Is it possible to pass projection-spec for pull as query argument?

Users
1

The following minimal example fails with an error Query didn't match expected structure:

(def pull-pattern
  [:xt/id
   :name
   :created-at])

(xt/q (xt/db node)
 '{:find  [(pull ?e pattern)]
   :in    [?name pattern]
   :where [[?e :name ?name]]}
 "example name" pull-pattern)

This one works normally:

(xt/q (xt/db node)
 '{:find  [(pull ?e [:xt/id :name :created-at])]
   :in    [?name]
   :where [[?e :name ?name]]}
 "example name")

I’m very new to XTDB and running it with the following configuration:

documet-store: AWS S3
tx-log: JDBC on AWS RDS - Aurora
index-store: RocksDB
2

As per @refset …

Not currently, unfortunately, so you will have to construct the query dynamically:

(xt/q (xt/db node)
 {:find  [(list 'pull '?e pull-pattern)]
  :in    '[?name]
  :where '[[?e :name ?name]]}
 "example name")

you could also use the pull API as a separate step, or even create a custom function that does the work inside a subquery (e.g. something a little simpler than this lazy-authz-subquery-with-limit · GitHub …but hopefully it gives some idea)

3

A solution could be as following, however as @refset mentioned on Slack, this could have different performance characteristics based on the configuration etc.

(->> (xt/q db '{:find [?e]
                :in   [?name]
                :where [[?e :name ?name]]}
           "example name")
     (map first)
     (xt/pull-many db pull-pattern))