Dynamically Generate SQL

While there is nothing wrong with putting SQL in strings, many reasonable features will require you to dynamically produce those strings based on user input.

• Add honeysql to your deps.edn.

  {:paths ["src"]
   :deps {org.clojure/clojure {:mvn/version "1.12.0"}
          ring/ring {:mvn/version "1.13.0"}
          metosin/reitit-ring {:mvn/version "0.7.2"}
          org.clojure/tools.logging {:mvn/version "1.3.0"}
          org.slf4j/slf4j-simple {:mvn/version "2.0.16"}
          hiccup/hiccup {:mvn/version "2.0.0-RC3"}
          com.github.seancorfield/next.jdbc {:mvn/version "1.3.955"}
          org.postgresql/postgresql {:mvn/version "42.7.4"}
          com.zaxxer/HikariCP {:mvn/version "6.0.0"}
          io.github.cdimascio/dotenv-java {:mvn/version "3.0.2"}
          ring/ring-defaults {:mvn/version "0.5.0"}
          msolli/proletarian {:mvn/version "1.0.86-alpha"}
          cheshire/cheshire {:mvn/version "5.13.0"}
          com.github.seancorfield/honeysql {:mvn/version "2.6.1203"}}
   :aliases {:dev {:extra-paths ["dev" "test"]
                   :extra-deps {nrepl/nrepl {:mvn/version "1.3.0"}
                                lambdaisland/kaocha {:mvn/version "1.91.1392"}}}
             :format {:deps {dev.weavejester/cljfmt {:mvn/version "0.13.0"}}}
             :lint   {:deps {clj-kondo/clj-kondo {:mvn/version "2024.09.27"}}}}}

• Using honey.sql/format, replace the query for inserting hominids

  Nothing special about this one, but this example project doesn't have a killer use for dynamic SQL yet. It should suffice to show how it's done. Refer to honeysql's documentation for more info.

  (ns example.cave.jobs
    (:require [example.system :as-alias system]
              [honey.sql :as sql]
              [next.jdbc :as jdbc])
    (:import (java.util UUID)))
  
  (set! *warn-on-reflection* true)
  
  (defn process-cave-insert
    [{::system/keys [db]} _job-type payload]
    (jdbc/execute!
     db
     (sql/format
      {:insert-into :prehistoric/hominid
       :values [{:name    "Grunk"
                 :cave_id (UUID/fromString (:id payload))}]})))
  
  (defn handlers
    []
    {:prehistoric.cave/insert #'process-cave-insert})