Clojurians Log v2

> and then using that in subsequent `:db/retract` statements. yes exactly. I wonder if in the prior example giving a :db/ident say “id” instead of the tempid -1, then a retraction statement like [:db/retract "id" :person/address "10999"] would have worked. I tend to think about db/idents as https://docs.datomic.com/on-prem/schema/identity.html#lookup-refs but maybe I should not. Do Asami tx data in the vector form only support actual db/ids? (in other words node-1 mentioned in the wiki https://github.com/threatgrid/asami/wiki/Transactions#tx-data has to be a db/id)

When I found the bug I did notice that it does not support this. I thought that maybe it should, but then realized that this sort of statement means that you are explicitly trying to remove statements during the same transaction that you’re trying to add them. This doesn’t make sense (in Datomic it causes an exception). It’s also difficult, because transactions are performed by performing deletions, followed by assertions. To make it work, these deletions would have to occur after the assertions that autogenerate that ID. Otherwise they’d delete a non-existing statement (a no-op) before inserting it, meaning that the statement would still be created.

I could make it work, but I see no reason why it should. Unless there’s a use-case I’m not seeing?

I think @andrea712 is talking about "id" as a :db/ident , not a temp id

is it possible to perform a retraction using an :db/ident?

asami does not support datomic style lookup refs, e.g. [:db/ident "id"] correct?

no, sorry for the confusion, it’s me not understanding well enough the :db/ident construct: I thought, since they can be used to lookup an entity which was asserted at any time via (asami.core/entity db my-ident) I thought that values of :db/ident could be used in vector statements for retractions in tx-data in 2nd position: eg [:db/retract my-ident attr val]

Asami doesn’t have that lookup style… no. I made a ticket for it (and it won’t be hard), but it hasn’t been a priority.

ok, so if you want to retract an attribute using a :db/ident you need to do a query for its :db/id first, correct?

okay, we’re currently resolving :db/idents -> :db/id in retraction statements before transactions and it works well enough for the moment, I think

yes @mkvlr doing that currently

idents are used for identifying entities, and we (as in… my team) only really wants to delete things from entities when updating a property (meaning, delete the existing statement, and insert a new one), then we’ve used the entity update annotation for that

Internally, all the entity code does those lookups for you. Which is to say that there’s no big deal moving it to other places as well.

understood, supporting [:db/retract [:db/ident my-ident] attr val] would be useful for us, but of course also easy for us to do it before we submit the tx

So if I have the entity:

{:db/ident "Mary"
 :name "Mary Smith"
 :age 22}

{:db/ident "Mary"
 :age' 23}

Sorry… I have to leave for an hour

yes, so given that entity with a :db/id :

{:db/id 123
 :db/ident "Mary"
 :name "Mary Smith"
 :age 22}

also happy to look at that (probably tomorrow) if you’d accept a PR for this

If so, then it would go in src/asami/entities.cljc:133 and would probably do something like what line 60 does in that file

(let [node-ref (if id
                             (and (seq (gr/resolve-triple graph id '?a '?v)) id)
                             (ffirst (gr/resolve-triple graph '?r :db/ident ident)))

the resolve-triple function returns a seq of bindings values. A bindings values is a vector containing position dependent bindings for the requested variables. So the first one will return a seq of vectors that have a count of 2 (representing values for the ?a and ?v), and the second will return a seq containing (hopefully) 1 vector, and that vector will have a count of 1.

The (if id … part means that if a :db/id is provided, then that is considered canonical, and ignore the :db/ident

These notes are in case you want to go ahead and do it. Otherwise, they’re a prompt for me to get it done 😉

(oh… when I said line 133, that was for the deletions. Assertions will need to be treated the same way)

thanks for those pointers, I’ll open a PR shortly

https://github.com/threatgrid/asami/pull/118

Thank you @mkvlr. I’ve responded to this

I also updated Zuko (which does the deconstruction of entities into triples) to include the lookup refs

It’s in main, and will come out in the next alpha

thank you again

thank you!