Coding Style & General Guidelines


  • Ideally, discuss your plans on the mailing list to see if others want to work with you on it
  • We use Github, please get an account there and clone the repositories you want to work on
  • Fixes go directly to master, nevertheless they need to be tested thoroughly.
  • New features are always developed in a branch and only merged to master once they are fully done.
  • Software should work. We only put features into master when they are complete. It’s better to not have a feature instead of having one that works poorly.
  • It is best to start working based on an issue - create one if there is none. You describe what you want to do, ask feedback on the direction you take it and take it from there.
  • When you are finished, use the merge request function on Github to create a pull request. The other developers will look at it and give you feedback. You can signify that your PR is ready for review by adding the label “5 - ready for review” to it. You can also post your merge request to the mailing list to let people know. See the code review page for more information
  • It is key to keep changes separate and small. The bigger and more hairy a PR grows, the harder it is to get it in. So split things up where you can in smaller changes - if you need a small improvement like a API addition for a big feature addition, get it in first rather than adding it to the big piece of work!
  • Decisions are made by consensus. We strive for making the best technical decisions and as nobody can know everything, we collaborate. That means a first negative comment might not be the final word, neither is positive feedback an immediate GO. ownCloud is built out of modular pieces (apps) and maintainers have a strong influence. In case of disagreement we consult other seasoned contributors.
  • We need a signed contributor agreement from you to commit into the core repository (apps don’t need that). All the information is in our Contributor agreement FAQ.


We assign labels to issues and pull requests to make it easy to find them and to signal what needs to be done. Some of these are assigned by the developers, others by QA, bug triagers, project lead or maintainers and so on. It is not desired that users/reporters of bugs assign labels themselves, unless they are developers/contributors to ownCloud.

The most important labels and their meaning:

  • #bug - this issue is a bug
  • #enhancement - this issue is a feature request/idea for improvement of ownCloud
  • #design - this needs help from the design team or is a design-related issue/pull request
  • #sharing - this issue or PR is related to sharing
  • #technical debt - this issue or PR is about technical debt
  • #sev1-critical #sev2-high #sev3-medium #sev4-low signify how important the bug is.
  • #p1-urgent #p2-high #p3-medium #p4-low signify the priority of the bug.
  • #Junior Job - these are issues which are relatively easy to solve and ideal for people who want to learn how to code in ownCloud
  • Tags showing the state of the issue or PR, numbered 1-6:
  • #1 - To develop - ready to start development on this
  • #2 - Developing - development in progress
  • #3 - To Review - ready for review
  • #4 - To Release - reviewed PR that awaits unfreeze of a branch to get merged
  • App tags: #app:files #app:user_ldap #app:files_versions and so on. These tags indicate the app that is impacted by the issue or which the PR is related to
  • Settings tags: #settings:personal #settings:apps #settings:admin and so on. These tags indicate the settings area that is impacted by the issue or which the PR is related to
  • db tags: #db:mysql #db:sqlite #db:postgresql and so on. These tags indicate the database that is impacted by the issue or which the PR is related to
  • Browser tags: #browser:ie #browser:safari and so on. These tags indicate the browser that is impacted by the issue or which the PR is related to
  • Component tags: #comp:filesystem #comp:javascript and so on. These tags indicate the components of ownCloud impacted by the issue or which the PR is related to
  • Development tool tags: #dev:unit_testing #dev:public_API and so on. These tags indicate development-specific tools like those for testing and public developer-facing API’s impacted by the issue or which the PR is related
  • Feature tags: #feature:something. These tags indicate the features across apps and components which are impacted by the issue or which the PR is related to
  • #triage - this issue has to be triaged
  • #needs info - this issue needs further information from the reporter, see triaging old tag is #clarification request, please don’t use that one anymore.
  • #discussion - this issue needs to be discussed
  • #security - this is a security related issue
  • #windows server - this is related to windows server
  • #research - this item requires some research before it can continue
  • #packaging - this is related to packaging
  • #theming - refers to theming issues or improvements
  • #l10n - refers to translation issues or improvements
  • #release note - relevant for the release notes
  • #privacy - refers to issues that might lead to privacy concerns
  • #won’t fix - This problem won’t be fixed (can be for a wide variety of reasons...)

Severity Level Labels

To better understand which severity level to apply, if any, here is a description of each of the four respective labels.

Label Description
#sev1-critical The operation is in production and is mission critical to the business. The product is inoperable and the situation is resulting in a total disruption of work. There is no workaround available.
#sev2-high Operations are severely restricted. Important features are unavailable, although work can continue in a limited fashion. A workaround is available.
#sev3-medium The product does not work as designed resulting in a minor loss of usage. A workaround is available.
#sev4-low There is no loss of service. This may be a request for documentation, general information, product enhancement request, etc.

Don’t See The Label You Need?

If you want a label not in the list above, please first discuss on the mailing list.


  • Maximum line-length of 80 characters
  • Use tabs to indent
  • A tab is 4 spaces wide
  • Opening braces of blocks are on the same line as the definition
  • Quotes: ‘ for everything, ” for HTML attributes (<p class=”my_class”>)
  • End of Lines : Unix style (LF / ‘n’) only
  • No global variables or functions
  • Unit tests
  • HTML should be HTML5 compliant
  • Check these database performance tips
  • When you git pull, always git pull --rebase to avoid generating extra commits like: merged master into master

User interface

  • Software should get out of the way. Do things automatically instead of offering configuration options.
  • Software should be easy to use. Show only the most important elements. Secondary elements only on hover or via Advanced function.
  • User data is sacred. Provide undo instead of asking for confirmation - which might be dismissed
  • The state of the application should be clear. If something loads, provide feedback.
  • Do not adapt broken concepts (for example design of desktop apps) just for the sake of consistency. We aim to provide a better interface, so let’s find out how to do that!
  • Regularly reset your installation to see how the first-run experience is like. And improve it.
  • Ideally do usability testing to know how people use the software.
  • For further UX principles, read Alex Faaborg from Mozilla.


The ownCloud coding style guide is based on PEAR Coding Standards.

Always use:


at the start of your php code. The final closing:


should not be used at the end of the file due to the possible issue of sending white spaces.


All API methods need to be marked with PHPDoc markup. An example would be:


 * Description what method does
 * @param Controller $controller the controller that will be transformed
 * @param API $api an instance of the API class
 * @throws APIException if the api is broken
 * @since 4.5
 * @return string a name of a user
public function myMethod(Controller $controller, API $api) {
  // ...

Objects, Functions, Arrays & Variables

Use Pascal case for Objects, Camel case for functions and variables. If you set a default function/method parameter, do not use spaces. Do not prepend private class members with underscores.

class MyClass {


function myFunction($default=null) {


$myVariable = 'blue';

$someArray = array(
    'foo'  => 'bar',
    'spam' => 'ham',



Use === and !== instead of == and !=.

Here’s why:


var_dump(0 == "a"); // 0 == 0 -> true
var_dump("1" == "01"); // 1 == 1 -> true
var_dump("10" == "1e1"); // 10 == 10 -> true
var_dump(100 == "1e2"); // 100 == 100 -> true


Control Structures

  • Always use { } for one line ifs
  • Split long ifs into multiple lines
  • Always use break in switch statements and prevent a default block with warnings if it shouldn’t be accessed

// single line if
if ($myVar === 'hi') {
    $myVar = 'ho';
} else {
    $myVar = 'bye';

// long ifs
if (   $something === 'something'
    || $condition2
    && $condition3
) {
  // your code

// for loop
for ($i = 0; $i < 4; $i++) {
    // your code

switch ($condition) {
    case 1:
        // action1

    case 2:
        // action2;

        // defaultaction;


Unit tests

Unit tests must always extend the \Test\TestCase class, which takes care of cleaning up the installation after the test.

If a test is run with multiple different values, a data provider must be used. The name of the data provider method must not start with test and must end with Data.

namespace Test;
class Dummy extends \Test\TestCase {
    public function dummyData() {
        return array(
            array(1, true),
            array(2, false),

     * @dataProvider dummyData
    public function testDummy($input, $expected) {
        $this->assertEquals($expected, \Dummy::method($input));


In general take a look at JSLint without the whitespace rules.

  • Use a js/main.js or js/app.js where your program is started
  • Complete every statement with a ;
  • Use var to limit variable to local scope
  • To keep your code local, wrap everything in a self executing function. To access global objects or export things to the global namespace, pass all global objects to the self executing function.
  • Use JavaScript strict mode
  • Use a global namespace object where you bind publicly used functions and objects to


// set up namespace for sharing across multiple files
var MyApp = MyApp || {};

(function(window, $, exports, undefined) {
    'use strict';

    // if this function or object should be global, attach it to the namespace
    exports.myGlobalFunction = function(params) {
        return params;

})(window, jQuery, MyApp);

DONT (Seriously):

// This does not only make everything global but you're programming
// JavaScript like C functions with namespaces
MyApp = {
    myFunction:function(params) {
        return params;

Objects & Inheritance

Try to use OOP in your JavaScript to make your code reusable and flexible.

This is how you’d do inheritance in JavaScript:

// create parent object and bind methods to it
var ParentObject = function(name) { = name;

ParentObject.prototype.sayHello = function() {

// create childobject, call parents constructor and inherit methods
var ChildObject = function(name, age) {, name);
    this.age = age;

ChildObject.prototype = Object.create(ParentObject.prototype);

// overwrite parent method
ChildObject.prototype.sayHello = function() {
    // call parent method if you want to;

var child = new ChildObject('toni', 23);

// prints:
// toni
// childobject

Objects, Functions & Variables

Use Pascal case for Objects, Camel case for functions and variables.

var MyObject = function() {
    this.attr = "hi";

var myFunction = function() {
    return true;

var myVariable = 'blue';

var objectLiteral = {
    value1: 'somevalue'


Use === and !== instead of == and !=.

Here’s why:

'' == '0'           // false
0 == ''             // true
0 == '0'            // true

false == 'false'    // false
false == '0'        // true

false == undefined  // false
false == null       // false
null == undefined   // true

' \t\r\n ' == 0     // true

Control Structures

  • Always use { } for one line ifs
  • Split long ifs into multiple lines
  • Always use break in switch statements and prevent a default block with warnings if it shouldn’t be accessed


// single line if
if (myVar === 'hi') {
    myVar = 'ho';
} else {
    myVar = 'bye';

// long ifs
if (   something === 'something'
    || condition2
    && condition3
) {
  // your code

// for loop
for (var i = 0; i < 4; i++) {
    // your code

// switch
switch (value) {

    case 'hi':
        // yourcode

        console.warn('Entered undefined default block in switch');


Take a look at the Writing Tactical CSS & HTML video on YouTube.

Don’t bind your CSS too much to your HTML structure and try to avoid IDs. Also try to make your CSS reusable by grouping common attributes into classes.


.list {
    list-style-type: none;

.list > .list_item {
    display: inline-block;

.important_list_item {
    color: red;


#content .myHeader ul {
    list-style-type: none;

#content .myHeader ul li.list_item {
    color: red;
    display: inline-block;


All documentation licensed under the Creative Commons Attribution 3.0 Unported license.