I am having trouble with unnest_wider (from tidyr).
I have this nested XML document that I am trying to convert into a dataframe/tibble. I followed the workflow presented here, which proposes to turn the XML nodeset into R lists.

My XML is OAI/Dublin Core formatted, and I have several elements in it that have the same name (“subject.other”, for example). Simplified, my doc.xml looks like this :

<?xml version="1.0" encoding="utf-8"?>
<ListRecords>
  <record>
    <header>
      <identifier>id_01</identifier>
      <datestamp>2024-05</datestamp>
    </header>
    <metadata>
      <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
        <dc:publisher>Fake Editions</dc:publisher>
        <dc:subject.other>Great subject n°1</dc:subject.other>
        <dc:subject.other>Great subject n°2</dc:subject.other>
        <dc:subject.other>Great subject n°3</dc:subject.other>
        <dc:subject.other>Great subject n°4</dc:subject.other>
        <dc:subject.other>Great subject n°5</dc:subject.other>
        <dc:subject.other>Great subject n°6</dc:subject.other>
        <dc:title>Random title</dc:title>
      </oai_dc:dc>
    </metadata>
  </record>
</ListRecords>

What I tried

The code that I ran is the following :

# doc.xml is turned into a list
doc_list <- xmlconvert::xml_to_list(read_xml("doc.xml")) 

# the list becomes a tibble
df <- tibble::enframe(doc_list) 

# unnesting the column "value", where we find the listed elements contained in <header> and <metadata> in the XML
final_df <- df %>%
  unnest_wider(value, names_repair = "universal") 

Expectations…

What I would like my final_df to look like in the end is something like that :

structure(list(
  identifier = "id_01",
  publisher = "Fake Editions", 
  subject.other_1 = "Great subject n°1",
  subject.other_2 = "Great subject n°2", 
  subject.other_3 = "Great subject n°3"), 
  class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, -1L))

…reality

But what I get is :

structure(list(
  identifier = "id_01",
  publisher = "Fake Editions", 
  subject.other_1 = "Great subject n°1",
  subject.other_2 = "Great subject n°1", 
  subject.other_3 = "Great subject n°1"), 
  class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, -1L))

As you can see, what happens is that the actual values contained in the different “subject.other” elements get erased and replaced by the value contained in the first one (“Great subject n°1”). I tried changing the .names_repair options, but it didn’t change anything.

Would you see any solution to make it work ? I have tried everything to get this XML into a dataframe/tibble, and I am losing hope !
Thank you very much !

(I can provide more code/details, sorry I am not used to asking questions on Stackoverflow)