Clojure/Script tools for clojure.spec.
Status: Alpha (as spec is still alpha too).
Blogs:
Requires Java 1.8, tested with Clojure 1.9.0
and ClojureScript 1.10.439
+.
To enable spec metadata and features like Spec driven transformations, Spec-tools introduces extendable Spec Records, Spec
s. They wrap specs and act like specs or 1-arity functions. Specs are created with spec-tools.core/spec
macro or with the underlying spec-tools.core/create-spec
function.
The following Spec keys having a special meaning:
Key | Description |
---|---|
:spec | The wrapped spec (predicate). |
:form | The wrapped spec form. |
:type | Type hint of the Spec, mostly auto-resolved. Used in runtime conformation. |
:name | Name of the spec. Maps to title in JSON Schema. |
:description | Description of the spec. Maps to description in JSON Schema. |
:gen | Generator function for the Spec (set via s/with-gen ) |
::parse/keys | Set of all map keys that the spec defines. Extracted from s/keys Specs. |
::parse/keys-req | Set of required map keys that the spec defines. Extracted from s/keys Specs. |
::parse/keys-opt | Set of optional map keys that the spec defines. Extracted from s/keys Specs. |
:reason | Value is added to s/explain-data problems under key :reason |
:decode/... | 2-arity function to transform a value from an external format. |
:encode/... | 2-arity function to transform a value into external format. |
:json-schema/... | Extra data that is merged with unqualifed keys into json-schema |
:swagger/... | Extra data that is merged with unqualifed keys into swagger-schema |
There are also some extra read-only keys from spec parsing, these all are namespaced with ::parse
(spec-tools.parse
).
The following are all equivalent:
(require '[spec-tools.core :as st])
;; using type inference
(st/spec integer?)
;; with explicit type
(st/spec integer? {:type :long})
;; map form
(st/spec {:spec integer?})
(st/spec {:spec integer?, :type :long})
;; function
(st/create-spec
{:spec integer?
:form `integer?
:type :long})
;; function, with type and form inference
(st/create-spec
{:spec integer?})
;; ... resulting in:
; #Spec{:type :long,
; :form clojure.core/integer?}
(require '[clojure.spec.alpha :as s])
(def my-integer? (st/spec integer?))
my-integer?
; #Spec{:type :long
; :form clojure.core/integer?}
(my-integer? 1)
; true
(s/valid? my-integer? 1)
; true
(assoc my-integer? :description "It's a int")
; #Spec{:type :long
; :form clojure.core/integer?
; :description "It's a int"}
(eval (s/form (st/spec integer? {:description "It's a int"})))
; #Spec{:type :long
; :form clojure.core/integer?
; :description "It's a int"}
For most core predicates, :type
can be resolved automatically using the spec-tools.parse/parse-form
multimethod.
For most core predicates, :form
can be resolved automatically using the spec-tools.form/resolve-form
multimethod.
Most clojure.core
predicates have a predefined Spec Record instance in spec-tools.spec
.
(require '[spec-tools.spec :as spec])
spec/boolean?
; #Spec{:type :boolean
; :form clojure.core/boolean?}
(spec/boolean? true)
; true
(s/valid? spec/boolean? false)
; true
(assoc spec/boolean? :description "it's an bool")
; #Spec{:type :boolean
; :form clojure.core/boolean?
; :description "It's a bool"}
Can be added to a Spec via the key :reason
(s/explain (st/spec pos-int? {:reason "positive"}) -1)
; val: -1 fails predicate: pos-int?, positive
(s/explain-data (st/spec pos-int? {:reason "positive"}) -1)
; #:clojure.spec.alpha{:problems [{:path [], :pred pos-int?, :val -1, :via [], :in [], :reason "positive"}]}
Like Plumatic Schema, Spec-tools differentiates specs (what) and transformers (how). This enables spec values to be transformed between different formats like JSON and EDN. Core concept is the Transformer
protocol:
(defprotocol Transformer
(-name [this])
(-encoder [this spec value])
(-decoder [this spec value]))
Spec-tools ships with following transformer implementations:
Name | Description |
---|---|
string-transformer | String-formats like properties files, query- & path-parameters. |
json-transformer | JSON format, like string, but numbers and booleans are supported |
strip-extra-keys-transformer | Decoding strips out extra keys of s/keys specs. |
fail-on-extra-keys-transformer | Decoding fails if s/keys specs have extra keys. |
nil | No transformations, EDN & Transit. |
For simple transformations, there is coerce
. It takes a spec, value and a transformer and uses a Spec Walker to walk over specs. It transforms all values it can, leaving non-coercable parts untouched. Behind the scenes, specs are walked using their s/form
& spec-tools form parser. It can't walk over all specs, and is thus not complete - waiting for CLJ-2251 to make it work with all specs. Inspired by spec-coerce
(st/coerce int? "1" st/string-transformer)
; 1
(st/coerce int? "1" st/json-transformer)
; "1"
(s/def ::c1 int?)
(s/def ::c2 keyword?)
(st/coerce
(s/map-of
keyword?
(s/or :keys (s/keys :req-un [::c1])
:ks (s/coll-of (s/and int?) :into #{})))
{"keys" {:c1 "1" ::c2 "kikka"}
"keys2" {:c1 true}
"ints" [1 "1" "invalid" "3"]}
st/string-transformer)
;{:keys {:c1 1, ::c2 :kikka}
; :keys2 {:c1 true}
; :ints #{1 "invalid" 3}}
Functions explain
, explain-data
, conform
and conform!
take the transformer an optional third argument and pass it into Specs via dynamic binding. Before CLJ-2116 or CLJ-2251 are fixed, specs need to be wrapped into Spec Records to make this work.
There are also encode
& decode
functions that combine the two approaces and concidered the best way to transform the values. decode
first tries to use coerce
and if that doesn't make the value valid against the given spec, fallbacks to conform
& unform
which can be used for all specs.
:encode/*
and :decode/*
keys from Specs to declare how the values should be transformed in & out from different formatsspec value => value
to do the actual transformation(require '[clojure.string :as str])
(s/def ::spec
(st/spec
{:spec #(and (simple-keyword? %) (-> % name str/lower-case keyword (= %)))
:description "a lowercase keyword, encoded in uppercase in string-mode"
:decode/string #(-> %2 name str/lower-case keyword)
:encode/string #(-> %2 name str/upper-case)}))
(st/decode ::spec :kikka)
; :kikka
(as-> "KiKka" $
(st/decode ::spec $))
; :clojure.spec.alpha/invalid
(as-> "KiKka" $
(st/decode ::spec $ st/string-transformer))
; :kikka
(as-> "KiKka" $
(st/decode ::spec $ st/string-transformer)
(st/encode ::spec $ st/string-transformer))
; "KIKKA"
no, as there can be multiple valid representations for a encoded value. But it can be quaranteed that a decoded values X is always encoded into Y, which can be decoded back into X: y -> X -> Y -> X
(as-> "KikKa" $
(doto $ prn)
(st/encode ::spec $ st/string-transformer)
(doto $ prn)
(st/decode ::spec $ st/string-transformer)
(doto $ prn)
(st/encode ::spec $ st/string-transformer)
(prn $))
; "KikKa"
; "KIKKA"
; :kikka
; "KIKKA"
:type
information from Specs
encode
& decode
etc are transformed into Spec Records automatically using IntoSpec
protocol.:long
, :double
, :boolean
, :string
, :keyword
, :symbol
, :uuid
, :uri
, :bigdec
, :date
, :ratio
, :map
, :set
and :vector
.(as-> "2014-02-18T18:25:37Z" $
(st/decode inst? $))
; :clojure.spec.alpha/invalid
;; decode using string-transformer
(as-> "2014-02-18T18:25:37Z" $
(st/decode inst? $ st/string-transformer))
; #inst"2014-02-18T18:25:37.000-00:00"
;; encode using string-transformer
(as-> "2014-02-18T18:25:37Z" $
(st/decode inst? $ st/string-transformer)
(st/encode inst? $ st/string-transformer))
; "2014-02-18T18:25:37.000+0000"
When creating custom specs, :type
gives you encoders & decoders (and docs!) for free, like with Data.Unjson.
(s/def ::kw
(st/spec
{:spec #(keyword %) ;; anonymous function
:type :keyword})) ;; encode & decode like a keyword
(st/decode ::kw "kikka" st/string-transformer)
;; :kikka
(st/decode ::kw "kikka" st/json-transformer)
;; :kikka
Because of current design of clojure.spec, we need to wrap all non top-level specs into Spec Records manually to enable transformations.
(s/def ::name string?)
(s/def ::birthdate spec/inst?)
(s/def ::languages
(s/coll-of
(s/and spec/keyword? #{:clj :cljs})
:into #{}))
(s/def ::user
(s/keys
:req-un [::name ::languages ::age]
:opt-un [::birthdate]))
(def data
{:name "Ilona"
:age "48"
:languages ["clj" "cljs"]
:birthdate "1968-01-02T15:04:05Z"})
;; no transformer
(st/decode ::user data)
; ::s/invalid
;; json-transformer doesn't transform numbers
(st/decode ::user data st/json-transformer)
; ::s/invalid
;; string-transformer for the rescue
(st/decode ::user data st/string-transformer)
; {:name "Ilona"
; :age 48
; :languages #{:clj :cljs}
; :birthdate #inst"1968-01-02T15:04:05.000-00:00"}
To strip out extra keys from a keyset:
(s/def ::name string?)
(s/def ::street string?)
(s/def ::address (st/spec (s/keys :req-un [::street])))
(s/def ::user (st/spec (s/keys :req-un [::name ::address])))
(def inkeri
{:name "Inkeri"
:age 102
:address {:street "Satamakatu"
:city "Tampere"}})
(st/decode ::user inkeri st/strip-extra-keys-transformer)
; {:name "Inkeri"
; :address {:street "Satamakatu"}}
There are also a shortcut for this, select-spec
:
(st/select-spec ::user inkeri)
; {:name "Inkeri"
; :address {:street "Satamakatu"}}
Transformers should have a simple keyword name and optionally type-based decoders, encoders, default decoder and -encoder set. Currently there is no utility to verify that y -> X -> Y -> X
holds for custom transformers.
(require '[clojure.string :as str])
(require '[spec-tools.transform :as stt])
(defn transform [_ value]
(-> value
str/upper-case
str/reverse
keyword))
;; string-decoding + special keywords
;; encoding writes strings by default
(def my-string-transformer
(type-transformer
{:name :custom
:decoders (merge
stt/string-type-decoders
{:keyword transform})
:default-encoder stt/any->string}))
(decode keyword? "kikka")
; :clojure.spec.alpha/invalid
(decode keyword? "kikka" my-string-transformer)
; :AKKIK
; spec-driven transforming
(decode
(spec
{:spec #(keyword? %)
:decode/custom transform})
"kikka"
my-string-transformer)
; :AKKIK
;; defaut encoding to strings
(encode int? 1 my-string-transformer)
; "1"
Type-based transformer encoding & decoding mappings are defined as data, so they are easy to compose:
(def strict-json-transformer
(type-transformer
{:name :custom
:decoders (merge
stt/json-type-decoders
stt/strip-extra-keys-type-decoders)
:encoders stt/json-type-encoders}))
(require '[spec-tools.data-spec :as ds])
Data Specs offers an alternative, Schema-like data-driven syntax to define simple nested collection specs. Rules:
{}
, Vectors []
and Sets #{}
ds/opt
or ds/req
for making them optional or required.ds/maybe
makes it s/nilable
NOTE: to avoid macros, current implementation uses the undocumented functional core of clojure.spec.alpha
: every-impl
, tuple-impl
, map-spec-impl
, nilable-impl
and or-spec-impl
.
NOTE: To use enums with data-specs, you need to wrap them: (s/spec #{:S :M :L})
(s/def ::age pos-int?)
;; a data-spec
(def person
{::id integer?
::age ::age
:boss boolean?
(ds/req :name) string?
(ds/opt :description) string?
:languages #{keyword?}
:aliases [(ds/or {:maps {:alias string?}
:strings string?})]
:orders [{:id int?
:description string?}]
:address (ds/maybe
{:street string?
:zip string?})})
;; it's just data.
(def new-person
(dissoc person ::id))
ds/spec
on it, providing either a options map or a qualified keyword describing the root spec name - used to generate unique names for sub-specs that will be registered. Valid options:Key | Description |
---|---|
:spec | The wrapped data-spec. |
:name | Qualified root spec name - used to generate unique names for sub-specs. |
:keys-spec | Function to wrap not-wrapped keys, e.g. ds/un to make keys optional by default. |
:keys-default | Function to generate the keys-specs, default ds/keys-specs . |
;; options-syntax
(def person-spec
(ds/spec
{:name ::person
:spec person}))
;; legacy syntax
(def person-spec
(ds/spec ::person person))
(def new-person-spec
(ds/spec ::person new-person))
(keys (st/registry #"user.*"))
; (:user/id
; :user/age
; :user$person/boss
; :user$person/name
; :user$person/description
; :user$person/languages
; :user$person$aliases$maps/alias
; :user$person/orders
; :user$person$orders/description
; :user$person$orders/id
; :user$person/address
; :user$person$address/street
; :user$person$address/zip)
(s/valid?
new-person-spec
{::age 63
:boss true
:name "Liisa"
:languages #{:clj :cljs}
:aliases [{:alias "Lissu"} "Liisu"]
:orders [{:id 1, :description "cola"}
{:id 2, :description "kebab"}]
:description "Liisa is a valid boss"
:address {:street "Amurinkatu 2"
:zip "33210"}})
; true
(st/encode
new-person-spec
{::age "63"
:boss "true"
:name "Liisa"
:languages ["clj" "cljs"]
:aliases [{:alias "Lissu"} "Liisu"]
:orders [{:id "1", :description "cola"}
{:id "2", :description "kebab"}]
:description "Liisa is a valid boss"
:address nil}
st/string-transformer)
; {::age 63
; :boss true
; :name "Liisa"
; :aliases [{:alias "Lissu"} "Liisu"]
; :languages #{:clj :cljs}
; :orders [{:id 1, :description "cola"}
; {:id 2, :description "kebab"}]
; :description "Liisa is a valid boss"
; :address nil}
A multimethod walk
taking a spec, value, accept function and options to walk over both specs and values. Used by coerce
, which transforms specs values using spec transformers.
A tool to walk over and transform specs using the Visitor-pattern. Main entry point is the spec-tools.visitor/visit
function, extendable via spec-tools.visitor/visit-spec
multimethod. There is an example implementation for recursively collecting nested specs. Also, the Spec to JSON Schema -converter is implemented using the visitor.
(require '[spec-tools.visitor :as visitor])
;; visitor to recursively collect all registered spec forms
(let [specs (atom {})]
(visitor/visit
person-spec
(fn [_ spec _ _]
(if-let [s (s/get-spec spec)]
(swap! specs assoc spec (s/form s))
@specs))))
; {:user/id ..
; :user/age ..
; :user$person/boss ..
; :user$person/name ..
; :user$person/aliases ..
; :user$person/languages ..
; :user$person/aliases
; :user$person$aliases$maps/alias
; :user$person$orders/id ..
; :user$person$orders/description ..
; :user$person/orders ..
; :user$person$address/street ..
; :user$person$address/zip ..
; :user$person/address ..
; :user$person/description ..}
NOTE: due to CLJ-2152, s/&
& s/keys*
can't be visited.
Generating JSON Schemas from arbitrary specs (and Spec Records).
(require '[spec-tools.json-schema :as jsc])
(jsc/transform person-spec)
; {:type "object"
; :properties {"user/id" {:type "integer"}
; "user/age" {:type "integer", :format "int64", :minimum 1}
; "boss" {:type "boolean"}
; "name" {:type "string"}
; "aliases" {:type "array",
; :items {:anyOf [{:type "string"}
; {:type "object",
; :properties {"alias" {:type "string"}},
; :required ["alias"]}]}},
; "languages" {:type "array", :items {:type "string"}, :uniqueItems true}
; "orders" {:type "array"
; :items {:type "object"
; :properties {"id" {:type "integer", :format "int64"}
; "description" {:type "string"}}
; :required ["id" "description"]}}
; "address" {:oneOf [{:type "object"
; :properties {"street" {:type "string"}
; "zip" {:type "string"}}
; :required ["street" "zip"]}
; {:type "null"}]}
; "description" {:type "string"}}
; :required ["user/id" "user/age" "boss" "name" "languages" "orders" "address"]}
Extra data from Spec records is used to populate the data:
(jsc/transform
(st/spec
{:spec integer?
:name "integer"
:description "it's an int"
:json-schema/default 42}))
; {:type "integer"
; :title "integer"
; :description "it's an int"
; :default 42}
A converter from Specs to Swagger2 (JSON) Schemas. Can be used as standalone but will be later available as ring-swagger module. See https://github.com/metosin/ring-swagger/issues/95.
(require '[spec-tools.swagger.core :as swagger])
swagger/transform
converts specs into Swagger2 JSON Schema. Transformation can be customized with the following optional options:
:type
- a target type, either :parameter
(Parameter Object) or :schema
(Schema Object). If value is not defined, :schema
is assumed.:in
- a parameter subtype, which is one of: :query
, :header
, :path
, :body
or :formData
. See Parameter Object for details.NOTE: As clojure.spec
is more powerful than the Swagger2 JSON Schema, we are losing some data in the transformation. We try to retain all the informatin, via vendor extensions.
(swagger/transform float?)
; {:type "number" :format "float"}
;; no "null" in swagger2
(swagger/transform (s/nilable string?))
; {:type "string", :x-nullable true}
;; swagger2 parameter syntax
(swagger/transform (s/nilable string?) {:type :parameter})
; {:type "string", :allowEmptyValue true}
;; no "anyOf" in swagger2
(swagger/transform (s/cat :int integer? :string string?))
; {:type "array"
; :items {:type "integer"
; :x-anyOf [{:type "integer"}
; {:type "string"}]}}
swagger/swagger-spec
function takes an extended swagger2 spec as map and transforms it into a valid Swagger Object. Rules:
swagger/expand
multimethod is invoked with the key, value and the map as arguments
::swagger/extension
Predifined dispatch keys below.
::swagger/parameters
Value should be a map with optional keys :body
, :query
, :path
, :header
and :formData
. For all but :body
, the value should be a s/keys
spec (describing the ring parameters). With :body
, the value can be any clojure.spec.alpha/Spec
.
Returns a map with key :parameters
with value of vector of swagger Parameter Objects, merged over the existing :parameters
. Duplicate parameters (with identical :in
and :name
are overridden)
(swagger/swagger-spec
{:paths
{"echo"
{:post
{:parameters
[;; existing parameter, will be overriddden
{:in "query"
:name "name"
:required false}
;; unique parameter, will remain
{:in "query"
:name "name2"
:type "string"
:required true}]
;; the spec-parameters
::swagger/parameters
{:query (s/keys :opt-un [::name])
:body ::user}}}}})
; {:paths
; {"echo"
; {:post
; {:parameters
; [{:in "query"
; :name "name2"
; :description "merged"
; :type "string"
; :required true}
; {:in "query"
; :name ""
; :description ""
; :type "string"
; :required false}
; {:in "body"
; :name ""
; :description ""
; :required true
; :schema {:type "object"
; :title "user/user"
; :properties {"name" {:type "string"}}
; :required ["name"]}}]}}}}
::swagger/responses
Value should a Swagger2 Responses Definition Object with Spec or Spec as the :schema
. Returns a map with key :responses
with :schemas
transformed into Swagger2 Schema Objects, merged over existing :responses
.
(s/def ::name string?)
(s/def ::user (s/keys :req-un [::name]))
(swagger/swagger-spec
{:responses {404 {:description "fail"}
500 {:description "fail"}}
::swagger/responses
{200 {:schema ::user
:description "Found it!"}
404 {:description "Ohnoes."}}})
; {:responses
; {200 {:schema
; {:type "object",
; :properties {"name" {:type "string"}},
; :required ["name"],
; :title "user/user"},
; :description "Found it!"}
; 404 {:description "Ohnoes."
; :schema {}},
; 500 {:description "fail"}}}
(require '[spec-tools.swagger.core :as swagger])
(require '[clojure.spec.alpha :as s])
(s/def ::id string?)
(s/def ::name string?)
(s/def ::street string?)
(s/def ::city #{:tre :hki})
(s/def ::address (s/keys :req-un [::street ::city]))
(s/def ::user (s/keys :req-un [::id ::name ::address]))
(swagger/swagger-spec
{:swagger "2.0"
:info {:version "1.0.0"
:title "Sausages"
:description "Sausage description"
:termsOfService "http://helloreverb.com/terms/"
:contact {:name "My API Team"
:email "foo@example.com"
:url "http://www.metosin.fi"}
:license {:name "Eclipse Public License"
:url "http://www.eclipse.org/legal/epl-v10.html"}}
:tags [{:name "user"
:description "User stuff"}]
:paths {"/api/ping" {:get {:responses {:default {:description ""}}}}
"/user/:id" {:post {:summary "User Api"
:description "User Api description"
:tags ["user"]
::swagger/parameters {:path (s/keys :req [::id])
:body ::user}
::swagger/responses {200 {:schema ::user
:description "Found it!"}
404 {:description "Ohnoes."}}}}}})
; {:swagger "2.0",
; :info {:version "1.0.0",
; :title "Sausages",
; :description "Sausage description",
; :termsOfService "http://helloreverb.com/terms/",
; :contact {:name "My API Team", :email "foo@example.com", :url "http://www.metosin.fi"},
; :license {:name "Eclipse Public License", :url "http://www.eclipse.org/legal/epl-v10.html"}},
; :tags [{:name "user", :description "User stuff"}],
; :paths {"/api/ping" {:get {:responses {:default {:description ""}}}},
; "/user/:id" {:post {:summary "User Api",
; :description "User Api description",
; :tags ["user"],
; :responses {200 {:description "Found it!",
; :schema {:type "object",
; :properties {"id" {:type "string"},
; "name" {:type "string"},
; "address" {:type "object",
; :properties {"street" {:type "string"},
; "city" {:enum [:tre :hki]}},
; :required ["street" "city"]}},
; :required ["id" "name" "address"]}},
; 404 {:description "Ohnoes."}},
; :x-spec-tools.swagger.core-test/kikka 42,
; :parameters [{:in "path", :name "", :description "", :type "string", :required true}
; {:in "body",
; :name "",
; :description "",
; :required true,
; :schema {:type "object",
; :properties {"id" {:type "string"},
; "name" {:type "string"},
; "address" {:type "object",
; :properties {"street" {:type "string"},
; "city" {:enum [:tre :hki]}},
; :required ["street" "city"]}},
; :required ["id" "name" "address"]}}]}}}}
TODO
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Distributed under the Eclipse Public License, the same as Clojure.
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