Mismatch error in ThingsDB: type with relations must be created using a property on a stored thing

Question

I'm playing with relations between types in ThingsDB. When creating a new instance of a type, how am I supposed to create the relation?

This is my simplified collection set-up:

new_type('Person');
new_type('Workspace');

set_type('Person', {
    name: 'str',
    workspaces: '{Workspace}',
});
set_type('Workspace', {
    name: 'str',
    owner: 'Person?'
});
mod_type('Person', 'rel', 'workspaces', 'owner');

.alice = Person{
    name: 'Alice'
};

When creating a workspace with owner Alice, I get the following error:

w = Workspace{
    name: 'Foo',
    owner: .alice
};

// mismatch in type `Workspace` on property `owner`; relations must be created using a property on a stored thing (a thing with an Id)

Answer 1

Relations in ThingsDB work in both directions. Instead of assigning the owner, you should add the workspace to Alice. That is what the error message is referring to: "using a property on a stored thing". This is the thing which is assigned to the collection and therefore has an Id.

w = Workspace{name: 'Foo'};
.alice.workspaces.add(w);

// The workspace owner (w.owner) is now automatically set because of the relation