Lua

Fetch a Chunk of Messages, Tracking Failures

Demonstrates the Chilkat Imap.FetchChunk2 method, which downloads a run of messages by sequence number and reports which succeeded and which failed. The arguments are the starting sequence number, the count, a MessageSet that receives the failed IDs, a MessageSet that receives the successfully-fetched IDs, and the EmailBundle. This example fetches the first chunk of messages and reports the success and failure counts.

Background: When bulk-downloading a large mailbox, individual messages can occasionally fail to fetch (a corrupt message on the server, a transient error) without failing the whole operation. FetchChunk2 is designed for that reality: it returns a partial EmailBundle plus two MessageSet objects so your code can log or retry exactly the messages that did not come through, rather than aborting the entire sync.

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Lua

local chilkat = require("chilkat")

-- Demonstrates the Imap.FetchChunk2 method, which downloads a run of messages by sequence
-- number and reports which succeeded and which failed.  The 1st argument is the starting
-- sequence number, the 2nd is the count, the 3rd receives the failed IDs, the 4th receives
-- the successfully-fetched IDs, and the 5th is the EmailBundle.

local imap = chilkat.Imap.new()

imap.ssl = true
imap.port = 993

local success = imap:connect("imap.example.com")
if not success then
    print(imap.last_error_text)
    return
end

success = imap:login("user@example.com", "myPassword")
if not success then
    print(imap.last_error_text)
    return
end

success = imap:select_mailbox("Inbox")
if not success then
    print(imap.last_error_text)
    return
end

local numMessages = imap.num_messages

-- Fetch messages 1..25 (or fewer if the mailbox is smaller).
local count = 25
if count > numMessages then
    count = numMessages
end

local failedSet = chilkat.MessageSet.new()
local fetchedSet = chilkat.MessageSet.new()
local bundle = chilkat.EmailBundle.new()
success = imap:fetch_chunk2(1, count, failedSet, fetchedSet, bundle)
if not success then
    print(imap.last_error_text)
    return
end

print("Fetched: " .. fetchedSet.count)
print("Failed:  " .. failedSet.count)

success = imap:disconnect()
if not success then
    print(imap.last_error_text)
    return
end