Skip to content

Latest commit

 

History

History
80 lines (74 loc) · 3.09 KB

README.md

File metadata and controls

80 lines (74 loc) · 3.09 KB
Raw

Specalog

Generate composable Datalog (Datomic) queries from your clojure.spec definitions.

Why?

  • Build on your shareable spec, not your Datomic API library
  • Pull from Datomic using custom views defined in your spec. No code updates required.
  • Validate data before it's transacted

How?

You probably have a spec that defines the shape of an entity in Datomic. For example, a Person entity might look like this:

(s/def :person/uuid uuid?)
(s/def :person/first-name string?)
(s/def :person/last-name string?)
(s/def :person/email string?)
(s/def :person/password string?)
(s/def :acme/person (s/keys :req [:person/uuid
                                  :person/email
                                  :person/password]
                            :opt [:person/first-name
                                  :person/last-name]))

specalog.query/pull-thing builds a query that finds all entities with values in the spec's :req key, while returnng those values and an additional ones found in the :opt keys.

Example Pull

Using Specalog, generate a Datalog query that pulls entities which fit the shape of the :acme/person spec

(q/pull-thing :acme/person)

And the result is a query with the following properties:

  1. Entities returned must have a value for all attributes in the spec's :req key
  2. Return all values from both the :req: and :opt keys.
; Result
{:find  [(pull ?acme-person [:person/uuid
                             :person/email
                             :person/password
                             :person/first-name
                             :person/last-name])]
 :in    [$]
 :where [[?acme-person :person/uuid]
         [?acme-person :person/email]
         [?acme-person :person/password]]}

Example Constraints

Specalog supports simple constraints by passing an optional constraint map to q/pull-thing. For example, find all people-like entities with a specific email address.

(q/pull-thing :acme/person {:person/email "[email protected]"})
{:find  [(pull ?acme-person [:person/uuid :person/email
                             :person/password
                             :person/first-name
                             :person/last-name])]
 :in    [$]
 :where [[?acme-person :person/email "[email protected]"]
         [?acme-person :person/uuid]
         [?acme-person :person/email]
         [?acme-person :person/password]]}

Validate Transactions

Use Specalog to validate input to a transaction

(q/put-thing :acme/person {:person/first-name "Jean-Luc"
                           :person/last-name  "Picard"
                           :person/email      "[email protected]"
                           :person/password   "makeitso"
                           :person/uuid       #uuid"c3a48253-0c34-4613-aca8-79749c6238bd"})
; Result
{:tx-data [#:person{:first-name "Jean-Luc",
                    :last-name "Picard",
                    :email "[email protected]",
                    :password "makeitso",
                    :uuid #uuid"c3a48253-0c34-4613-aca8-79749c6238bd"}]}