_file(statePath)
    if not success then
        print(state.last_error_text)
        return
    end

    if not state:has_member("position") then
        print("Invalid checkpoint: position missing.")
        return
    end
else
    -- "now" starts a new subscription. It deliberately skips historical events.
    state:update_string("position", "now")
end

curl:set_var("position", state:string_of("position"))
local page = chilkat.JsonObject.new()
local seenPath = chilkat.StringBuilder.new()
local eventId = ""
local nextPosition = ""
local batch = 0
local i = 0
local count = 0
local more = true
while (more) and (batch < 20) do
    curl:clear_target_output("*")
    local authorizedCommand1 = chilkat.StringBuilder.new()
    authorizedCommand1:set_string("curl -X GET \"https://api.box.com/2.0/events?stream_type=all&stream_position={{position}}&limit=100\" -H \"Authorization: Bearer {{access_token}}\"")
    local headerReplacement1 = authorizedCommand1:replace("{{access_token}}", curl:get_var("access_token"))
    success = curl:do_your_thing(authorizedCommand1:get_as_string())
    if (not success) or (curl.status_code ~= 200) then
        print("Box request failed. HTTP status: " .. curl.status_code)
        print("Failure reason: " .. curl.fail_reason)
        print(curl.response_body_str)
        return
    end

    success = curl:get_response_json(page)
    if not success then
        print(curl.last_error_text)
        return
    end

    count = page:size_of_array("entries")
    i = 0
    while i < count do
        page.i = i
        eventId = page:string_of("entries[i].event_id")
        if eventId == "" then
            print("Event without an event_id; checkpoint not advanced.")
            return
        end

        seenPath:clear()
        seenPath:append("seen.")
        seenPath:append(eventId)
        if not state:has_member(seenPath:get_as_string()) then
            -- Replace this logging with your idempotent business operation.
            -- Record success only after that operation succeeds.
            print(eventId .. " " .. page:string_of("entries[i].event_type") .. " " .. page:string_of("entries[i].source.id"))
            state:update_bool(seenPath:get_as_string(), true)
        end

        i = i + 1
    end

    nextPosition = page:string_of("next_stream_position")
    if nextPosition == "" then
        print("Missing next_stream_position; checkpoint not advanced.")
        return
    end

    more = (count > 0) and (nextPosition ~= curl:get_var("position"))
    state:update_string("position", nextPosition)
    success = state:write_file(statePath)
    if not success then
        print(state.last_error_text)
        return
    end

    curl:set_var("position", nextPosition)
    batch = batch + 1
end

print("Checkpoint saved. Run again later to continue polling.")