fix: fix no journal name in Semanticscholar and underscore in DOIs (#69)

Author: njzjz

wenxian/feeder/semanticscholar.py

@@ -30,7 +30,7 @@ def _from_identifier(self, identifier: str) -> Reference | None:
             authors.append(Author(first=first, last=last))
         # journal may be null, e.g.,
         # https://api.semanticscholar.org/graph/v1/paper/10.1103/PhysRevB.109.174106?fields=title,year,abstract,authors.name,journal,externalIds
-        if res["journal"] is not None:
+        if res["journal"] is not None and "name" in res["journal"]:
             journal = res["journal"]["name"]
             # the journal might be HTML escaped, e.g., Journal of Materials Science & Technology
             # https://api.semanticscholar.org/graph/v1/paper/10.1016/j.jmst.2023.09.059?fields=title,year,abstract,authors.name,journal,externalIds

wenxian/reference.py

@@ -207,6 +207,10 @@ def bibtex(self) -> str:
                     # prevent {} in author that is used to split first and last name
                     # be escaped
                     valuestr = valuestr.replace(r"{\{}", r"{").replace(r"{\}}", r"}")
+                if key == "doi":
+                    # for DOI, underscore should not be escaped
+                    # https://tex.stackexchange.com/questions/550123/underscore-in-doi-in-bibtex-file
+                    valuestr = valuestr.replace(r"{\_}", r"_")
                 if key == "title":
                     valuestr = f"{{{{{valuestr}}}}}"
                 else: