xmlclojuretype-conversionconvertersedn

How to convert XML to edn in Clojure?


I'm new to Clojure and would like to convert an XML I have into an edn object.

The XML file I reads:

<Vehicle>
  <Model>Toyota</Model>
  <Color>Red</Color>
  <Loans>
    <Reoccuring>Monthly</Reoccuring>
    <Owners>
      <Owner>Bob</Owner>
    </Owners>
  </Loans>
  <Tires>
    <Model>123123</Model>
    <Size>23</Size>
  </Tires>
  <Engine>
    <Model>30065</Model>
  </Engine>
</Vehicle>

And I have saved it as 'test/resources/vehicle.xml

Ultimately, I would like to have a EDN object that looks like:

:Vehicle
    :Model "Toyota"
    :Color "Red"
    :Loans
        :Reoccuring "Monthly"
        :Owners
            :Owner "Bob"
    :Tires
        :Model 123123
        :Size 23
    :Engine
        :Model 30065

So far, what I have tried in Clojure is the parse method:

(def xml-parser
  (parse "<Vehicle><Model>Toyota</Model><Color>Red</Color><Loans><Reoccuring>Monthly</Reoccuring><Owners><Owner>Bob</Owner></Owners></Loans><Tires><Model>123123</Model><Size>23</Size></Tires><Engine><Model>30065</Model></Engine></Vehicle>"))

However, this returns a Clojure hash that looks like:

{:tag :Vehicle, :attrs nil, :content [{:tag :Model, :attrs nil, :content ["Toyota"]} {:tag :Color, :attrs nil, :content ["Red"]} {:tag :Loans, :attrs nil, :content [{:tag :Reoccuring, :attrs nil, :content ["Monthly"]} {:tag :Owners, :attrs nil, :content [{:tag :Owner, :attrs nil, :content ["Bob"]}]}]} {:tag :Tires, :attrs nil, :content [{:tag :Model, :attrs nil, :content ["123123"]} {:tag :Size, :attrs nil, :content ["23"]}]} {:tag :Engine, :attrs nil, :content [{:tag :Model, :attrs nil, :content ["30065"]}]}]}

I'm having trouble with this initial step of conversion. Thank you for your help in advance.


Solution

  • The data you have is in Enlive format. Use clojure.pprint/pprint to see a nicer format:

    {:tag :Vehicle,
     :attrs nil,
     :content
     [{:tag :Model, :attrs nil, :content ["Toyota"]}
      {:tag :Color, :attrs nil, :content ["Red"]}
      {:tag :Loans,
       :attrs nil,
       :content
       [{:tag :Reoccuring, :attrs nil, :content ["Monthly"]}
        {:tag :Owners,
         :attrs nil,
         :content [{:tag :Owner, :attrs nil, :content ["Bob"]}]}]}
      {:tag :Tires,
       :attrs nil,
       :content
       [{:tag :Model, :attrs nil, :content ["123123"]}
        {:tag :Size, :attrs nil, :content ["23"]}]}
      {:tag :Engine,
       :attrs nil,
       :content [{:tag :Model, :attrs nil, :content ["30065"]}]}]}
    

    The problem is that your desired output is not actually legal EDN data format. However, you can use the tupelo.forest library to convert among several data formats:

    First declare the data and parse it into Enlive format:

    (ns tst.demo.core
      (:use tupelo.core tupelo.test)
      (:require
        [tupelo.parse.xml :as xml]
        [tupelo.forest :as tf])
      )
    
    (def xml-str
       "<Vehicle>
          <Model>Toyota</Model>
          <Color>Red</Color>
          <Loans>
            <Reoccuring>Monthly</Reoccuring>
            <Owners>
              <Owner>Bob</Owner>
            </Owners>
          </Loans>
          <Tires>
            <Model>123123</Model>
            <Size>23</Size>
          </Tires>
          <Engine>
            <Model>30065</Model>
          </Engine>
        </Vehicle> ")
    

    verify the result

    (dotest
      (let [data-enlive (xml/parse xml-str)]
        (is= data-enlive
          {:tag     :Vehicle,
           :attrs   {},
           :content [{:tag :Model, :attrs {}, :content ["Toyota"]}
                     {:tag :Color, :attrs {}, :content ["Red"]}
                     {:tag     :Loans,
                      :attrs   {},
                      :content [{:tag :Reoccuring, :attrs {}, :content ["Monthly"]}
                                {:tag     :Owners,
                                 :attrs   {},
                                 :content [{:tag :Owner, :attrs {}, :content ["Bob"]}]}]}
                     {:tag     :Tires,
                      :attrs   {},
                      :content [{:tag :Model, :attrs {}, :content ["123123"]}
                                {:tag :Size, :attrs {}, :content ["23"]}]}
                     {:tag     :Engine,
                      :attrs   {},
                      :content [{:tag :Model, :attrs {}, :content ["30065"]}]}]})
    

    convert to Hiccup format:

        (is= (tf/enlive->hiccup data-enlive)
          [:Vehicle
           [:Model "Toyota"]
           [:Color "Red"]
           [:Loans [:Reoccuring "Monthly"]
            [:Owners [:Owner "Bob"]]]
           [:Tires [:Model "123123"]
            [:Size "23"]]
           [:Engine [:Model "30065"]]])
    

    You may also like the "bush" format:

        (is= (tf/enlive->bush data-enlive)
          [{:tag :Vehicle}
           [{:tag :Model, :value "Toyota"}]
           [{:tag :Color, :value "Red"}]
           [{:tag :Loans}
            [{:tag :Reoccuring, :value "Monthly"}]
            [{:tag :Owners} [{:tag :Owner, :value "Bob"}]]]
           [{:tag :Tires}
            [{:tag :Model, :value "123123"}]
            [{:tag :Size, :value "23"}]]
           [{:tag :Engine} [{:tag :Model, :value "30065"}]]])
    

    or the more detailed "tree" format

        (is= (tf/enlive->tree data-enlive)
          {:tag :Vehicle,
           :tupelo.forest/kids
                [{:tag :Model, :value "Toyota", :tupelo.forest/kids []}
                 {:tag :Color, :value "Red", :tupelo.forest/kids []}
                 {:tag :Loans,
                  :tupelo.forest/kids
                       [{:tag :Reoccuring, :value "Monthly", :tupelo.forest/kids []}
                        {:tag :Owners,
                         :tupelo.forest/kids
                              [{:tag :Owner, :value "Bob", :tupelo.forest/kids []}]}]}
                 {:tag :Tires,
                  :tupelo.forest/kids
                       [{:tag :Model, :value "123123", :tupelo.forest/kids []}
                        {:tag :Size, :value "23", :tupelo.forest/kids []}]}
                 {:tag :Engine,
                  :tupelo.forest/kids
                       [{:tag :Model, :value "30065", :tupelo.forest/kids []}]}]})
        ))
    

    See the Tupelo Forest docs for full information.


    The above code was run using this template project.


    If you are looking for a hierarchical map style output, you can kludge together something like so:

    (ns tst.demo.core
      (:use tupelo.core tupelo.test)
      (:require [clojure.walk :as walk]))
    
    (dotest
      (let [data  [:Vehicle
                   [:Model "Toyota"]
                   [:Color "Red"]
                   [:Loans
                    [:Reoccuring "Monthly"]
                    [:Owners
                     [:Owner "Bob"]]]
                   [:Tires
                    [:Model "123123"]
                    [:Size "23"]]
                   [:Engine
                    [:Model "30065"]]]
    
            mappy (walk/postwalk
                    (fn [item]
                      (if (vector? item)
                        (if (= 2 (count item))
                          (conj {} item)
                          {(first item)
                           (into {} (rest item))})
                        item))
                    data)]
    

    with test

        (is= mappy
          {:Vehicle
           {:Model  "Toyota",
            :Color  "Red",
            :Loans  {:Reoccuring "Monthly"
                     :Owners     {:Owner "Bob"}},
            :Tires  {:Model "123123"
                     :Size  "23"},
            :Engine {:Model "30065"}}})))
    

    Although this is pretty fragile as written.