Hook Examples

Ready-to-use cloud function recipes for the most common hook patterns.

Auth Hooks

Invite-Only Registration

Only users with a valid invite code in their signup data can register. Hook: pre_register

def main():
    data = req.payload.get("data", {})
    invite_code = data.get("invite_code", "")

    if not invite_code:
        return {"block": True, "reason": "An invite code is required to sign up."}

    # Look up code in invites collection
    invite = db.find_one("invites",
        code=invite_code,
        used=False
    )

    if not invite:
        return {"block": True, "reason": "Invalid or expired invite code."}

    # Mark invite as used so it can't be reused
    db.update_document("invites", invite["id"], {"used": True})
    return {"block": False}

Block Disposable Emails

Reject signups from known throwaway email services. Hook: pre_register

BLOCKED_DOMAINS = [
    "mailinator.com", "tempmail.com", "guerrillamail.com",
    "throwam.com", "yopmail.com", "sharklasers.com",
]

def main():
    email = req.payload.get("email", "").lower()
    domain = email.split("@")[-1] if "@" in email else ""

    if domain in BLOCKED_DOMAINS:
        return {
            "block": True,
            "reason": "Disposable email addresses are not allowed. Please use a real email."
        }

    return {"block": False}

Create a profile, default settings, and a welcome notification when a user registers. Hook: post_register

def main():
    user = req.payload.get("user", {})
    user_id = user["id"]
    data = user.get("data", {})

    # Create profile
    db.create_document("profiles", {
        "user_id": user_id,
        "display_name": data.get("name", ""),
        "avatar_url": None,
        "bio": "",
    })

    # Create default settings
    db.create_document("user_settings", {
        "user_id": user_id,
        "email_notifications": True,
        "theme": "light",
        "language": "en",
    })

    # Create welcome notification
    db.create_document("notifications", {
        "user_id": user_id,
        "type": "welcome",
        "message": f"Welcome to the app{', ' + data['name'] if data.get('name') else ''}! 🎉",
        "read": False,
    })

    return {"ok": True}

Suspend / Ban System

Block login for users flagged as banned, with a reason shown to the user. Hook: pre_login

def main():
    user = req.payload.get("user", {})
    data = user.get("data", {})

    if data.get("is_banned"):
        reason = data.get("ban_reason") or "Your account has been suspended. Contact support."
        return {"block": True, "reason": reason}

    # Optional: also block deactivated accounts
    if data.get("status") == "deactivated":
        return {
            "block": True,
            "reason": "Your account has been deactivated. Reactivate it at myapp.com/account."
        }

    return {"block": False}

Record every login with timestamp and increment a counter. Hook: post_login

def main():
    user = req.payload.get("user", {})
    user_id = user.get("id")
    data = user.get("data", {})

    # Update login stats on the user record
    db.update_app_user(user_id, data={
        "last_login_at": datetime.utcnow().isoformat(),
        "login_count": (data.get("login_count") or 0) + 1,
    })

    # Also write to a login history collection for audit purposes
    db.create_document("login_history", {
        "user_id": user_id,
        "email": user.get("email"),
        "logged_in_at": datetime.utcnow().isoformat(),
    })

    return {"ok": True}

Post a Slack message whenever a new user registers. Hook: post_register

def main():
    user = req.payload.get("user", {})
    slack_url = config.get("SLACK_WEBHOOK_URL")

    if not slack_url:
        return {"ok": True}

    name = user.get("data", {}).get("name") or user.get("email")
    http.post(slack_url, json={
        "text": f"🎉 New signup: *{name}* (`{user['email']}`)"
    })

    return {"ok": True}

Store SLACK_WEBHOOK_URL in your project’s environment config (Dashboard → Settings → Environment).

Collection Hooks

Auto-Timestamp Every Document

Add updated_at to every document automatically on save. Hook: pre_save

def main():
    doc = req.payload.get("document", {})
    op = req.payload.get("operation")

    # You can't modify the document from a hook (it's already committed or about to be)
    # Instead use this to write to a separate audit collection
    db.create_document("document_history", {
        "collection": req.payload.get("collection"),
        "operation": op,
        "snapshot": doc,
        "timestamp": datetime.utcnow().isoformat(),
    })

    return {"ok": True}

Note: Hooks cannot modify the document being saved. To set timestamps automatically, use cloud functions as your write endpoint instead, or handle it on the client side.

Sync to a Search Index

After a document is saved, push it to an external search service (e.g. Algolia, Meilisearch, Typesense). Hook: post_save

def main():
    doc = req.payload.get("document", {})
    doc_id = req.payload.get("document_id")
    op = req.payload.get("operation")
    collection = req.payload.get("collection")

    if collection != "posts":
        return {"ok": True}

    # Only index published posts
    if doc.get("status") != "published":
        return {"ok": True}

    search_api_key = config.get("TYPESENSE_API_KEY")
    search_host = config.get("TYPESENSE_HOST")

    http.put(
        f"{search_host}/collections/posts/documents/{doc_id}",
        json={
            "id": doc_id,
            "title": doc.get("title"),
            "body": doc.get("body"),
            "author": doc.get("author"),
        },
        headers={"X-TYPESENSE-API-KEY": search_api_key}
    )

    return {"ok": True}

Remove from Search Index on Delete

Hook: post_delete

def main():
    doc_id = req.payload.get("document_id")
    collection = req.payload.get("collection")

    if collection != "posts":
        return {"ok": True}

    search_api_key = config.get("TYPESENSE_API_KEY")
    search_host = config.get("TYPESENSE_HOST")

    http.delete(
        f"{search_host}/collections/posts/documents/{doc_id}",
        headers={"X-TYPESENSE-API-KEY": search_api_key}
    )

    return {"ok": True}

Archive Deleted Documents

Save a copy before deletion so data is never permanently lost. Hook: pre_delete

def main():
    doc = req.payload.get("document", {})
    doc_id = req.payload.get("document_id")
    collection = req.payload.get("collection")

    db.create_document("archive", {
        "source_collection": collection,
        "source_id": doc_id,
        "data": doc,
        "archived_at": datetime.utcnow().isoformat(),
    })

    return {"ok": True}

Notify on Document Change (Email)

Send an email when an order document’s status changes. Hook: post_save

def main():
    doc = req.payload.get("document", {})
    old = req.payload.get("old_data", {})
    op = req.payload.get("operation")

    # Only care about updates where status changed
    if op != "update":
        return {"ok": True}

    new_status = doc.get("status")
    old_status = old.get("status")

    if new_status == old_status:
        return {"ok": True}

    customer_email = doc.get("customer_email")
    if not customer_email:
        return {"ok": True}

    email.send(
        to=customer_email,
        subject=f"Order #{doc.get('order_number')} is now {new_status}",
        body=f"""
Hi there,

Your order #{doc.get('order_number')} status has been updated to: {new_status}.

Track your order at myapp.com/orders/{doc.get('id')}.

Thanks!
        """.strip()
    )

    return {"ok": True}

Tips

Access Project Config in Hooks

Store API keys and secrets in your project’s environment config (Dashboard → Settings → Environment), then read them with config.get():

api_key = config.get("MY_SERVICE_API_KEY")

Don’t Block on External Calls

For pre_login and pre_register hooks, always wrap external HTTP calls in try/except so a slow or failing external service doesn’t block your users:

def main():
    try:
        result = http.post("https://external.service.com/check", json={...})
        if result.get("blocked"):
            return {"block": True, "reason": result.get("reason")}
    except:
        pass  # fail-open — never block users due to external service issues

    return {"block": False}

One Function, Multiple Events

You can attach the same cloud function to multiple hook events and branch on req.payload.get("event"):

def main():
    event = req.payload.get("event")

    if event == "post_register":
        # handle registration
        pass
    elif event == "post_login":
        # handle login
        pass

    return {"ok": True}

Getting Started

Core Concepts

Data & Querying

Cloud Functions

Hooks

Realtime & Multiplayer

Storage

Auth & Security

Guides

SDK Reference

API Reference

Hook Examples

Hook Examples

Auth Hooks

Invite-Only Registration

Block Disposable Emails

Suspend / Ban System

Collection Hooks

Auto-Timestamp Every Document

Sync to a Search Index

Remove from Search Index on Delete

Archive Deleted Documents

Notify on Document Change (Email)

Tips

Access Project Config in Hooks

Don’t Block on External Calls

One Function, Multiple Events

​Hook Examples

​Auth Hooks

​Invite-Only Registration

​Block Disposable Emails

​Onboarding: Create Default Records on Signup

​Suspend / Ban System

​Track Login Activity

​Notify Team on New Signup (Slack)

​Collection Hooks

​Auto-Timestamp Every Document

​Sync to a Search Index

​Remove from Search Index on Delete

​Archive Deleted Documents

​Notify on Document Change (Email)

​Tips

​Access Project Config in Hooks

​Don’t Block on External Calls

​One Function, Multiple Events

Hook Examples

Auth Hooks

Invite-Only Registration

Block Disposable Emails

Onboarding: Create Default Records on Signup

Suspend / Ban System

Track Login Activity

Notify Team on New Signup (Slack)

Collection Hooks

Auto-Timestamp Every Document

Sync to a Search Index

Remove from Search Index on Delete

Archive Deleted Documents

Notify on Document Change (Email)

Tips

Access Project Config in Hooks

Don’t Block on External Calls

One Function, Multiple Events