Campaign::subscribe() fails when $isModel=true — Orm\Builder is not iterable

[ryu3k]

Bug Description

Campaign::subscribe() silently returns 0 results when called with $isModel = true and a Builder object (as done by subscribeBySegment()). This is because FluentCrm\Framework\Database\Orm\Builder does not implement Traversable/IteratorAggregate, so foreach ($builder as $item) iterates over zero items instead of query results.

Steps to Reproduce

1. Create a campaign via REST API: POST /fluent-crm/v2/campaigns
2. Set content: PUT /fluent-crm/v2/campaigns/{id}
3. Set recipients: POST /fluent-crm/v2/campaigns/{id}/draft-recipients with tag filter — returns correct count
4. Process recipients: POST /fluent-crm/v2/campaigns/{id}/subscribe with same filter — returns "Sorry, No subscribers found based on your filters"

Root Cause

In Campaign::subscribeBySegment() (Campaign.php):

$model = $this->getSubscribersModel($settings); // Returns Orm\Builder
$totalCount = $model->count(); // Works: returns correct count
// ...
$result = $this->subscribe($model, [], true); // Fails silently

In Campaign::subscribe():

if ($isModel) {
    $subscribers = $subscriberIds; // This is an Orm\Builder, not a Collection
}

foreach ($subscribers as $subscriber) { // Zero iterations!
    // ...
}

Verification — Orm\Builder is not iterable:

$model = $campaign->getSubscribersModel($settings);
var_dump($model instanceof \Traversable); // false
var_dump(is_iterable($model));            // false
var_dump(class_implements(get_class($model))); // [] (no interfaces)

// foreach gives 0 results:
foreach ($model as $item) { /* never executes */ }

// But ->get() works:
$model->get()->count(); // Returns correct count

Suggested Fix

In Campaign::subscribe(), call ->get() when $isModel is true and the value is a Builder:

if ($isModel) {
    $subscribers = $subscriberIds;
    if ($subscribers instanceof \FluentCrm\Framework\Database\Orm\Builder) {
        $subscribers = $subscribers->get();
    }
}

Or alternatively, in subscribeBySegment():

// Before:
$result = $this->subscribe($model, [], true);

// After:
$result = $this->subscribe($model->get(), [], true);

Impact

• The POST /campaigns/{id}/subscribe REST endpoint is completely non-functional
• The admin UI is not affected because it uses the schedule endpoint which processes recipients via a background AJAX handler (fluentcrm-post-campaigns-emails-processing) instead of calling subscribe
• Any third-party integration or API automation that calls the subscribe endpoint will silently fail with 0 recipients

Environment

• FluentCRM (free) latest as of 2026-03-02
• WordPress 6.x
• PHP 8.x