AgentSkillsCN

clojure-malli

在 Clojure 中利用 Malli Schema 进行数据校验。当您需要：(0) Malli，(1) 实施数据校验或强制转换；(2) 为映射、集合，或领域模型定义 Schema；(3) 验证 API 请求/响应；(4) 进行表单校验；(5) 执行运行时类型检查，或当用户提及 Malli、Schema、校验、数据契约，或数据完整性时，均可使用此技能。

SKILL.md
--- frontmatter
name: clojure-malli
description: |
  Data validation with Malli schemas in Clojure. Use when working with: (0)
  malli, (1) data validation or coercion, (2) defining schemas for maps,
  collections, or domain models, (3) API request/response validation, (4) form
  validation, (5) runtime type checking, or when the user mentions malli,
  schemas, validation, data contracts, or data integrity.

Malli Data Validation

Malli validates data against schemas. Schemas are Clojure data structures.

Quick Validation

clojure
(require '[malli.core :as m])
(require '[malli.error :as me])

;; Validate
(m/validate [:map [:name :string] [:age :int]]
            {:name "Alice" :age 30})
;; => true

;; Get errors
(-> [:map [:name :string] [:age :int]]
    (m/explain {:name "Alice" :age "thirty"})
    (me/humanize))
;; => {:age ["should be an integer"]}

Quick Coercion

clojure
(require '[malli.transform :as mt])

;; Decode string input to proper types
(m/decode [:map [:port :int] [:active :boolean]]
          {:port "8080" :active "true"}
          (mt/string-transformer))
;; => {:port 8080, :active true}

;; Coerce = decode + validate (throws on error)
(m/coerce [:map [:id :int]] {:id "42"} (mt/string-transformer))
;; => {:id 42}

Common Schema Patterns

Maps with Required/Optional Keys

clojure
[:map
 [:id :uuid]                              ;; required
 [:name :string]                          ;; required
 [:email {:optional true} :string]        ;; optional
 [:role {:default "user"} :string]]       ;; optional with default

Constrained Values

clojure
[:string {:min 1 :max 100}]    ;; string length 1-100
[:int {:min 0 :max 150}]       ;; integer range
[:enum "draft" "published"]    ;; one of these values
[:re #".+@.+\..+"]             ;; regex match

Collections

clojure
[:vector :int]                 ;; vector of ints
[:set :keyword]                ;; set of keywords
[:map-of :keyword :string]     ;; map with keyword keys, string values
[:tuple :double :double]       ;; fixed [x, y] pair

Unions and Conditionals

clojure
;; Simple union
[:or :string :int]

;; Nilable
[:maybe :string]               ;; string or nil

;; Tagged union with dispatch
[:multi {:dispatch :type}
 [:user [:map [:type [:= :user]] [:name :string]]]
 [:admin [:map [:type [:= :admin]] [:role :string]]]]

Nested Structures

clojure
[:map
 [:user [:map
         [:name :string]
         [:address [:map
                    [:city :string]
                    [:zip :string]]]]]]

Performance: Cache Validators

clojure
;; BAD - creates validator every call
(defn process [data]
  (when (m/validate schema data) ...))

;; GOOD - cached validator
(def valid? (m/validator schema))
(defn process [data]
  (when (valid? data) ...))

;; Same for decoders
(def decode-request (m/decoder schema (mt/string-transformer)))
(def coerce-request (m/coercer schema (mt/string-transformer)))

Key Gotchas

  1. •decode doesn't validate - returns invalid data as-is. Use coerce for safety.
  2. •Maps are open by default - extra keys allowed. Use {:closed true} to reject them.
  3. •Keys are required by default - use {:optional true} for optional keys.

Detailed References