1 Friendica Storage Backend Addon development
2 ===========================================
6 Storage backends can be added via addons.
7 A storage backend is implemented as a class, and the plugin register the class to make it avaiable to the system.
9 ## The Storage Backend Class
11 The class must live in `Friendica\Addon\youraddonname` namespace, where `youraddonname` the folder name of your addon.
13 The class must implement `Friendica\Model\Storage\IStorage` interface. All method in the interface must be implemented:
15 namespace Friendica\Model\Storage;
20 public function get(string $reference);
21 public function put(string $data, string $reference = '');
22 public function delete(string $reference);
23 public function getOptions();
24 public function saveOptions(array $data);
25 public function __toString();
26 public static function getName();
30 - `get(string $reference)` returns data pointed by `$reference`
31 - `put(string $data, string $reference)` saves data in `$data` to position `$reference`, or a new position if `$reference` is empty.
32 - `delete(string $reference)` delete data pointed by `$reference`
34 Each storage backend can have options the admin can set in admin page.
36 - `getOptions()` returns an array with details about each option to build the interface.
37 - `saveOptions(array $data)` get `$data` from admin page, validate it and save it.
39 The array returned by `getOptions()` is defined as:
42 'option1name' => [ ..info.. ],
43 'option2name' => [ ..info.. ],
47 An empty array can be returned if backend doesn't have any options.
49 The info array for each option is defined as:
54 define the field used in form, and the type of data.
55 one of 'checkbox', 'combobox', 'custom', 'datetime', 'input', 'intcheckbox', 'password', 'radio', 'richtext', 'select', 'select_raw', 'textarea'
59 Translatable label of the field. This label will be shown in admin page
63 Current value of the option
67 Translatable description for the field. Will be shown in admin page
71 Optional. Depends on which 'type' this option is:
73 - 'select': array `[ value => label ]` of choices
74 - 'intcheckbox': value of input element
75 - 'select_raw': prebuild html string of `<option >` tags
76 - 'yesno': array `[ 'label no', 'label yes']`
78 Each label should be translatable
83 See doxygen documentation of `IStorage` interface for details about each method.
85 ## Register a storage backend class
87 Each backend must be registered in the system when the plugin is installed, to be aviable.
89 `DI::facStorage()->register(string $class)` is used to register the backend class.
91 When the plugin is uninstalled, registered backends must be unregistered using
92 `DI::facStorage()->unregister(string $class)`.
94 You have to register a new hook in your addon, listening on `storage_instance(App $a, array $data)`.
95 In case `$data['name']` is your storage class name, you have to instance a new instance of your `Friendica\Model\Storage\IStorage` class.
96 Set the instance of your class as `$data['storage']` to pass it back to the backend.
98 This is necessary because it isn't always clear, if you need further construction arguments.
102 **Currently testing is limited to core Friendica only, this shows theoretically how tests should work in the future**
104 Each new Storage class should be added to the test-environment at [Storage Tests](https://github.com/friendica/friendica/tree/develop/tests/src/Model/Storage/).
106 Add a new test class which's naming convention is `StorageClassTest`, which extend the `StorageTest` in the same directory.
108 Override the two necessary instances:
110 use Friendica\Model\Storage\IStorage;
112 abstract class StorageTest
114 // returns an instance of your newly created storage class
115 abstract protected function getInstance();
117 // Assertion for the option array you return for your new StorageClass
118 abstract protected function assertOption(IStorage $storage);
124 Here an hypotetical addon which register an unusefull storage backend.
125 Let's call it `samplestorage`.
127 This backend will discard all data we try to save and will return always the same image when we ask for some data.
128 The image returned can be set by the administrator in admin page.
130 First, the backend class.
131 The file will be `addon/samplestorage/SampleStorageBackend.php`:
135 namespace Friendica\Addon\samplestorage;
137 use Friendica\Model\Storage\IStorage;
139 use Friendica\Core\Config\IConfig;
140 use Friendica\Core\L10n;
142 class SampleStorageBackend implements IStorage
144 const NAME = 'Sample Storage';
152 * SampleStorageBackend constructor.
153 * @param IConfig $config The configuration of Friendica
155 * You can add here every dynamic class as dependency you like and add them to a private field
156 * Friendica automatically creates these classes and passes them as argument to the constructor
158 public function __construct(IConfig $config, L10n $l10n)
160 $this->config = $config;
164 public function get(string $reference)
166 // we return always the same image data. Which file we load is defined by
168 $filename = $this->config->get('storage', 'samplestorage', 'sample.jpg');
169 return file_get_contents($filename);
172 public function put(string $data, string $reference = '')
174 if ($reference === '') {
175 $reference = 'sample';
177 // we don't save $data !
181 public function delete(string $reference)
183 // we pretend to delete the data
187 public function getOptions()
189 $filename = $this->config->get('storage', 'samplestorage', 'sample.jpg');
192 'input', // will use a simple text input
193 $this->l10n->t('The file to return'), // the label
194 $filename, // the current value
195 $this->l10n->t('Enter the path to a file'), // the help text
196 // no extra data for 'input' type..
201 public function saveOptions(array $data)
203 // the keys in $data are the same keys we defined in getOptions()
204 $newfilename = trim($data['filename']);
206 // this function should always validate the data.
207 // in this example we check if file exists
208 if (!file_exists($newfilename)) {
209 // in case of error we return an array with
210 // ['optionname' => 'error message']
211 return ['filename' => 'The file doesn\'t exists'];
214 $this->config->set('storage', 'samplestorage', $newfilename);
216 // no errors, return empty array
220 public function __toString()
225 public static function getName()
232 Now the plugin main file. Here we register and unregister the backend class.
234 The file is `addon/samplestorage/samplestorage.php`
239 * Name: Sample Storage Addon
240 * Description: A sample addon which implements an unusefull storage backend
242 * Author: Alice <https://alice.social/~alice>
245 use Friendica\Addon\samplestorage\SampleStorageBackend;
248 function samplestorage_install()
250 // on addon install, we register our class with name "Sample Storage".
251 // note: we use `::class` property, which returns full class name as string
252 // this save us the problem of correctly escape backslashes in class name
253 DI::storageManager()->register(SampleStorageBackend::class);
256 function samplestorage_unistall()
258 // when the plugin is uninstalled, we unregister the backend.
259 DI::storageManager()->unregister(SampleStorageBackend::class);
262 function samplestorage_storage_instance(\Friendica\App $a, array $data)
264 if ($data['name'] === SampleStorageBackend::getName()) {
265 // instance a new sample storage instance and pass it back to the core for usage
266 $data['storage'] = new SampleStorageBackend(DI::config(), DI::l10n(), DI::cache());
271 **Theoretically - until tests for Addons are enabled too - create a test class with the name `addon/tests/SampleStorageTest.php`:
274 use Friendica\Model\Storage\IStorage;
275 use Friendica\Test\src\Model\Storage\StorageTest;
277 class SampleStorageTest extends StorageTest
279 // returns an instance of your newly created storage class
280 protected function getInstance()
282 // create a new SampleStorageBackend instance with all it's dependencies
283 // Have a look at DatabaseStorageTest or FilesystemStorageTest for further insights
284 return new SampleStorageBackend();
287 // Assertion for the option array you return for your new StorageClass
288 protected function assertOption(IStorage $storage)
290 $this->assertEquals([
293 'The file to return',
295 'Enter the path to a file'
297 ], $storage->getOptions());