How to get all ref attribute values? - clojure

Question

I touch an entity and get many entity ids. I want all the attribute values instead of the ids while keeping the nested structure.
(d/touch (d/entity (get-db) (ffirst (find-all-families))))
=> {:family/parent #{{:db/id 17592186045423}
{:db/id 17592186045424}
{:db/id 17592186045426}
{:db/id 17592186045427}},
:family/child #{{:db/id 17592186045420}
{:db/id 17592186045421}},
:family/address {:db/id 17592186045428},
:family/email "someemail#gmail.com",
:db/id 17592186045429}
Thought about using something like simply touching all the entity ids but seems like complexity creeps up if I want all of them:
(map d/touch (:family/parent (d/touch (d/entity (get-db) (ffirst (find-all-families))))))
Not sure what the idiomatic approach is: finding a way to do it more through the querying side or through clojure.

Answer 1

The idiomatic way to do this in Datomic is to declare components in your schema. touch will touch all of the attributes of the entity, including any components recursively

Answer 2

You will probably wish to use the Datomic Pull API for this purpose. It can recursively return the attr/value pairs for all sub-entities that the user designates as "component". An example:
(def dark-side-of-the-moon [:release/gid #uuid "24824319-9bb8-3d1e-a2c5-b8b864dafd1b"])
(d/pull db [:release/media] dark-side-of-the-moon)
; result
{:release/media
[{:db/id 17592186121277,
:medium/format {:db/id 17592186045741},
:medium/position 1,
:medium/trackCount 10,
:medium/tracks
[{:db/id 17592186121278,
:track/duration 68346,
:track/name "Speak to Me",
:track/position 1,
:track/artists [{:db/id 17592186046909}]}
{:db/id 17592186121279,
:track/duration 168720,
:track/name "Breathe",
:track/position 2,
:track/artists [{:db/id 17592186046909}]}
{:db/id 17592186121280,
:track/duration 230600,
:track/name "On the Run",
:track/position 3,
:track/artists [{:db/id 17592186046909}]}
...]}]}
You may also use the Tupelo Datomic Pull API, which I think is nicer. As an example:
; If you wish to retain duplicate results on output, you must use td/query-pull and the Datomic
; Pull API to return a list of results (instead of a set).
(let [result-pull (td/query-pull :let [$ (live-db)] ; $ is the implicit db name
:find [ (pull ?eid [:location]) ] ; output :location for each ?eid found
:where [ [?eid :location] ] ) ; find any ?eid with a :location attr
result-sort (sort-by #(-> % first :location) result-pull)
]
(is (s/validate [ts/TupleMap] result-pull)) ; a list of tuples of maps
(is (= result-sort [ [ {:location "Caribbean"} ]
[ {:location "London" } ]
[ {:location "London" } ] ] )))