Can a tuple value be added when one of the parts of the tuple is an lookup-ref?

Thu, 20 Apr 2023 20:09:32 +0000

I'm wanting to use a lookup ref instead of an entity id (:db-id) when specifying the value for a tuple of attributes where one of the attributes is of type :db.type/ref. Is this possible? I've looked over the Datomic Cloud grammar on transactions and I don't see how to specify a tuple value at all (maybe I'm missing something). I've tried what I thought would be the obvious way to do it and this doesn't work. Here's what I have...

Truncated schema:

{:db/ident       :molecule/legacy-id
 :db/unique      :db.unique/identity
 :db/valueType   :db.type/long
 :db/cardinality :db.cardinality/one
 :db/doc         "The Molecule/Complex id from the ProcessDB Oracle database."}
{:db/ident       :molecule-part/number
 :db/valueType   :db.type/long
 :db/cardinality :db.cardinality/one
 :db/doc         "The number of molecules for this molecule. The entity with this attribute may be reused and is
 not unique for a particular complex so do not change this number. Instead, check for another existing entity
 or create one."}
{:db/ident       :molecule-part/molecule
 :db/valueType   :db.type/ref
 :db/cardinality :db.cardinality/one
 :db/doc         "The molecule this part refers to. The entity with this attribute may be reused and is
 not unique for a particular complex."}
{:db/ident       :molecule-part/number+molecule
 :db/unique      :db.unique/identity
 :db/valueType   :db.type/tuple
 :db/tupleAttrs  [:molecule-part/number :molecule-part/molecule]
 :db/cardinality :db.cardinality/one
 :db/doc         "The number and molecule that collectively form the unique identity of this entity."}

Then I try to add a molecule part using

(d/transact (db/get-connection) {:tx-data [{:molecule-part/molecule [:molecule/legacy-id 717] :molecule-part/number 1 :molecule-part/number+molecule [1 [:molecule/legacy-id 717]]}]})

And get the following error

:db.error/invalid-tuple-value Invalid tuple value

If I replace "[:molecule/legacy-id 717]" with the entity id (:db/id) for that molecule then it works. But I don't want to use the entity id... I want to use the lookup ref, because what I have is the :molecule/legacy-id. I don't want to have to do a query to resolve this before doing a transaction to add the :molecule-part.

Is using entid function to resolve lookup refs a supported behaviour?

Wed, 08 Jun 2022 13:30:29 +0000

I'm using datomic.api/entid to resolve a lookup ref to an entity ID, like
$ (entid db [:user/id "test@test.com"]) 17592186045432
This works fine, but a colleague pointed out this is not a documented behaviour.
>Usage: (entid db ident)
>Returns the entity id associated with a symbolic keyword, or the id
itself if passed.

Is this a gap in documentation, or is this behaviour accidental and not recommended to rely on?

Datomic Knowledgebase - Recent questions tagged lookup refs

Can a tuple value be added when one of the parts of the tuple is an lookup-ref?

Is using entid function to resolve lookup refs a supported behaviour?