Support for rdf:XMLLiterals in XML decoder

Thanks @doughsay for the hint on kbrw/sweet_xml#45
in kbrw/sweet_xml#58

lib/sparql/query/result/formats/xml_decoder.ex

@@ -80,8 +80,7 @@ defmodule SPARQL.Query.Result.XML.Decoder do
         node |> xpath(~x"./text()"s) |> RDF.Literal.new(language: language)
       (datatype = xpath(node, ~x"./@datatype"s)) ==
           "http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral" ->
-        require IEx ; IEx.pry
-        node |> xpath(~x"./text()"s) |> RDF.Literal.new(datatype: datatype)
+        node |> xpath(~x"*") |> node_to_xml() |> RDF.Literal.new(datatype: datatype)
       (datatype = xpath(node, ~x"./@datatype"s)) != "" ->
         node |> xpath(~x"./text()"s) |> RDF.Literal.new(datatype: datatype)
       true ->
@@ -95,4 +94,13 @@ defmodule SPARQL.Query.Result.XML.Decoder do
   defp decode_value(value),
     do: raise "Invalid query result: #{inspect node}"
 
+  # TODO: This is quite hacky! Is there a better solution? - https://github.com/kbrw/sweet_xml/issues/58
+  # TODO: Remove this when https://github.com/kbrw/sweet_xml/pull/45 gets merged
+  defp node_to_xml(node) do
+    [node]
+    |> :xmerl.export(:xmerl_xml)
+    |> List.flatten()
+    |> List.to_string()
+    |> String.replace_leading(~s[<?xml version="1.0"?>], "")
+  end
 end

test/sparql/query/result/xml_decoder_test.exs

@@ -175,7 +175,6 @@ defmodule SPARQL.Query.Result.XML.DecoderTest do
                   ]}}
   end
 
-  @tag skip: "TODO"
   test "SELECT result with rdf:XMLLiteral" do
     assert Query.Result.XML.decode("""
         <sparql xmlns="http://www.w3.org/2005/sparql-results#" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3.org/2001/sw/DataAccess/rf1/result2.xsd">
@@ -193,7 +192,7 @@ defmodule SPARQL.Query.Result.XML.DecoderTest do
           </results>
         </sparql>
         """) == {:ok, %Query.ResultSet{
-                  variables: ~w[x hpage name mbox age blurb friend],
+                  variables: ~w[blurb],
                   results: [
                     %Query.Result{bindings: %{
                       "blurb"  => RDF.Literal.new(