This example shows a simple way of performing project-specific actions using the $project_id parameter. NOTE: This particular method is not as clean or as easy to maintain for many projects at once. See the next example for a better way to implement project-specific actions for many projects.

function redcap_save_record($project_id, $record, $instrument, $event_id, $group_id, $survey_hash, $response_id, $repeat_instance)
{
    // Perform certain actions for specific projects (using "switch" or "if" statements).
    switch ($project_id) {

        // Perform operations for project_id 212
        case 212:
            // do something specific for this project ...
            break;

        // Perform operations for project_id 4775
        case 4775:
            // do something specific for this project ...
            break;

        // ...
    }
}

A much more manageable way to perform project-specific operations for many projects at once is to create a directory structure where each project has its own subdirectory under the main Hooks directory (e.g., named "redcap/hooks/pid{$project_id}/redcap_save_record.php"). This allows the code for each project to be sandboxed and separated and also makes it more manageable to utilize other files (e.g., PHP, HTML, CSS, and/or JavaScript files) that you can keep in the project's subdirectory (i.e., "pid{$project_id}") in the Hooks folder. Then the designated project handler PHP script can utilize any of the parameters passed in the function to perform actions specific to each project. NOTE: This example assumes that the "hooks" sub-directory is located in the same directory as the PHP file containing the Hook functions.

function redcap_save_record($project_id, $record, $instrument, $event_id, $group_id, $survey_hash, $response_id, $repeat_instance)
{
    // Set the full path of the project handler PHP script located inside the
    // project-specific sub-folder, which itself exists in the main Hooks folder.
    $project_handler_script = dirname(__FILE__) . "/hooks/pid{$project_id}/redcap_save_record.php";

    // Check if the project handler PHP script exists for this project, and if so,
    // then "include" the script to execute it. If not, do nothing.
    if (file_exists($project_handler_script)) include $project_handler_script;
}

This example provides a simple illustration of how one might email a survey administrator based upon a specific response by a participant.

<?php
// This is a project handler script with filename ...redcap/hooks/pid998/redcap_save_record.php
// This script only gets executed by surveys for project_id 998

// Only perform this action for the survey corresponding to the instrument 'mental_health_survey'
if ($instrument == 'mental_health_survey' && $_POST['suicidal'] == '1' && $response_id != null)
{
    // If the participant just answered "Yes" (1) to the question "Are you suicidal?" (variable "suicidal"),
    // then immediately send an email to the survey administrator so the proper actions may be taken.
    $email_text = "A participant (record '$record') noted on the survey that they are suicidal. "
                . "Please take appropriate actions immediately to contact them.";
    REDCap::email('surveyadmin@mystudy.com', 'redcap@yoursite.edu', 'Suicide alert', $email_text);
}