Trigger on Insert OR Update to configure a timestamp

[sdukehart-omnesoft]

I feel like I'm a bit dense here.

I haven't been able to get something like https://www.npgsql.org/efcore/modeling/generated-properties.html#timestamp-generation working:

CREATE FUNCTION "Blogs_Update_Timestamp_Function"() RETURNS TRIGGER LANGUAGE PLPGSQL AS $$
BEGIN
    NEW.timestamp := CURRENT_TIMESTAMP;
    RETURN NEW;
END;
$$;

CREATE TRIGGER "UpdateTimestamp"
    BEFORE INSERT OR UPDATE
    ON "Blogs"
    FOR EACH ROW
    EXECUTE FUNCTION "Blogs_Update_Timestamp_Function"();

I end up having to do something like:

        entity.BeforeInsert(trigger =>
            trigger.Action(action => action.ExecuteRawSql("NEW.timestamp = CURRENT_TIMESTAMP"))
        );
        entity.BeforeUpdate(trigger =>
            trigger.Action(action => action.ExecuteRawSql("NEW.timestamp = CURRENT_TIMESTAMP"))
        );

Ideally, I'd do something like:

        // Note BeforeInsertOrUpdate, which doesn't currently exist
        entity.BeforeInsertOrUpdate(trigger =>
            trigger.Action(action =>
                // Some NON "ExecuteRawSql" action here against my entity type
            )
        );

But I can't figure out:

1. How to do this without ExecuteRawSql
2. How to do something like a combined BeforeInsertOrUpdate (less of a concern as we can have a default value on the column)

Thanks for any insights.