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2b5550c346
Lead with a complete plugin quick start and add task-oriented usage, troubleshooting, customization, and contribution guides. Preserve the broader plugin framing, correct conflicting contract guidance, support Agents folder reviews, and align repository validation. Convert existing sample references to clickable links without changing knowledge rules. Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com> Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
26 lines
2.5 KiB
Markdown
26 lines
2.5 KiB
Markdown
---
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bc-version: [all]
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domain: events
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keywords: [event-subscriber, static-subscriber, manual-subscriber, bindsubscription, unbindsubscription, eventsubscriberinstance, scoped-binding]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# Choose static vs manual subscribers deliberately and bind manual ones with BindSubscription
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## Description
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An `[EventSubscriber]` codeunit is static by default (`EventSubscriberInstance = StaticAutomatic`): it is always bound, so it fires for every raise of the event in every session. That is correct for always-on behaviour such as auditing, but wrong for behaviour that must be scoped — test isolation, a one-off migration, or a conditional override — because a static subscriber cannot be switched off. For scoped behaviour, set `EventSubscriberInstance = Manual` and activate the codeunit only while needed with `BindSubscription`, releasing it with `UnbindSubscription`. LLMs are largely unaware the manual model exists and default everything to static, producing always-on side effects that leak across unrelated operations and tests.
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## Best Practice
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Use a static subscriber for behaviour that genuinely applies all the time. For anything scoped, mark the codeunit `EventSubscriberInstance = Manual`, call `BindSubscription(SubscriberInstance)` at the start of the scope and `UnbindSubscription(SubscriberInstance)` at the end. A manual subscriber held only in a local variable unbinds automatically when that variable leaves scope, which suits test setup/teardown; a binding you intend to outlive a single call must be unbound explicitly. Keep subscriber methods `local` per CodeCop AA0207.
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See sample: [`choose-static-vs-manual-subscribers-deliberately.good.al`](choose-static-vs-manual-subscribers-deliberately.good.al).
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## Anti Pattern
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Two shapes. First, a static subscriber used for behaviour that should be scoped — an always-on side effect (sending mail, writing extra records) that now fires for every event in every session and test with no way to disable it. Second, a manual subscriber that is bound with `BindSubscription` and never unbound: when the instance is held beyond the intended scope (for example on a `SingleInstance` codeunit), the binding leaks for the whole session and later unrelated operations keep hitting it. Detection: scoped side effects on a static subscriber, or a `BindSubscription` call with no matching `UnbindSubscription` and no scope that releases the instance.
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See sample: [`choose-static-vs-manual-subscribers-deliberately.bad.al`](choose-static-vs-manual-subscribers-deliberately.bad.al).
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