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--- hello_world_plugin_extended [2017/01/22 20:53]
lokothodida
+++ hello_world_plugin_extended [2017/01/22 21:21]
lokothodida [hello_world/common_functions.php]
@@ Line 124: / Line 124: @@
 ===== hello_world/common_functions.php =====
+The first functions that we need to define are ''hello_world_i18n'' (''i18n'' alias), ''hello_world_admin'' (displays the administration panel) and ''hello_world_footer'' (echoes the message into the theme footer). The latter two will just be stubs that get filled in later:
+<code php>
+// Alias for getting i18n strings for this plugin
+function hello_world_i18n($key) {
+  return i18n_r(HELLO_WORLD . '/' . $key);
+}
+// Administration panel
+function hello_world_admin() {
+  // ...
+}
+// Hook for the theme footer
+function hello_world_footer() {
+  // ...
+}
+</code>
+Now consider the operations that we want to have for the plugin data. The administrator will be able to create a custom message, save it, and then this message will be printed in the theme footer. So we shall create functions for saving this message into a file the ''data/other'' folder. To future-proof this plugin, we will save the data as ''key=>value'' pairs, so the message will be a value with a designated key (ideally the key ''message''):
+<code php>
+// Given an array of key=>value mappings, save that data to the configuration file
+function hello_world_save_config($config = array()) {
+  $file     = HELLO_WORLD_CONFIGFILE;
+  $contents = json_encode($config);            // Encodes the array into a valid JSON string
+  return file_put_contents($file, $contents);  // Saves the JSON string into the configuration JSON file
+}
+// Load plugin configuration from the JSON file as an array
+function hello_world_get_config() {
+  $file     = HELLO_WORLD_CONFIGFILE;
+  $contents = file_get_contents($file);
+  $json     = json_decode($contents);    // Decodes the string
+  $config   = (array) $json;             // Converts the object into a PHP array
+  return $config;
+}
+</code>
+When the plugin is first loaded, the configuration file might not exist. So let's create some utility functions that detect if the file exists, and which create some default data:
+<code php>
+// Check that the configuration file exists
+function hello_world_config_exists() {
+  return file_exists(HELLO_WORLD_CONFIGFILE);
+}
+// Create a default configuration file
+function hello_world_init() {
+  $config = array('message' => hello_world_i18n('HELLO_WORLD'));
+  return hello_world_save_config($config);
+}
+</code>
+Now we can expand on the administration panel. First we ensure that the configuration file exists:
+<code php>
+// Administration panel
+function hello_world_admin() {
+  // Initialize the configuration file
+  $init = hello_world_config_exists() || hello_world_init();
+  // ...
+}
+</code>
+Then we will load the configuration data, and load the ''admin.php'' file (which will use this data and display the admin panel):
+<code php>
+// Administration panel
+function hello_world_admin() {
+  // Initialize the configuration file
+  $init = hello_world_config_exists() || hello_world_init();
+  // still more to add...
+  // Show the admin panel page
+  $config = hello_world_get_config();
+  include(HELLO_WORLD_PLUGINPATH . '/admin.php');
+}
+</code>
+The admin panel will have a ''<form>'' whose method is ''POST'' and whose action is simply the same page. There will be a text field with the name ''message'', and the submit button in said form will have the name ''save-configuration''. So if we want to save the configuration, we will need to check if the ''$_POST'' variable is populated with the ''save-configuration'' key:
+<code php>
+function hello_world_admin() {
+  // Initialize the configuration file
+  $init = hello_world_config_exists() || hello_world_init();
+  // Check if we need to save the configuration
+  $save_changes = isset($_POST['save-configuration']);
+  if ($save_changes) {
+    $save_success = hello_world_save_config($data);
+  }
+  // Show the admin panel page
+  $config = hello_world_get_config();
+  include(HELLO_WORLD_PLUGINPATH . '/admin.php');
+}
+</code>
+Lastly, we need the footer hook to actually load the message:
+<code php>
+// Hook for the theme footer
+function hello_world_footer() {
+  $config = hello_world_get_config();
+  echo '<p>' . $config['message'] . '</p>';
+}
+</code>
+This is the full file. It slightly expands on the administration panel by printing error messages and a introducing a placeholder for validating the submitted data:
 <file php common_functions.php>
 <?php

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