Metadata API Reference: Event Triggers

Introduction

Event triggers are used to capture database changes and send them to a configured webhook.

Supported from

The metadata API is supported for versions v2.0.0 and above and replaces the older schema/metadata API.

pg_create_event_trigger

pg_create_event_trigger is used to create a new event trigger or replace an existing event trigger.

POST /v1/metadata HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin

{
    "type" : "pg_create_event_trigger",
    "args" : {
        "name": "sample_trigger",
        "table": {
           "name": "users",
           "schema": "public"
        },
        "source": "default",
        "webhook": "https://httpbin.org/post",
        "insert": {
            "columns": "*",
            "payload": ["username"]
        },
        "update": {
            "columns": ["username", "real_name"],
            "payload": "*"
        },
        "delete": {
            "columns": "*"
        },
        "headers":[
          {
              "name": "X-Hasura-From-Val",
              "value": "myvalue"
          },
          {
              "name": "X-Hasura-From-Env",
              "value_from_env": "EVENT_WEBHOOK_HEADER"
          }
        ],
        "replace": false
    }
}

Args syntax

Key	Required	Schema	Description
name	true	TriggerName	Name of the event trigger
table	true	QualifiedTable	Object with table name and schema
source	false	SourceName	Name of the source database of the table (default: default)
webhook	false	String	Full url of webhook (*)
webhook_from_env	false	String	Environment variable name of webhook (must exist at boot time) (*)
insert	false	OperationSpec	Specification for insert operation
update	false	OperationSpec	Specification for update operation
delete	false	OperationSpec	Specification for delete operation
headers	false	[ HeaderFromValue | HeaderFromEnv ]	List of headers to be sent with the webhook
retry_conf	false	RetryConf	Retry configuration if event delivery fails
replace	false	Boolean	If set to true, the event trigger is replaced with the new definition
enable_manual	false	Boolean	If set to true, the event trigger can be invoked manually
request_transform	false	RequestTransformation	Attaches a Request Transformation to the Event Trigger.
response_transform	false	ResponseTransformation	Attaches a Request Transformation to the Event Trigger.

(*) Either webhook or webhook_from_env are required.

pg_delete_event_trigger

pg_delete_event_trigger is used to delete an event trigger.

POST /v1/metadata HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin

{
    "type" : "pg_delete_event_trigger",
    "args" : {
        "name": "sample_trigger",
        "source": "default"
    }
}

Args syntax

Key	Required	Schema	Description
name	true	TriggerName	Name of the event trigger
source	false	SourceName	Name of the source database of the trigger (default: default)

pg_redeliver_event

redeliver_event is used to redeliver an existing event. For example, if an event is marked as error ( say it did not succeed after retries), you can redeliver it using this API. Note that this will reset the count of retries so far. If the event fails to deliver, it will be retried automatically according to its retry_conf.

POST /v1/metadata HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin

{
    "type" : "pg_redeliver_event",
    "args" : {
        "event_id": "ad4f698f-a14e-4a6d-a01b-38cd252dd8bf"
    }
}

Args syntax

Key	Required	Schema	Description
event_id	true	String	UUID of the event

pg_invoke_event_trigger

invoke_event_trigger is used to invoke an event trigger with custom payload.

POST /v1/metadata HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin

{
    "type" : "pg_invoke_event_trigger",
    "args" : {
        "name": "sample_trigger",
        "source": "default",
        "payload": {}
    }
}

Args syntax

Key	Required	Schema	Description
name	true	TriggerName	Name of the event trigger
payload	true	JSON	Some JSON payload to send to trigger
source	false	SourceName	Name of the source database of the trigger (default: default)