Testing ProcessWire repeater behaviour in API use

repeater-test.php

<?php

// Bootstrap ProcessWire                                                                                                                                                                                    
require 'index.php';

// Make sure that FieldtypeRepeater is installed and ready for use                                                                                                                                          
if (!wire('modules')->isInstalled('FieldtypeRepeater')) {
    if (wire('modules')->isInstallable('FieldtypeRepeater')) {
        wire('modules')->install('FieldtypeRepeater');
        echo "Module FieldtypeRepeater installed\n";
    } else {
        throw new WireException("FieldtypeRepeater not installable");
    }
}

// Create repeater field 'repeater' and add it to basic-page template (unless                                                                                                                               
// this field already exists and has been added to said template). The amount                                                                                                                               
// of "boilerplate code" required is interesting; would it make any sense for                                                                                                                               
// repeater fields to automatically create required templates etc.?                                                                                                                                         
$field_name = 'repeater';
$field = wire('fields')->get($field_name);
if (!$field->id) {
    $fieldgroup = new Fieldgroup;
    $fieldgroup->name = "repeater_" . $field_name;
    $fieldgroup->append(wire('fields')->get('title'));
    $fieldgroup->save();
    $template = new Template;
    $template->name = "repeater_" . $field_name;
    $template->fieldgroup = $fieldgroup;
    $template->flags = Template::flagSystem;
    $template->noChildren = 1;
    $template->noParents = 1;
    $template->noGlobal = 1;
    $template->save();
    $field = new Field;
    $field->type = wire('modules')->get('FieldtypeRepeater');
    $field->name = $field_name;
    $field->parent_id = wire('pages')->get("name=for-field-{$field->id}")->id;
    $field->template_id = $template->id;
    $field->save();
    echo substr($field->type, 9) . " field '{$field->name}' added\n";
}
$fieldgroup = wire('fieldgroups')->get('basic-page');
if (!$fieldgroup->hasField($field)) {
    $fieldgroup->add($field);
    $fieldgroup->save();
    echo substr($field->type, 9) . " field '{$field->name}' added to fieldgroup '{$fieldgroup->name}'\n";
}

// Add new page                                                                                                                                                                                             
//                                                                                                                                                                                                          
// Note: if we remove repeater field 'repeater' right after this, repeater page                                                                                                                             
// parent 'for-page-PAGE_ID' will remain in pages table, while repeater parent                                                                                                                              
// 'for-field-FIELD_ID' will be removed. Possible garbage cleaning issue?                                                                                                                                   
$page = new Page;
$page->parent = wire('pages')->get('/');
$template = wire('templates')->get('basic-page');
$page->template = wire('templates')->get('basic-page');
$page->title = "a test page";
$page->save();
echo get_class($page) . " '{$page->url}' added\n";

// Add repeater item                                                                                                                                                                                        
//                                                                                                                                                                                                          
// Note: if we remove repeater field 'repeater' right after this, without first                                                                                                                             
// removing $page, repeater page parent 'for-page-PAGE_ID' will remain in pages                                                                                                                             
// table, while repeater parent 'for-field-FIELD_ID' will be removed. Possible                                                                                                                              
// garbage cleaning issue?                                                                                                                                                                                  
$item = $page->repeater->getNew();
$item->title = "repeater title";
$page->save();
echo get_class($page) . " '{$page->url}' saved\n";

// Delete previously created page                                                                                                                                                                           
//                                                                                                                                                                                                          
// After this repeater page parent 'for-page-PAGE_ID' will be removed, while any                                                                                                                            
// repeater items will remain as orphans in pages table until manually deleted                                                                                                                              
// with direct SQL queries unless we also remove the repeater field. Possible
// garbage cleaning issue?                                                                                                                                                
//                                                                                                                                                                                                          
// It should be noted that such orphan repeater items won't be visible at admin                                                                                                                             
// and attempts to remove repeater field they belong to will results in error:                                                                                                                              
// "Can't delete template 'repeater_repeater' because it is used by 1 pages."                                                                                                                               
$page->delete();
echo get_class($page) . " '{$page->url}' deleted\n";

// Remove repeater field from fieldgroups and then delete the field itself.                                                                                                                                 
//                                                                                                                                                                                                          
// Note: unless we specifically find and delete all items belonging to this                                                                                                                                 
// repeater field (using it's template), the field ends up in a state where                                                                                                                                 
// it can't be removed until remaining repeater items are manually removed                                                                                                                                  
// via database. Not necessarily a real issue, but if possible, preventing                                                                                                                                  
// that would be nice..                                                                                                                                                                                     
$fieldgroups = $field->getFieldgroups();
foreach ($fieldgroups as $fieldgroup) {
    $fieldgroup->remove($field);
    $fieldgroup->save();
    echo substr($field->type, 9) . " field '{$field->name}' removed from fieldgroup '{$fieldgroup->name}'\n";
}
foreach (wire('pages')->find("template=repeater_{$field->name}, include=all") as $page) {
    $page->delete();
    echo get_class($page) . " '{$page->url}' deleted\n";
}
wire('fields')->delete($field);
echo substr($field->type, 9) . " field '{$field->name}' deleted\n";