Lua

Fetch an IMAP Attachment into a BinData

Demonstrates the Chilkat Imap.FetchAttachmentBd method, which stores one attachment's bytes in a BinData object. The first argument is the Email, the second is the zero-based attachment index, and the third is the BinData, which is cleared before the operation. This example fetches the first attachment and prints its byte count.

Background: A BinData holds raw bytes, so it works for any attachment type — image, PDF, zip, and so on. From there you can save it, hash it, or hand it to another API expecting a byte buffer, all without touching the filesystem. Use the string/StringBuilder variants only when the attachment is known to be text.

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Lua

local chilkat = require("chilkat")

-- Demonstrates the Imap.FetchAttachmentBd method, which downloads one attachment's bytes into
-- a BinData object.  The 1st argument is the Email, the 2nd is the zero-based attachment
-- index, and the 3rd is the BinData (which is cleared first).
--
-- The message is fetched headers-only, then the attachment is downloaded on demand.

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

-- Fetch only the message headers.  Attachment bodies are NOT downloaded, but the ckx-imap-*
-- metadata describing the attachments is present, so the attachment info methods still work.
local headersOnly = true
local useUid = false
local seqNum = 1
local email = chilkat.Email.new()
success = imap:fetch_email(headersOnly, seqNum, useUid, email)
if not success then
    print(imap.last_error_text)
    return
end

local numAttach = imap:get_mail_num_attach(email)
if numAttach > 0 then
    -- Download just the first attachment's bytes from the server into a BinData.
    local bd = chilkat.BinData.new()
    success = imap:fetch_attachment_bd(email, 0, bd)
    if not success then
        print(imap.last_error_text)
        return
    end

    print("Attachment size: " .. bd.num_bytes .. " bytes")
end

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