Tilde encoding now encodes space as plus, closes #1701

Refs #1657

datasette/utils/__init__.py

@@ -1113,12 +1113,20 @@ _TILDE_ENCODING_SAFE = frozenset(
     # '.' and '~'
 )
 
+_space = ord(" ")
+
 
 class TildeEncoder(dict):
     # Keeps a cache internally, via __missing__
     def __missing__(self, b):
+        print("b is ", b)
         # Handle a cache miss, store encoded string in cache and return.
-        res = chr(b) if b in _TILDE_ENCODING_SAFE else "~{:02X}".format(b)
+        if b in _TILDE_ENCODING_SAFE:
+            res = chr(b)
+        elif b == _space:
+            res = "+"
+        else:
+            res = "~{:02X}".format(b)
         self[b] = res
         return res
 
@@ -1138,7 +1146,7 @@ def tilde_decode(s: str) -> str:
     # Avoid accidentally decoding a %2f style sequence
     temp = secrets.token_hex(16)
     s = s.replace("%", temp)
-    decoded = urllib.parse.unquote(s.replace("~", "%"))
+    decoded = urllib.parse.unquote_plus(s.replace("~", "%"))
     return decoded.replace(temp, "%")
 
 

docs/internals.rst

@@ -980,15 +980,17 @@ Datasette uses a custom encoding scheme in some places, called **tilde encoding*
 
 Tilde encoding uses the same algorithm as `URL percent-encoding <https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding>`__, but with the ``~`` tilde character used in place of ``%``.
 
-Any character other than ``ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789_-`` will be replaced by the numeric equivalent preceded by a tilde. For example:
+Any character other than ``ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz0123456789_-`` will be replaced by the numeric equivalent preceded by a tilde. For example:
 
 - ``/`` becomes ``~2F``
 - ``.`` becomes ``~2E``
 - ``%`` becomes ``~25``
 - ``~`` becomes ``~7E``
-- Space character becomes ``~20``
+- Space becomes ``+``
 - ``polls/2022.primary`` becomes ``polls~2F2022~2Eprimary``
 
+Note that the space character is a special case: it will be replaced with a ``+`` symbol.
+
 .. _internals_utils_tilde_encode:
 
 .. autofunction:: datasette.utils.tilde_encode

tests/test_html.py

@@ -28,7 +28,7 @@ def test_homepage(app_client_two_attached_databases):
     )
     # Should be two attached databases
     assert [
-        {"href": "/extra~20database", "text": "extra database"},
+        {"href": "/extra+database", "text": "extra database"},
         {"href": "/fixtures", "text": "fixtures"},
     ] == [{"href": a["href"], "text": a.text.strip()} for a in soup.select("h2 a")]
     # Database should show count text and attached tables
@@ -43,8 +43,8 @@ def test_homepage(app_client_two_attached_databases):
         {"href": a["href"], "text": a.text.strip()} for a in links_p.findAll("a")
     ]
     assert [
-        {"href": r"/extra~20database/searchable", "text": "searchable"},
-        {"href": r"/extra~20database/searchable_view", "text": "searchable_view"},
+        {"href": r"/extra+database/searchable", "text": "searchable"},
+        {"href": r"/extra+database/searchable_view", "text": "searchable_view"},
     ] == table_links
 
 

tests/test_utils.py

@@ -618,6 +618,7 @@ async def test_derive_named_parameters(sql, expected):
         ("-/db-/table.csv", "-~2Fdb-~2Ftable~2Ecsv"),
         (r"%~-/", "~25~7E-~2F"),
         ("~25~7E~2D~2F", "~7E25~7E7E~7E2D~7E2F"),
+        ("with space", "with+space"),
     ),
 )
 def test_tilde_encoding(original, expected):