NodeJS Mutation Example on Zeit

If you haven't already, follow the first part of instructions here.

This example trigger updates (executes a mutation) when an event occurs on another table, written in NodeJS.

Create tables

Table name: note

Columns:

id     Integer auto-increment
note   Text

Primary key: id

Table name: note_revision

Columns:

id         Integer auto-increment
note       Text
note_id    Integer
update_at  Timestamp, default: now()

Primary key: id

Deploy the function

Execute now in this directory with an env var required for the code to execute a mutation:

now -e HGE_ENDPOINT=https://my-app.herokuapp.com/v1/graphql

HGE_ENDPOINT is the Hasura GraphQL Engine endpoint.

Once the deployment is done, you'll get an endpoint like https://zeit-mutation-hhasdewasd.now.sh. Not this down as NOW_URL.

Note: Now.sh deployments are immutable, i.e. each time you deploy the code, a new URL will be provisioned. You can alias the deployment to keep a constant URL.

Create the trigger

Goto Hasura console, Events tab and create a new trigger:

Trigger name: note_revision_trigger

Schema/Table: public/note

Operations: Update

Webhook URL: NOW_URL

Replace NOW_URL with the URL noted earlier.

Test the trigger

Goto Data tab on Hasura console, browse to note table and to the Browse rows tab. Edit an existing note and check if the note_revision entry has been created. Also, checkout the trigger request and response.

Trigger payload (request):

{
    "event": {
        "op": "UPDATE",
        "data": {
            "old": {
                "note": "note1",
                "id": 1
            },
            "new": {
                "note": "note1 updated",
                "id": 1
            }
        }
    },
    "created_at": "2018-10-02T06:38:22.67311Z",
    "id": "f57a1c79-72ba-4c19-8791-37d1b9616bcf",
    "trigger": {
        "name": "note_revision_trigger",
        "id": "5d85cbd1-c134-45ce-810c-7ecd3b4fc1ee"
    },
    "table": {
        "schema": "public",
        "name": "note"
    }
}

Webhook response:

{
    "result": {
        "data": {
            "insert_note_revision": {
                "returning": [
                    {
                        "__typename": "note_revision",
                        "id": 1
                    }
                ],
                "affected_rows": 1,
                "__typename": "note_revision_mutation_response"
            }
        }
    }
}