footnotes: clean up logick

Author: tiberlas

src/docx/document.py

@@ -208,7 +208,7 @@ def _calculate_next_footnote_reference_id(self, p):
         new_fr_id = 1
         # If paragraph already contains footnotes
         # append the new footnote and the end with the next reference id.
-        if p.footnote_reference_ids is not None:
+        if len(p.footnote_reference_ids) > 0:
             new_fr_id = p.footnote_reference_ids[-1] + 1
         # Read the paragraphs containing footnotes and find where the
         # new footnote will be. Keeping in mind that the footnotes are
@@ -224,7 +224,7 @@ def _calculate_next_footnote_reference_id(self, p):
                 has_passed_containing_para = True
                 continue
             # Skip paragraphs without footnotes (they don't impact new id).
-            if self.paragraphs[p_i]._p.footnote_reference_ids is None:
+            if len(self.paragraphs[p_i]._p.footnote_reference_ids) == 0:
                 continue
             # These footnotes are after the new footnote, so we increment them.
             if not has_passed_containing_para:

src/docx/footnotes.py

@@ -35,7 +35,7 @@ def add_footnote(self, footnote_reference_id):
         """
         elements = self._element # for easy access
         new_footnote = None
-        if elements.get_by_id(footnote_reference_id):
+        if elements.get_by_id(footnote_reference_id) is not None:
             # When adding a footnote it can be inserted 
             # in front of some other footnotes, so
             # we need to sort footnotes by `footnote_reference_id`

src/docx/oxml/footnote.py

@@ -24,7 +24,7 @@ def add_footnote(self, footnote_reference_id):
         return new_f
 
     def get_by_id(self, id):
-        found = self.xpath('w:footnote[@w:id="%s"]' % id)
+        found = self.xpath(f'w:footnote[@w:id="{id}"]')
         if not found:
             return None
         return found[0]
@@ -56,6 +56,4 @@ def paragraphs(self):
         for child in self:
             if child.tag == qn('w:p'):
                 paragraphs.append(child)
-        if paragraphs == []:
-            paragraphs = None
         return paragraphs

src/docx/oxml/section.py

@@ -248,7 +248,7 @@ def footnote_number_format(self):
         attribute is not present.
         """
         fPr = self.footnotePr
-        if fPr is None or fPr.numFmt:
+        if fPr is None or fPr.numFmt is None:
             return None
         return fPr.numFmt.val
 
@@ -266,7 +266,7 @@ def footnote_numbering_restart_location(self):
         attribute is not present.
         """
         fPr = self.footnotePr
-        if fPr is None or fPr.numRestart:
+        if fPr is None or fPr.numRestart is None:
             return None
         return fPr.numRestart.val
 
@@ -291,7 +291,7 @@ def footnote_numbering_start_value(self):
         attribute is not present.
         """
         fPr = self.footnotePr
-        if fPr is None or fPr.numStart:
+        if fPr is None or fPr.numStart is None:
             return None
         return fPr.numStart.val
 

src/docx/oxml/text/paragraph.py

@@ -81,8 +81,6 @@ def footnote_reference_ids(self):
             new_footnote_ids = run.footnote_reference_ids
             if new_footnote_ids:
                 footnote_ids.extend(new_footnote_ids)
-        if footnote_ids == []:
-            footnote_ids = None
         return footnote_ids
 
     def set_sectPr(self, sectPr: CT_SectPr):

src/docx/text/paragraph.py

@@ -95,11 +95,9 @@ def footnotes(self):
         Returns a list of |Footnote| instances that refers to the footnotes in this paragraph,
         or |None| if none footnote is defined.
         """
+        footnote_list = []
         reference_ids = self._p.footnote_reference_ids
-        if reference_ids == None:
-            return None
         footnotes = self._parent._parent.footnotes
-        footnote_list = []
         for ref_id in reference_ids:
             footnote_list.append(footnotes[ref_id])
         return footnote_list