Datomic - working with OR clause - clojure

Question

I'm currently working on migrating my clojure app(with korma) to Datomic framework and been in a loop while I was translating the queries. I realise the queries are not completely flexible(compared to korma), for example i would like to evaluate conditional clauses around different variables.
Considering a korma query,
(select users
(where (or (and {:first_name [= "user"]}
{:last_name [= "sample"]})
{:email [= "user.sample#email.com"]})))
this can be converted to Datomic, with something like this?
[:find ?e
:where (or (and [?u :user/first-name "user"]
[?u :user/last-name "sample"])
[?u :user/email "user.sample#email.com"])
but this is not the recommended way of querying(according to Datomic docs), as all clauses used in an or clause must use the same set of variables. How do I set an OR clause around different sets of variables?

Answer 1

Your query should work. All of your clauses do use the same variable: ?u
(d/q '[:find ?u
:where (or (and [?u :user/first-name "user"]
[?u :user/last-name "sample"])
[?u :user/email "user.sample#email.com"])]
[[1 :user/first-name "user"]
[1 :user/last-name "sample"]
[2 :user/email "user.sample#email.com"]
[3 :user/first-name "user"]
[3 :user/last-name "not sample"]])
=> #{[1] [2]}
If you need them to use different variables, you can use or-join to explicitly list them:
(d/q '[:find ?u
:in $ ?first-name ?last-name ?email
:where (or-join [?u ?first-name ?last-name ?email]
(and [?u :user/first-name ?first-name]
[?u :user/last-name ?last-name])
[?u :user/email ?email])]
[[1 :user/first-name "user"]
[1 :user/last-name "sample"]
[2 :user/email "user.sample#email.com"]
[3 :user/first-name "user"]
[3 :user/last-name "not sample"]]
"user"
"sample"
"user.sample#email.com")
=> #{[1] [2]}

Answer 2

This is very similar to this question:
SQL LIKE operator in datomic
You need to check out query rules.
http://docs.datomic.com/query.html
Your query would look something like this (untested!)
(let [rules '[[(find-user ?user ?fname ?lname ?email)
[?user :user/first-name ?fname]
[?user :user/last-name ?lname]]
[(find-user ?user ?fname ?lname ?email)
[?user :user/email ?email]]]]
(:find ?user
:in $ % ?fname ?lname ?email
:where
(find-user ?user ?fname ?lname ?email)
conn rules "user" "sample" "user.sample#email.com"))