This example illustrates how to perform desired operations for ALL projects, such as displaying static HTML at the bottom of EVERY data entry form.

function redcap_data_entry_form($project_id, $record, $instrument, $event_id, $group_id, $repeat_instance)
{
    print '<div class="yellow">Special announcement text to display at the very bottom
            of every data entry form.</div>';
}

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_data_entry_form($project_id, $record, $instrument, $event_id, $group_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{$project_id}/redcap_data_entry_form.php"). This allows the code for each project to be sandboxed and separated and also makes it more manageable to utilize other files (e.g., PHP, HTML, CSS, and/or JavaScript files) that you can keep in the project's subdirectory (i.e., "pid{$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_data_entry_form($project_id, $record, $instrument, $event_id, $group_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_data_entry_form.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;
}