mach/lib/multipart/createContent.js

HTTP for JavaScript

"use strict";

/* jshint -W058 */
var Stream = require("bufferedstream");
var Promise = require("../utils/Promise");
var readFile = require("../utils/readFile");
var File = require("../utils/File");

function createHeaders(name, filename, type) {
  var header = "Content-Disposition: form-data; name=\"" + name + "\"";

  if (filename) header += "; filename=\"" + filename + "\"";

  if (type) header += "\r\nContent-Type: " + type;

  return header + "\r\n\r\n";
}

/**
 * Creates and returns a binary stream of multipart content produced
 * from the given params. Param values may be a string, binary, or File
 * object, or an array of any of those types.
 */
function createContent(params, boundary) {
  var content = new Stream();

  // Use a promise chain to write all fields to the content
  // stream in the same order they appear in params.
  var promise = Promise.resolve();

  function appendContent(name, value) {
    if (value instanceof File) {
      var p = readFile(value);

      promise = promise.then(function () {
        content.write("--" + boundary + "\r\n" + createHeaders(name, value.name, value.type));

        return p.then(function (chunk) {
          content.write(chunk);
          content.write("\r\n");
        });
      });
    } else {
      promise = promise.then(function () {
        content.write("--" + boundary + "\r\n" + createHeaders(name));
        content.write(value);
        content.write("\r\n");
      });
    }
  }

  var param, i;
  for (var name in params) {
    if (params.hasOwnProperty(name)) {
      param = params[name];

      if (Array.isArray(param)) {
        for (i = 0, len = param.length; i < len; ++i) appendContent(name, param[i]);
      } else {
        appendContent(name, param);
      }
    }
  }

  promise.then(function () {
    content.end("--" + boundary + "--\r\n");
  }, function (error) {
    content.emit("error", error);
  });

  return content;
}

module.exports = createContent;