Fix handling of xdata in bibtex/biblatex bibliographies.

Closes #6752.

src/Text/Pandoc/Citeproc/BibTeX.hs

@@ -61,7 +61,8 @@ readBibtexString :: Variant           -- ^ bibtex or biblatex
 readBibtexString variant locale idpred contents = do
   case runParser (((resolveCrossRefs variant <$> bibEntries) <* eof) >>=
                    mapM (itemToReference locale variant) .
-                      filter (idpred . identifier))
+                      filter (\item -> idpred (identifier item) &&
+                                        entryType item /= "xdata"))
            (fromMaybe defaultLang $ localeLanguage locale, Map.empty)
            "" contents of
           Left err -> Left err
@@ -1058,7 +1059,6 @@ getTypeAndGenre :: Bib (Text, Maybe Text)
 getTypeAndGenre = do
   lang <- gets localeLang
   et <- asks entryType
-  guard $ et /= "xdata"
   reftype' <- resolveKey' lang <$> getRawField "type"
          <|> return mempty
   st <- getRawField "entrysubtype" <|> return mempty

test/command/6752.md

@@ -0,0 +1,36 @@
+```
+% pandoc -f biblatex -t csljson
+@xdata{XDPubAlfredAKnopf,
+    publisher   = {Alfred A.~Knopf},
+    address     = {New York, NY}
+}
+@book{Klinkenborg2012,
+    author      = {Verlyn Klinkenborg},
+    title       = {Several short sentences about writing},
+    date        = {2012},
+    xdata       = {XDPubAlfredAKnopf},
+}
+^D
+[
+  {
+    "author": [
+      {
+        "family": "Klinkenborg",
+        "given": "Verlyn"
+      }
+    ],
+    "id": "Klinkenborg2012",
+    "issued": {
+      "date-parts": [
+        [
+          2012
+        ]
+      ]
+    },
+    "publisher": "Alfred A. Knopf",
+    "publisher-place": "New York, NY",
+    "title": "Several short sentences about writing",
+    "type": "book"
+  }
+]
+```