Creating a zip from a folder full of files can be done in PHP using the ZipArchive class. This class instance creates a handle to read or write files to a compressed archive.

This class includes several properties and methods to zip file archives.

In this article, we will see an example of,

1. How to create a zip archive file.
2. How to download the compressed zip file.

If you want to know how to compress more than one image in PHP image compression refer to this earlier article.

How to create a zip archive file

This file parses the input directory and compresses its files into a zip file. It proceeds with the following steps to create the zip file of a directory.

1. Create a PHP ZipArchive class instance.
2. Open a zip file archive with the instance. It accepts the output zip file name and the mode to open the archive.
3. Apply a recursive parsing in the input directory.
4. If the directory includes a file, then it adds to the zip archive using addFile().

It handles the use cases of getting the possibilities of being unable to read or archive the directory. Once the zip is created, it displays a message to the browser.

create-zip-file.php

<?php

// Important: You should have read and write permissions to read

// the folder and write the zip file

$zipArchive = new ZipArchive();

$zipFile = "./example-zip-file.zip";

if ($zipArchive->open($zipFile, ZipArchive::CREATE) !== TRUE) { exit("Unable to open file.");

}

$folder = 'example-folder/';

createZip($zipArchive, $folder);

$zipArchive->close();

echo 'Zip file created.'; function createZip($zipArchive, $folder)

{ if (is_dir($folder)) { if ($f = opendir($folder)) { while (($file = readdir($f)) !== false) { if (is_file($folder . $file)) { if ($file != '' && $file != '.' && $file != '..') { $zipArchive->addFile($folder . $file); } } else { if (is_dir($folder . $file)) { if ($file != '' && $file != '.' && $file != '..') { $zipArchive->addEmptyDir($folder . $file); $folder = $folder . $file . '/'; createZip($zipArchive, $folder); } } } } closedir($f); } else { exit("Unable to open directory " . $folder); } } else { exit($folder . " is not a directory."); }

}

?>

Output

//If succeeded it returns Zip file created. //If failed it returns Unable to open directory example-folder.
[or] "example-folder is not a director.

How to download the compressed zip file

In the last step, the zip file is created using the PHP ZipArchive class. That zip file can be downloaded by using the PHP code below.

It follows the below steps to download the zip file created.

1. Get the absolute path of the zip file.
2. Set the header parameters like,
   
   • Content length.
   • Content type.
   • Content encoding, and more.

download-zip-file.php

<?php

$filename = "example-zip-file.zip";

if (file_exists($filename)) { // adjust the below absolute file path according to the folder you have downloaded // the zip file // I have downloaded the zip file to the current folder $absoluteFilePath = __DIR__ . '/' . $filename; header('Pragma: public'); header('Expires: 0'); header('Cache-Control: must-revalidate, post-check=0, pre-check=0'); header('Cache-Control: private', false); // content-type has to be defined according to the file extension (filetype) header('Content-Type: application/zip'); header('Content-Disposition: attachment; filename="' . basename($filename) . '";'); header('Content-Transfer-Encoding: binary'); header('Content-Length: ' . filesize($absoluteFilePath)); readfile($absoluteFilePath); exit();

}

?>

This file just has the links to trigger the function to create a zip file containing the compressed archive of the directory. Then, the action to download the output zip archive is called.

index.php

<div class='container'> <h2>Create and Download Zip file using PHP</h2> <p> <a href="create-zip-file.php">Create Zip File</a> </p> <p> <a href="download-zip-file.php">Download Zip File</a> </p>

</div>

Some methods of PHP ZipArchive class

We can do more operations by using the methods and properties of the PHP ZipArchive class. This list of methods is provided by this PHP class.

1. count() – used to get the number of files in the zip archive file.
2. extractTo() – extracts the archive content.
3. renameIndex() – rename a particular archive entry by index.
4. replaceFile() – replace a file in the zip archive with a new file by specifying a new path.

ZipArchive methods used in this example

Some of the methods are used in this example listed below. These are frequently used methods of this class to work with this.

1. open() – Open a zip archive file by specifying the .zip file name.
2. addFile() – To add a file from the input directory to the zip archive.
3. addEmptyDir() – adds an empty directory into the archive to load the subdirectory file of the input directory.
4. close() – closes the active ZipArchive with the reference of the handle.

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Problem Formulation

Challenge: Given a Python list of strings and a query string. Find the strings that partially match the query string.

Example 1:

• Input: ['hello', 'world', 'python'] and 'pyth'
• Output: ['python']

Example 2:

• Input: ['aaa', 'aa', 'a'] and 'a'
• Output: ['aaa', 'aa', 'a']

Example 3:

• Input: ['aaa', 'aa', 'a'] and 'b'
• Output: []

Let’s dive into several methods that solve this and similar type of problems. We start with the most straightforward solution.

Method 1: Membership + List Comprehension

The most Pythonic way to find a list of partial matches of a given string query in a string list lst is to use the membership operator in and the list comprehension statement like so: [s for s in lst if query in s].

Here’s a simple example:

def partial(lst, query): return [s for s in lst if query in s] # Example 1:

print(partial(['hello', 'world', 'python'], 'pyth'))

# ['python'] # Example 2:

print(partial(['aaa', 'aa', 'a'], 'a'))

# ['aaa', 'aa', 'a'] # Example 3:

print(partial(['aaa', 'aa', 'a'], 'b'))

# []

In case you need some background information, feel free to check out our two tutorials and the referenced videos.

Recommended Tutorial: List Comprehension in Python

Recommended Tutorial: The Membership Operator in Python

Method 2: list() and filter()

To find a list of partial query matches given a string list lst, combine the membership operator with the filter() function in which you pass a lambda function that evaluates the membership operation for each element in the list like so: list(filter(lambda x: query in x, lst)).

Here’s an example:

def partial(lst, query): return list(filter(lambda x: query in x, lst)) # Example 1:

print(partial(['hello', 'world', 'python'], 'pyth'))

# ['python'] # Example 2:

print(partial(['aaa', 'aa', 'a'], 'a'))

# ['aaa', 'aa', 'a'] # Example 3:

print(partial(['aaa', 'aa', 'a'], 'b'))

# []

Beautiful Python one-liner, isn’t it?

I recommend you check out the following tutorial with video to shed some light on the background information here:

Recommended Tutorial: Python Filtering

Generally, I like list comprehension more than the filter() function because the former is more concise (e.g., no need to convert the result to a list) and slightly faster. But both work perfectly fine!

Method 3: Regex Match + List Comprehension

The most flexible way to find a list of partial query matches given a string list lst is provided by Python’s powerful regular expressions functionality. For example, the expression [x for x in lst if re.match(pattern, x)] finds all strings that match a certain query pattern as defined by you.

The following examples showcase this solution:

import re def partial(lst, query): pattern = '.*' + query + '.*' return [x for x in lst if re.match(pattern, x)] # Example 1:

print(partial(['hello', 'world', 'python'], 'pyth'))

# ['python'] # Example 2:

print(partial(['aaa', 'aa', 'a'], 'a'))

# ['aaa', 'aa', 'a'] # Example 3:

print(partial(['aaa', 'aa', 'a'], 'b'))

# []

In this example, we use the dummy pattern .*query.* that simply matches words that contain the query string. However, you could also do more advanced pattern matching—regex to the rescue!

Again, I’d recommend you check out the background info on regular expressions:

Recommended Tutorial: Python Regex match() — A Simple Illustrated Guide

Regex Humor

Minimal Error Example

Given the following minimal example where you create a set and attempt to access an element of this set using indexing or slicing:

my_set = {1, 2, 3}

my_set[0]

If you run this code snippet, Python raises the TypeError: 'set' object is not subscriptable:

Traceback (most recent call last): File "C:\Users\xcent\Desktop\code.py", line 2, in <module> my_set[0]

TypeError: 'set' object is not subscriptable

Why Does the Error Occur?

The Python TypeError: 'set' object is not subscriptable occurs if you try to access an element of a set using indexing or slicing that imply an ordering of the set.

However, sets are unordered collections of unique elements: they have no ordering of elements. Thus, you cannot use slicing or indexing, operations that are only possible on an ordered type.

Recommended Tutorial: The Ultimate Guide to Python Sets

How to Fix the Error?

How to fix the TypeError: 'set' object is not subscriptable?

To fix the TypeError: 'set' object is not subscriptable, either convert the unordered set to an ordered list or tuple before accessing it or get rid of the indexing or slicing call altogether.

Here’s an example where you convert the unordered set to an ordered list first. Only then you use indexing or slicing so the error doesn’t occur anymore:

my_set = {1, 2, 3} # Convert set to list:

my_list = list(my_set) # Indexing:

print(my_list[0])

# 1 # Slicing:

print(my_list[:-1])

# [1, 2]

Alternatively, you can also convert the set to a tuple to avoid the TypeError: 'set' object is not subscriptable:

my_tuple = tuple(my_set)

Let’s end this article with a bit of humor, shall we?

Programmer Humor

There are only 10 kinds of people in this world: those who know binary and those who don’t.

~~~

There are 10 types of people in the world. Those who understand trinary, those who don’t, and those who mistake it for binary.