React Native

Add a Content-Length Header to MIME

Demonstrates the Chilkat Mime.AddContentLength method, which computes the byte length of the entity's serialized body and adds or updates its Content-Length header. It takes no arguments and is a void method. The count is based on the transfer-encoded serialized body.

Note: The file path is relative to the application's current working directory. Absolute paths may also be used. Supply the path to your own file.

Background: Some protocols and consumers want a Content-Length declaring the body size up front. This computes it correctly from the encoded body — the bytes actually written — rather than the decoded content, and updates any existing header so it stays accurate. Call it after the body is final; if you change the body afterward, call it again, or remove the header, since a stale length is worse than none.

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React Native

import { Mime } from '@chilkat/react-native'

function chilkatExample() {
  const mime = new Mime();
  try {
    mime.loadMimeFile('qa_data/message.eml');
  } catch {
    console.log(mime.lastErrorText);
    return;
  }

  // Compute the byte length of the entity's serialized body and add (or update) its Content-Length
  // header.  The count is based on the transfer-encoded serialized body.  It is a void method.
  mime.addContentLength();

  let contentLength: string;
  try {
    contentLength = mime.getHeaderField('Content-Length');
  } catch {
    console.log(mime.lastErrorText);
    return;
  }

  console.log(`Content-Length: ${contentLength}`);
}