Fix column wrapping breaking with None values (fixes #312)

pyproject.toml

@@ -32,8 +32,8 @@ widechars = ["wcwidth"]
 [project.scripts]
 tabulate = "tabulate:_main"
 
-[tool.setuptools]
-packages = ["tabulate"]
+# [tool.setuptools]
+# packages = ["tabulate"]
 
-[tool.setuptools_scm]
-write_to = "tabulate/version.py"
+# [tool.setuptools_scm]
+# write_to = "tabulate/version.py"

tabulate/__init__.py

@@ -1638,7 +1638,7 @@ def _normalize_tabular_data(tabular_data, headers, showindex="default"):
     return rows, headers, headers_pad
 
 
-def _wrap_text_to_colwidths(list_of_lists, colwidths, numparses=True, break_long_words=_BREAK_LONG_WORDS, break_on_hyphens=_BREAK_ON_HYPHENS):
+def _wrap_text_to_colwidths(list_of_lists, colwidths, numparses=True, missingval=_DEFAULT_MISSINGVAL, break_long_words=_BREAK_LONG_WORDS, break_on_hyphens=_BREAK_ON_HYPHENS):
     if len(list_of_lists):
         num_cols = len(list_of_lists[0])
     else:
@@ -1656,7 +1656,13 @@ def _wrap_text_to_colwidths(list_of_lists, colwidths, numparses=True, break_long
 
             if width is not None:
                 wrapper = _CustomTextWrap(width=width, break_long_words=break_long_words, break_on_hyphens=break_on_hyphens)
-                casted_cell = str(cell)
+                # Cast based on our internal type handling. Any future custom
+                # formatting of types (such as datetimes) may need to be more
+                # explicit than just `str` of the object. Also doesn't work for
+                # custom floatfmt/intfmt, nor with any missing/blank cells.
+                casted_cell = (
+                    missingval if cell is None else str(cell) if cell == '' or _isnumber(cell) else _type(cell, numparse)(cell)
+                )
                 wrapped = [
                     "\n".join(wrapper.wrap(line))
                     for line in casted_cell.splitlines()
@@ -2258,7 +2264,7 @@ def tabulate(
 
         numparses = _expand_numparse(disable_numparse, num_cols)
         list_of_lists = _wrap_text_to_colwidths(
-            list_of_lists, maxcolwidths, numparses=numparses, break_long_words=break_long_words, break_on_hyphens=break_on_hyphens
+            list_of_lists, maxcolwidths, numparses=numparses, missingval=missingval, break_long_words=break_long_words, break_on_hyphens=break_on_hyphens
         )
 
     if maxheadercolwidths is not None:
@@ -2272,7 +2278,7 @@ def tabulate(
 
         numparses = _expand_numparse(disable_numparse, num_cols)
         headers = _wrap_text_to_colwidths(
-            [headers], maxheadercolwidths, numparses=numparses, break_long_words=break_long_words, break_on_hyphens=break_on_hyphens
+            [headers], maxheadercolwidths, numparses=numparses, missingval=missingval, break_long_words=break_long_words, break_on_hyphens=break_on_hyphens
         )[0]
 
     # empty values in the first column of RST tables should be escaped (issue #82)

test/test_textwrapper.py

@@ -222,6 +222,50 @@ def test_wrap_datetime():
     assert_equal(expected, result)
 
 
+def test_wrap_none_value():
+    """TextWrapper: Show that None can be wrapped without crashing"""
+    data = [["First Entry", None], ["Second Entry", None]]
+    headers = ["Title", "Value"]
+    result = tabulate(data, headers=headers, tablefmt="grid", maxcolwidths=[7, 5])
+
+    expected = [
+        "+---------+---------+",
+        "| Title   | Value   |",
+        "+=========+=========+",
+        "| First   |         |",
+        "| Entry   |         |",
+        "+---------+---------+",
+        "| Second  |         |",
+        "| Entry   |         |",
+        "+---------+---------+",
+    ]
+    expected = "\n".join(expected)
+    assert_equal(expected, result)
+
+
+def test_wrap_none_value_with_missingval():
+    """TextWrapper: Show that None can be wrapped without crashing and with a missing value"""
+    data = [["First Entry", None], ["Second Entry", None]]
+    headers = ["Title", "Value"]
+    result = tabulate(
+        data, headers=headers, tablefmt="grid", maxcolwidths=[7, 5], missingval="???"
+    )
+
+    expected = [
+        "+---------+---------+",
+        "| Title   | Value   |",
+        "+=========+=========+",
+        "| First   | ???     |",
+        "| Entry   |         |",
+        "+---------+---------+",
+        "| Second  | ???     |",
+        "| Entry   |         |",
+        "+---------+---------+",
+    ]
+    expected = "\n".join(expected)
+    assert_equal(expected, result)      
+
+
 def test_wrap_optional_bool_strs():
     """TextWrapper: Show that str bools and None can be wrapped without crashing"""
     data = [