React Native

Fetch a Text IMAP Attachment as a String

Demonstrates the Chilkat Imap.FetchAttachmentString method, which returns one text attachment decoded to a string. The first argument is the Email, the second is the zero-based attachment index, and the third is the charset used to decode the bytes. This example returns the first attachment as a UTF-8 string.

Background: This is the convenient form when you simply want a small text attachment's content inline as a string. Only use it for attachments known to be text; decoding binary content through a charset can alter or corrupt the bytes. For binary data use FetchAttachmentBd, and for large text a StringBuilder (via FetchAttachmentSb) avoids an extra copy.

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React Native

import { Email, Imap } from '@chilkat/react-native'

async function chilkatExample() {
  // Demonstrates the Imap.FetchAttachmentString method, which downloads one text attachment and
  // returns it decoded to a string.  The 1st argument is the Email, the 2nd is the zero-based
  // attachment index, and the 3rd is the charset used to decode the bytes.
  // 
  // The message is fetched headers-only, then the attachment is downloaded on demand.

  const imap = new Imap();

  imap.ssl = true;
  imap.port = 993;

  try {
    await imap.connectAsync('imap.example.com');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  try {
    await imap.loginAsync('user@example.com', 'myPassword');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  try {
    await imap.selectMailboxAsync('Inbox');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  // 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.
  const headersOnly = true;
  const useUid = false;
  const seqNum = 1;
  const email = new Email();
  try {
    await imap.fetchEmailAsync(headersOnly, seqNum, useUid, email);
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  const numAttach = imap.getMailNumAttach(email);
  if (numAttach > 0) {
    // FetchAttachmentString returns a string, so assign it to a string variable.
    let attachText: string;
    try {
      attachText = await imap.fetchAttachmentStringAsync(email, 0, 'utf-8');
    } catch {
      console.log(imap.lastErrorText);
      return;
    }

    console.log(attachText);
  }

  try {
    await imap.disconnectAsync();
  } catch {
    console.log(imap.lastErrorText);
    return;
  }
}