<p><code>BridgeAbstract</code> is a base class for standard bridges. It implements the most common functions to simplify the process of adding new bridges.</p>
<hr/>
<h1><aid="creating-a-new-bridge"href="#creating-a-new-bridge"class="Permalink"aria-hidden="true"title="Permalink">#</a>Creating a new bridge</h1>
<p>You need four basic steps in order to create a new bridge:</p>
<ahref="#step-4---implement-a-function-to-collect-feed-data"><strong>Step 4</strong></a> - Implement a function to collect feed data</p>
<p>These steps are described in more detail below. At the end of this document you’ll find a complete <ahref="#template">template</a> based on these instructions. The pictures below show an example based on these instructions:</p>
<p>Make sure to read these instructions carefully. Please don’t hesitate to open an <ahref="https://github.com/RSS-Bridge/rss-bridge/issues"class="Link--external"rel="noopener noreferrer">Issue</a> if you have further questions (or suggestions). Once your bridge is finished, please open a <ahref="https://github.com/RSS-Bridge/rss-bridge/pulls"class="Link--external"rel="noopener noreferrer">Pull Request</a>, in order to get your bridge merge into RSS-Bridge.</p>
<hr/>
<h2><aid="step-1-create-a-new-file"href="#step-1-create-a-new-file"class="Permalink"aria-hidden="true"title="Permalink">#</a>Step 1 - Create a new file</h2>
<p>Please read <ahref="How_to_create_a_new_bridge.html">these instructions</a> on how to create a new file for RSS-Bridge.</p>
<h2><aid="step-2-add-a-class-extending-bridgeabstract"href="#step-2-add-a-class-extending-bridgeabstract"class="Permalink"aria-hidden="true"title="Permalink">#</a>Step 2 - Add a class, extending <code>BridgeAbstract</code></h2>
<p>Your bridge needs to be a class, which extends <code>BridgeAbstract</code>. The class name must <strong>exactly</strong> match the name of the file, without the file extension.</p>
<h2><aid="step-3-add-general-constants-to-the-class"href="#step-3-add-general-constants-to-the-class"class="Permalink"aria-hidden="true"title="Permalink">#</a>Step 3 - Add general constants to the class</h2>
<p>In order to present your bridge on the front page, RSS-Bridge requires a few constants:</p>
<pre><codeclass="language-PHP">const NAME // Name of the Bridge (default: "Unnamed Bridge")
const URI // URI to the target website of the bridge (default: empty)
const DESCRIPTION // A brief description of the Bridge (default: "No description provided")
const MAINTAINER // Name of the maintainer, i.e. your name on GitHub (default: "No maintainer")
const PARAMETERS // (optional) Definition of additional parameters (default: empty)
const CACHE_TIMEOUT // (optional) Defines the maximum duration for the cache in seconds (default: 3600)
<p><strong>Notice</strong>: <code>const PARAMETERS</code> can be used to request information from the user. Refer to <ahref="#parameters">these instructions</a> for more information.</p>
<h2><aid="step-4-implement-a-function-to-collect-feed-data"href="#step-4-implement-a-function-to-collect-feed-data"class="Permalink"aria-hidden="true"title="Permalink">#</a>Step 4 - Implement a function to collect feed data</h2>
<p>In order for RSS-Bridge to collect data, you must implement the <strong>public</strong> function <code>collectData</code>. This function takes no arguments and returns nothing. It generates a list of feed elements, which must be placed into the variable <code>$this->items</code>.</p>
<p>You can specify additional parameters in order to customize the bridge (i.e. to specify how many items to return). This document explains how to specify those parameters and which options are available to you.</p>
<p>For information on how to read parameter values during execution, please refer to the <ahref="../Helper_functions/index.html#getinput">getInput</a> function.</p>
<hr/>
<h2><aid="adding-parameters-to-a-bridge"href="#adding-parameters-to-a-bridge"class="Permalink"aria-hidden="true"title="Permalink">#</a>Adding parameters to a bridge</h2>
<p>Parameters are specified as part of the bridge class. An empty list of parameters is defined as <code>const PARAMETERS = array();</code></p>
<details><summary>Show example</summary><div>
<pre><codeclass="language-PHP"><?PHP
class MyBridge extends BridgeAbstract {
/* ... */
const PARAMETERS = array(); // Empty list of parameters (can be omitted)
<p>You can also define a set of parameters that will be applied to every possible context of your bridge. To do this, specify a context named <code>global</code>.</p>
<p>Parameters are placed inside a context. They are defined as associative array of parameter specifications. Each parameter is defined by it’s internal input name, a definition in the form <code>'n' => array();</code>, where <code>n</code> is the name with which the bridge can access the parameter during execution.</p>
<p>List values are defined in an associative array where keys are the string displayed in the combo list of the <strong>RSS-Bridge</strong> web interface, and values are the content of the <option> HTML tag value attribute.</p>
<pre><codeclass="language-PHP">...
'type' => 'list',
'values' => array(
'Item A' => 'itemA'
'Item B' => 'itemB'
)
...
</code></pre>
<p>If a more complex organization is required to display the values, the above key/value can be used to set a title as a key and another array as a value:</p>
<p>The queried context is defined via <code>PARAMETERS</code> and can be accessed via <code>$this->queriedContext</code>.
It provides a way to identify which context the bridge is called with.</p>
<p>Example:</p>
<pre><codeclass="language-PHP">...
const PARAMETERS = array(
'By user name' => array(
'u' => array('name' => 'Username')
),
'By user ID' => array(
'id' => array('name' => 'User ID')
)
);
...
</code></pre>
<p>In this example <code>$this->queriedContext</code> will either return <strong>By user name</strong> or <strong>By user ID</strong>. The queried context might return no value, so the best way to handle it is by using a case-structure:</p>
<p>The <code>collectData</code> function is responsible for collecting data and adding items to generate feeds from. If you are unsure how to solve a specific problem, please don’t hesitate to open an <ahref="https://github.com/RSS-Bridge/rss-bridge/issues"class="Link--external"rel="noopener noreferrer">Issue</a> on GitHub. Existing bridges are also a good source to learn implementing your own bridge.</p>
<h2><aid="implementing-the-collectdata-function"href="#implementing-the-collectdata-function"class="Permalink"aria-hidden="true"title="Permalink">#</a>Implementing the <code>collectData</code> function</h2>
<p>Implementation for the <code>collectData</code> function is specific to each bridge. However, there are certain reoccurring elements, described below. RSS-Bridge also provides functions to simplify the process of collecting and parsing HTML data (see “Helper Functions” on the sidebar)</p>
<p>Elements collected by this function must be stored in <code>$this->items</code>. The <code>items</code> variable is an array of item elements, each of which is an associative array that may contain arbitrary keys. RSS-Bridge specifies common keys which are used to generate most common feed formats.</p>
<details><summary>Show example</summary><div>
<pre><codeclass="language-PHP">
$item = array(); // Create a new item
$item['title'] = 'Hello World!';
$this->items[] = $item; // Add item to the list
</code></pre>
</div></details><br>
Additional keys may be added for custom APIs (ignored by RSS-Bridge).
<p>The item array should provide as much information as possible for RSS-Bridge to generate feature rich feeds. Find below list of keys supported by RSS-Bridge.</p>
<pre><codeclass="language-PHP">$item['uri'] // URI to reach the subject ("https://...")
$item['title'] // Title of the item
$item['timestamp'] // Timestamp of the item in numeric or text format (compatible for strtotime())
$item['author'] // Name of the author for this item
$item['content'] // Content in HTML format
$item['enclosures'] // Array of URIs to an attachments (pictures, files, etc...)
$item['categories'] // Array of categories / tags / topics
$item['uid'] // A unique ID to identify the current item
</code></pre>
<p>All formats support these parameters. The formats <code>Plaintext</code> and <code>JSON</code> also support custom parameters.</p>
<p>The <code>getDescription</code> function returns the description for a bridge.</p>
<p><strong>Notice:</strong> By default <strong>RSS-Bridge</strong> returns the contents of <code>const DESCRIPTION</code>, so you only have to implement this function if you require different behavior!</p>
<pre><codeclass="language-PHP"> public function getDescription(){
<p>The <code>getMaintainer</code> function returns the name of the maintainer for a bridge.</p>
<p><strong>Notice:</strong> By default <strong>RSS-Bridge</strong> returns <code>const MAINTAINER</code>, so you only have to implement this function if you require different behavior!</p>
<pre><codeclass="language-PHP"> public function getMaintainer(){
<p>The <code>getName</code> function returns the name of a bridge.</p>
<p><strong>Notice:</strong> By default <strong>RSS-Bridge</strong> returns <code>const NAME</code>, so you only have to implement this function if you require different behavior!</p>
<pre><codeclass="language-PHP"> public function getName(){
<p>The <code>getURI</code> function returns the base URI for a bridge.</p>
<p><strong>Notice:</strong> By default <strong>RSS-Bridge</strong> returns <code>const URI</code>, so you only have to implement this function if you require different behavior!</p>
<pre><codeclass="language-PHP"> public function getURI(){
<p>The <code>getIcon</code> function returns the URI for an icon, used as favicon in feeds.</p>
<p>If no icon is specified by the bridge, RSS-Bridge will use a default location: <code>static::URI . '/favicon.ico'</code> (i.e. “https://github.com/favicon.ico”) which may or may not exist.</p>
<pre><codeclass="language-PHP"> public function getIcon(){
<p>The <code>detectParameters</code> function takes a URL and attempts to extract a valid set of parameters for the current bridge.</p>
<p>If the passed URL is valid for this bridge the function should return an array of parameter -> value pairs that can be used by this bridge, or an empty array if the bridge requires no parameters. If the URL is not relevant for this bridge the function should return <code>null</code>.</p>
<p><strong>Notice:</strong> Implementing this function is optional. By default <strong>RSS-Bridge</strong> tries to match the supplied URL to the <code>URI</code> constant defined in the bridge which may be enough for bridges without any parameters defined.</p>
<pre><codeclass="language-PHP">public function detectParameters($url){
<p><code>BridgeAbstract</code> implements helper methods to make it easier for bridge maintainers to create bridges. Use these methods whenever possible instead of writing your own.</p>
<p>Within the context of the current bridge, stores a value by key in the cache. The value can later be retrieved with <ahref="#loadcachevalue">loadCacheValue</a>.</p>
<p>Within the context of the current bridge, loads a value by key from cache. Optionally specifies the cache duration for the key. Returns <code>null</code> if the key doesn’t exist or the value is expired.</p>
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