Auto-link column values that look like URLs

Refs #153

datasette/app.py

@@ -25,6 +25,7 @@
     escape_sqlite_table_name,
     filters_should_redirect,
     get_all_foreign_keys,
+    is_url,
     InvalidSql,
     path_from_row_pks,
     path_with_added_args,
@@ -443,6 +444,10 @@ async def make_display_rows(self, database, database_hash, table, rows, display_
                     )
                 elif value is None:
                     display_value = jinja2.Markup(' ')
+                elif is_url(str(value).strip()):
+                    display_value = jinja2.Markup(
+                        '<a href="{url}">{url}</a>'.format(url=value.strip())
+                    )
                 else:
                     display_value = str(value)
                 cells.append({

datasette/utils.py

@@ -441,3 +441,18 @@ def filters_should_redirect(special_args):
             ('_filter_value_{}'.format(number), None),
         ])
     return redirect_params
+
+
+whitespace_re = re.compile(r'\s')
+
+
+def is_url(value):
+    "Must start with http:// or https:// and contain JUST a URL"
+    if not isinstance(value, str):
+        return False
+    if not value.startswith('http://') and not value.startswith('https://'):
+        return False
+    # Any whitespace at all is invalid
+    if whitespace_re.search(value):
+        return False
+    return True

tests/test_utils.py

@@ -151,3 +151,13 @@ def test_detect_fts():
     assert None is utils.detect_fts(conn, 'Dumb_Table')
     assert None is utils.detect_fts(conn, 'Test_View')
     assert 'Street_Tree_List_fts' == utils.detect_fts(conn, 'Street_Tree_List')
+
+
+@pytest.mark.parametrize('url,expected', [
+    ('http://www.google.com/', True),
+    ('https://example.com/', True),
+    ('www.google.com', False),
+    ('http://www.google.com/ is a search engine', False),
+])
+def test_is_url(url, expected):
+    assert expected == utils.is_url(url)