read_zip.md

---

title: "How to read a file" layout: default

section: example

This page explains how to read an existing zip file or add a existing file into the zip file.

In the browser

AJAX request

Getting binary data with an ajax request is hard (mainly because of IE <= 9). The easy way is to use PizZipUtils.getBinaryContent. With PizZipUtils.getBinaryContent, you can do the following (see the documentation for more examples) :

PizZipUtils.getBinaryContent("path/to/content.zip", function (err, data) {
  if (err) {
    throw err; // or handle err
  }

  var zip = new PizZip(data);
});

If you need to adapt an existing solution to what getBinaryContent does, here are the details. When doing a XHR request (level 1, without setting the responseType) the browser will try to interpret the response as a string and decode it from its charset. To avoid this on Firefox/Chrome/Opera, you need to set mime type : xhr.overrideMimeType("text/plain; charset=x-user-defined");. On IE <= 9, this is harder. The overrideMimeType trick doesn't work so we need to use vbscript and non standard attributes. On IE > 9, overrideMimeType doesn't work but xhr2 does.

With xhr 2, you can just set the responseType attribute : xhr.responseType = "arraybuffer";. With this, the browser will return an ArrayBuffer.

Local files

If the browser supports the FileReader API, you can use it to read a zip file. PizZip can read ArrayBuffer, so you can use FileReader.readAsArrayBuffer(Blob), see this example.

In nodejs

PizZip can read Buffers so you can do the following :

Local file

"use strict";

var fs = require("fs");
var PizZip = require("pizzip");

// read a zip file
fs.readFile("test.zip", function (err, data) {
  if (err) throw err;
  var zip = new PizZip(data);
});

// read a file and add it to a zip
fs.readFile("picture.png", function (err, data) {
  if (err) throw err;
  var zip = new PizZip();
  zip.file("picture.png", data);
});

Remote file

There are a lot of nodejs libraries doing http requests, from the built-in http to the npm packages. Here are two examples, one with the default http API, the other with request (but you're free to use your favorite library !). If possible, download the file as a Buffer (you will get better performances). If it's not possible, you can fallback to a binary string (the option is likely to be encoding : "binary").

With http :

"use strict";

var http = require("http");
var url = require("url");
var PizZip = require("pizzip");

var req = http.get(url.parse("http://localhost/.../file.zip"), function (res) {
  if (res.statusCode !== 200) {
    console.log(res.statusCode);
    // handle error
    return;
  }
  var data = [],
    dataLen = 0;

  // don't set the encoding, it will break everything !
  // or, if you must, set it to null. In that case the chunk will be a string.

  res.on("data", function (chunk) {
    data.push(chunk);
    dataLen += chunk.length;
  });

  res.on("end", function () {
    var buf = Buffer.alloc(dataLen);
    for (var i = 0, len = data.length, pos = 0; i < len; i++) {
      data[i].copy(buf, pos);
      pos += data[i].length;
    }

    // here we go !
    var zip = new PizZip(buf);
    console.log(zip.file("content.txt").asText());
  });
});

req.on("error", function (err) {
  // handle error
});

With request :

"use strict";

var request = require("request");
var PizZip = require("pizzip");

request(
  {
    method: "GET",
    url: "http://localhost/.../file.zip",
    encoding: null, // <- this one is important !
  },
  function (error, response, body) {
    if (error || response.statusCode !== 200) {
      // handle error
      return;
    }
    var zip = new PizZip(body);
    console.log(zip.file("content.txt").asText());
  }
);