Create event to relate records

[yagodorea]

Hey, I'm pretty new to SurrealDB and was playing with it. Is it possible to create an event that triggers a RELATE statement?

I'm struggling with it and the error messages are not very helpful.

DEFINE EVENT eventname ON tablenameb WHEN $event = 'CREATE' THEN (
  RELATE tablenamea:$value.from->parent->tablenamea:$value.to SET time = time::now()
);

This yields

Parse error on line 1 at character 0 when parsing 'DEFINE EVENT eventname ON tablenameb WHEN $event = 'CREATE' THEN (RELATE tablenamea:$value.from->par'

Adding an event to trigger a CREATE event works fine, but if I try to use a RELATE event it doesn't.

[AOx0]

I'm fairly new to SurrealQL but resolved to create it like this...

DEFINE EVENT relate_autor_collection ON collection WHEN $event = "CREATE" THEN {
    LET $autor = $auth.id;
    LET $collection = $value.id;
    RELATE $autor->owns->$collection;
};

Basically create symbols for the origin and target records because the $value.field seems to be invalid syntax in the context of a relate statement.

There is another example here @ #1820. For more details view the full comment.

DEFINE EVENT register_order ON TABLE user
WHEN ( $before.place_order != $after.place_order AND $after.place_order != NULL ) THEN {
    LET $from = place_order.from;
    LET $to = place_order.to;

    // Enforce that the user only creates orders for they businesses
    IF ($from.owner.id = $auth.id) THEN
        RELATE $from->order->$to
    END;

    // Reset the endpoint to null again
    UPDATE type::thing(id) SET place_order = NULL;
};

Edit: If anyone has a better way to do it I'll be glad to hear from it.

[nickchomey]

Here's a generic event that I've been using for this, but I do it in Golang when I create a table. It works by passing a sort of schema into the template placeholders

tmpl := template.Must(template.New("event").Parse(`
DEFINE EVENT IF NOT EXISTS {{.Name}}_relation ON TABLE {{.Trigger.Table}} 
WHEN $event = 'CREATE' 
AND $after.{{.Trigger.InField}} != NONE 
THEN {
    LET $in = IF type::is::record($after.{{.Trigger.InField}}) {
            $after.{{.Trigger.InField}} 
        } ELSE {
            type::thing('{{.InTable}}', $after.{{.Trigger.InField}})
        };
    LET $out = IF type::is::record($after.{{.Trigger.OutField}}) {
            $after.{{.Trigger.OutField}}
        } ELSE {
            type::thing('{{.OutTable}}', $after.{{.Trigger.OutField}})
        };
    
    RELATE $in->{{.Name}}->$out;
};`))