Execute function "on before create" a document in a collection

[dj-fiorex]

Hello everyone,

I recently transitioned from Firebase to AppWrite and I'm trying to find a way to trigger a function before a document is created in a collection. Specifically, I want to add certain properties to a new document before it's actually created in the collection. Is there a mechanism in AppWrite for achieving this?

I have already reviewed the documentation and found the databases.*.collections.*.create event, but it triggers after the document has been created. I need to add required, calculated properties to ensure successful write operations.

Thank you for your assistance!

[wellkilo]

Appwrite database events are post-write events; they are notifications, not transactional before-create hooks. A Function triggered by databases..collections..documents.*.create therefore cannot add required fields before the original create is validated/committed.

Use a server-side command boundary instead:

1. The client calls an Appwrite Function (or your backend) with the user-supplied fields.
2. The Function authenticates/authorizes the caller and calculates the required properties.
3. The Function uses the Server SDK to create the document once with the complete payload.
4. Restrict direct client create permission on that collection/table so clients cannot bypass the Function.

Pseudo-code:

export default async ({ req, res, error }) => {
  const input = JSON.parse(req.body || '{}')

  // Validate req.headers / JWT and input here.
  const document = await databases.createDocument(
    DATABASE_ID,
    COLLECTION_ID,
    ID.unique(),
    {
      ...input,
      calculatedField: calculate(input),
      createdBy: req.headers['x-appwrite-user-id'],
    },
  )

  return res.json(document)
}

Do not create first and then patch from an event if the calculated fields are required for validity: clients can observe the intermediate state, the event can fail/retry, and the two writes are not one transaction.

If the field is only enrichment and eventual consistency is acceptable, an after-create event plus idempotent update is fine. For required/calculated input, the Function/backend-before-write pattern is the reliable design. If this resolves the architecture question, please mark it as accepted.