Projects using Clojure spec - next-jdbc

The next-jdbc project is a modern low-level Clojure wrapper for JDBC-based access to databases.

The project defines data specifications using predicates and

Defining specifications

Specifications are defined within a single file src/next/jdbc/specs.clj.

Specifications start with clojure.spec.alpha/def expressions, using predicate functions as specifications. There is also a custom predicate function called

Function definition specifications follow, using the clojure.spec.alpha/fdef function. The fdef functions define the specification for the arguments of each function. The fdef function name is the same as the function definition it is defining a specification for.

Instrumenting specifications

Instrumenting functions provides automatic checking that argument in a function call conforms to the specification.

Rather than write individual expressions to instrument each function, a var called fns-with-specs contains a collection of names for all the fdef function definition specifications.

(def ^:private fns-with-specs
  [`jdbc/get-datasource
   `jdbc/get-connection
   `jdbc/prepare
   `jdbc/plan
   `jdbc/execute!
   `jdbc/execute-one!
   `jdbc/transact
   `jdbc/with-transaction
   `connection/->pool
   `prepare/execute-batch!
   `prepare/set-parameters
   `prepare/statement
   `sql/insert!
   `sql/insert-multi!
   `sql/query
   `sql/find-by-keys
   `sql/get-by-id
   `sql/update!
   `sql/delete!])

Instrument all the functions by passing fns-with-specs as an argument to the clojure.spec.test.alpha/instrument function.

This call is wrapped in a simple handler function for convenience.

(defn instrument []
  (clojure.spec.test.alpha/instrument fns-with-specs))

To remove the checking of argument specifications, clojure.spec.test.alpha/unstrument is passed fns-with-specs, again wrapped in a convinced function.

(defn unstrument []
  (clojure.spec.test.alpha/unstrument fns-with-specs))