MySQL on NodeJS

[Jonathon McKitrick]

Hi all,

I'm slowly but surely weaseling Clojure and Clojurescript into our company's codebase. I'm tasked with a script which will read from a MySQL database and generate a very simple report.

So far, I have a NodeJS REPL project up and running, but I'm not quite sure how to get Node's MySQL library into the project and namespace. Any thoughts?

[Jonathon McKitrick]

Here's what I have so far:

(defproject foo "0.1.0-SNAPSHOT"

  :description "FIXME"

  

  :dependencies [[org.clojure/clojure "1.8.0"]

                 [org.clojure/clojurescript "1.9.908"]

                 [com.cemerick/piggieback "0.2.2"]]

  :plugins [[lein-cljsbuild "1.1.7"]

            [lein-ancient "0.6.12"]]

  :repl-options {:nrepl-middleware [cemerick.piggieback/wrap-cljs-repl]}

  :source-paths ["src"]

  :cljsbuild

  {:builds

   [{:source-paths ["src"]

     :compiler

     {:target :nodejs

      :output-to "check_templates.js"

      :optimizations :none

      :npm-deps {:mysql "2.14.1"}

      :install-deps true

      :main check-templates.core

      :parallel-build true}}]})

and

(ns check-templates.core

  (:require [cljs.nodejs :as nodejs]

            #_[mysql :as sql]))

(nodejs/enable-util-print!)

(defn -main [& args]

  (.log js/console "Hello world")

  (println "Hello world"))

(set! *main-cli-fn* -main)

I run `lein cljsbuild once` and I get the node_modules directory populated with dependencies.

I can run `lein repl` and then use piggieback to get to the CLJS repl. But I seem unable to get the mysql dependency imported.

If I enable the `require` form to import mysql in the source file and then start the repl and require the project namespace, I get this error:

events.js:160

      throw er; // Unhandled 'error' event

      ^

Error: Can't resolve 'url' in '/Users/devmbp42/arc/check-templates/node_modules/mysql/lib'

    at onError (/Users/devmbp42/arc/check-templates/node_modules/enhanced-resolve/lib/Resolver.js:61:15)

So it's finding the modules and attempting to load them. But I don't know enough about NodeJS to understand exactly what is broken or how to fix it.

[Jonathon McKitrick]

Update: it turns out several of the dependencies of mysql had to be imported at the project level. At least, that's what I did to get past the dependency errors. Now I'm stuck here:

path.js:7

    throw new TypeError('Path must be a string. Received ' + inspect(path));

    ^

TypeError: Path must be a string. Received { './support/isBuffer.js': './support/isBufferBrowser.js' }

    at assertPath (path.js:7:11)

    at Object.join (path.js:1211:7)

    at Deps.<anonymous> ([eval]:115:32)

    at emitOne (events.js:96:13)

    at Deps.emit (events.js:188:7)

    at /Users/devmbp42/arc/check-templates/node_modules/@cljs-oss/module-deps/index.js:338:18

It looks like I got past the dependency issues, but I'm not sure where to go from here....

[Jonathon McKitrick]

So I've come to the conclusion that the REPL and CIDER do not pick up any of the NodeJS namespaces. I have to build the project and run it with node instead. Not sure exactly why this is the case....

[Phill Wolf]

Are you using Figwheel with Node?

Your project sounds ambitious.  If your program must connect to MySQL, perhaps you could use the real (JVM) Clojure instead with less bother.  But I imagine you have your reasons for jousting with ClojureScript-on-Node-with-nREPL-and-CIDER.  At any rate, it makes good reading, so I look forward to the next installment.

[jmcki...@gmail.com]

I'm not using Figwheel with Node, though that sounds like a good next step since CIDER isn't picking up the NodeJS imports.

I decided to try NodeJS since it has a lot of support around the office, and this is a script which should have a short startup time. So far, so good.

On Mon, Sep 25, 2017 at 7:32 PM Phill Wolf <phill...@gmail.com> wrote:

Are you using Figwheel with Node?

Your project sounds ambitious.  If your program must connect to MySQL, perhaps you could use the real (JVM) Clojure instead with less bother.  But I imagine you have your reasons for jousting with ClojureScript-on-Node-with-nREPL-and-CIDER.  At any rate, it makes good reading, so I look forward to the next installment.

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Jonathon McKitrick

[Kinley Dorji]

Have you tried Lumo? Might be worth a shot.