EDIT

<?php

/**

 * @file

 * Install, update, and uninstall functions for the ext_links module.

 */

/**

 * Implements hook_schema().

 */

function ext_links_schema() {

  $schema['ext_links'] = [

    'description' => 'Table external link templates.',

    'fields' => [

      'id' => [

        'type' => 'varchar',

        'length' => 32,

        'not null' => TRUE,

        'default' => '',

        'description' => 'Name of the ext_link being referenced.',

      ],

      'title' => [

        'type' => 'varchar',

        'length' => 255,

        'not null' => TRUE,

        'description' => 'The link title',

      ],

      'link' => [

        'type' => 'varchar',

        'length' => 2048,

        'not null' => TRUE,

        'description' => 'The link url template',

      ],

      'category' => [

        'type' => 'varchar',

        'length' => 255,

        'description' => 'The link category',

      ],

      'weight' => [

        'type' => 'int',

        'not null' => TRUE,

        'default' => 0,

        'description' => 'Weight of filter within format.',

      ],

      'status' => [

        'type' => 'int',

        'not null' => TRUE,

        'default' => 0,

        'description' => 'External link enabled status. (1 = enabled, 0 = disabled)',

      ],

    ],

    'primary key' => ['id'],

    'indexes' => [

      'list' => ['weight', 'id'],

    ],

  ];

  return $schema;

}

/**

 * implements hook_install()

 */

function ext_links_install() {

  $links_templates = migrate_old_ext_links();

  foreach ($links_templates as $ext_link){

    db_delete('variable')

      ->condition('name', "ext_links_" . $ext_link->id . '_%', 'LIKE')

      ->execute();

  }

  variable_set('ext_links_appearance_grouped', variable_get('ext_links_options', 0) != 1 ? 1 : 0 );

  variable_del('ext_links_options');

}

/**

 * Implements hook_uninstall().

 */

function ext_links_uninstall() {

  db_drop_table('ext_links');

}

/**

 * Update function to migrate previous versions

 */

function ext_links_update_7001(){

    $connection_info = Database::parseConnectionInfo();

    $db_prefix = $connection_info['default']['default']['prefix'];

    foreach(ext_links_schema() as $table_name => $schema){

      if(!db_table_exists($db_prefix . $table_name)){

        db_create_table($db_prefix . $table_name, $schema);

      }

    }

    ext_links_install();

    return "ext_links table created and old settings migrated.";

}

/**

 * Update ext_link to cdm_tokens functionality

 */

function ext_links_update_7002(){

  $tasks_performed = [];

  module_enable(['cdm_tokens'], TRUE);

  $tasks_performed[] = "cdm_tokens module enabled.";

  $column_glue_exists = db_query("SHOW COLUMNS FROM {ext_links} LIKE 'glue';")->rowCount();

  if($column_glue_exists){

    db_query("ALTER TABLE {ext_links} DROP COLUMN glue;");

    $tasks_performed[] = "ext_links table: Column glue removed.";

  }

  db_query("ALTER TABLE {ext_links} MODIFY COLUMN link varchar(2048) NOT NULL COMMENT 'The link url template';");

  $tasks_performed[] = "ext_links.link modified to varchar 2048.";

  ext_links_template_links_update();

  $tasks_performed[] = "ext_link template links updated.";

  $block_info = ext_links_block_info();

  db_update("block")

    ->fields([

      'pages' => $block_info['0']['pages'],

      'visibility' => 1

    ])

    ->condition('module', 'ext_links')

    ->execute();

  $tasks_performed[] = "ext_links block configuration updated.";

  return join("; \n", $tasks_performed);

}

/**

 * - remove link to ePIC

 * - set improved ulr for the wfo link

 */

function ext_links_update_7003() {

  $tasks_performed = [];

  $links_templates = ext_links_templates();

  if(array_key_exists('epic', $links_templates)) {

    db_delete('ext_links')->condition('id', 'epic')->execute();

    $tasks_performed[] = "ext_link for ePIC removed";

  }

  if(array_key_exists('wfo', $links_templates)) {

    $defaults = ext_links_template_defaults();

    db_update('ext_links')->fields(array(

      'link' => $defaults['wfo']['link']

    ))->condition('id', 'wfo')

      ->execute();

    $tasks_performed[] = "set improved URL for the wfo external link";

  }

  return join("; \n", $tasks_performed);

}

/**

 * Migrates old ext link templates from drupal vars to the ext_link table.

 */

function migrate_old_ext_links(){

  $links_templates = ext_links_templates();

  foreach ($links_templates as $ext_link){

    $ext_link = _ext_links_merge_old_vars($ext_link);

    ext_links_save($ext_link);

  }

  return $links_templates;

}

/**

 * Updates the ext_links.link column with new urls from the default templates.

 */

function ext_links_template_links_update(){

  $template_default_arrays = ext_links_template_defaults();

  foreach ($template_default_arrays as $template_array) {

    $return = db_merge('ext_links')

      ->key(['id' => $template_array['id']])

      ->fields([

        'link' => $template_array['link'],

        'title' => $template_array['title'],

      ])

      ->execute();

  }

}

/**

 * Merge the old settings stored in drupal vars into the ext_link template object

 * @param $ext_link object

 *

 * @return object

 *  The ext link template

 */

function _ext_links_merge_old_vars($ext_link){

  $ext_link_id = $ext_link->id;

  $ext_link->status = variable_get("ext_links_${ext_link_id}_check", $ext_link->status);

  $ext_link->link =  variable_get("ext_links_${ext_link_id}_link", $ext_link->link);

  $ext_link->title = variable_get("ext_links_${ext_link_id}_text", $ext_link->title);

  return $ext_link;

}