URL.render_as_string doesn't always give an URL that is parsed same way about sqlalchemy

[CaselIT]

Hi,

I think this is expected behaviour. A string is interpreted as an url, so the ? delimits the query from the path.

[zzzeek]

it looks like a bug . they are creating the URL programattically. The name of the database is a?b=c. that should round trip.

That said, nobody would ever have a database name like that. so what's the XY problem here? (e.g. what do you actually need to do ?)

[AlexeyDmitriev]

@CaselIT Hi, I might have been confusing:
I understand that if I pass sqlite:///a?b=c then, b=c are parsed as query and it is expected

What in my view is not expected is the fact, that first_url_as_string contains this ? directly (instead of some kind of escaping, e.g urlencoded, etc), so that it would roundtrip well

[zzzeek]

this is the patch, this is for 2.1 only as URL adjustments are extremely high risk

diff --git a/lib/sqlalchemy/engine/url.py b/lib/sqlalchemy/engine/url.py
index 1eeb73a23..7565252c7 100644
--- a/lib/sqlalchemy/engine/url.py
+++ b/lib/sqlalchemy/engine/url.py
@@ -641,7 +641,7 @@ class URL(NamedTuple):
         if self.port is not None:
             s += ":" + str(self.port)
         if self.database is not None:
-            s += "/" + self.database
+            s += "/" + quote_plus(self.database)
         if self.query:
             keys = list(self.query)
             keys.sort()
@@ -888,11 +888,10 @@ def _parse_url(name: str) -> URL:
             query = None
         components["query"] = query
 
-        if components["username"] is not None:
-            components["username"] = unquote(components["username"])
+        for comp in "username", "password", "database":
+            if components[comp] is not None:
+                components[comp] = unquote(components[comp])
 
-        if components["password"] is not None:
-            components["password"] = unquote(components["password"])
 
         ipv4host = components.pop("ipv4host")
         ipv6host = components.pop("ipv6host")

[AlexeyDmitriev]

@zzzeek

I tried to understand whether I needed to escape my path when building an URL as a string (we don't have any strange character in the path to database but I wanted to fix it just in case). I've found that I can use URL class.
But while I was playing with it, I've noticed that behaviour is not what I expected

So, this behaviour doesn't bother me, I've already solved my problem, just decided to report what for me looks like a bug

[CaselIT]

I fear that the patch above will break existing use cases, since I'm not sure what all the various db driver would do in this case.

tried to create a db named "my?db=1" in pg and all kind of tools are failing to connect. Like I can't manage to connect using psql... Psycopg2 works though

[zzzeek]

this is less sensitive than "password". this breaks if someone had a database named "a%3Fb%3Dc" with URL escape symbols in it, that's basically it.

[CaselIT]

sure, probably not a big dial, but needs a breaking change node