Fixed #373 - Properly detect xlsx format

5 files changed, 19 insertions, 4 deletions

diff --git a/HISTORY.md b/HISTORY.md
index d5be2c4..2d92422 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -6,6 +6,7 @@
 - Fixed `DataBook().load` parameter ordering (first stream, then format).
 - Fixed a regression for xlsx exports where non-string values were forced to
   strings (#314).
+- Fixed xlsx format detection (which was often detected as `xls` format).
 - Added search to all documentation pages
 - Open xlsx workbooks in read-only mode (#316)
 - Unpin requirements
diff --git a/tablib/formats/__init__.py b/tablib/formats/__init__.py
index 418e607..52cf472 100644
--- a/tablib/formats/__init__.py
+++ b/tablib/formats/__init__.py
@@ -17,4 +17,5 @@ from . import _df as df
 from . import _rst as rst
 from . import _jira as jira
 
-available = (json, xls, yaml, csv, dbf, tsv, html, jira, latex, xlsx, ods, df, rst)
+# xlsx before as xls (xlrd) can also read xlsx
+available = (json, xlsx, xls, yaml, csv, dbf, tsv, html, jira, latex, ods, df, rst)
diff --git a/tablib/formats/_json.py b/tablib/formats/_json.py
index a794a3d..009fb3c 100644
--- a/tablib/formats/_json.py
+++ b/tablib/formats/_json.py
@@ -55,5 +55,5 @@ def detect(stream):
     try:
         json.loads(stream)
         return True
-    except ValueError:
+    except (TypeError, ValueError):
         return False
diff --git a/tablib/formats/_xlsx.py b/tablib/formats/_xlsx.py
index 6662a2f..516191c 100644
--- a/tablib/formats/_xlsx.py
+++ b/tablib/formats/_xlsx.py
@@ -22,8 +22,11 @@ extensions = ('xlsx',)
 
 def detect(stream):
     """Returns True if given stream is a readable excel file."""
+    if isinstance(stream, bytes):
+        # load_workbook expects a file-like object.
+        stream = BytesIO(stream)
     try:
-        openpyxl.reader.excel.load_workbook(stream)
+        openpyxl.reader.excel.load_workbook(stream, read_only=True)
         return True
     except openpyxl.shared.exc.InvalidFileException:
         pass
diff --git a/test_tablib.py b/test_tablib.py
index e4f1543..012f89d 100755
--- a/test_tablib.py
+++ b/test_tablib.py
@@ -13,7 +13,7 @@ from uuid import uuid4
 from MarkupPy import markup
 import tablib
 from tablib.compat import unicode, is_py3
-from tablib.core import Row
+from tablib.core import Row, detect_format
 from tablib.formats import _csv as csv_module
 
 
@@ -783,6 +783,16 @@ class TSVTests(BaseTestCase):
 
 
 class XLSXTests(BaseTestCase):
+    def test_xlsx_format_detect(self):
+        """Test the XLSX format detection."""
+        in_stream = self.founders.xlsx
+        self.assertEqual(detect_format(in_stream), 'xlsx')
+
+    def test_xls_format_detect(self):
+        """Test the XLS format detection."""
+        in_stream = self.founders.xls
+        self.assertEqual(detect_format(in_stream), 'xls')
+
     def test_xlsx_import_set(self):
         date_time = datetime.datetime(2019, 10, 4, 12, 30, 8)
         data.append(('string', 42, 21.55, date_time))