feat: Support serializing serde_bytes::Bytes as hex string literals (#250)

Author: DCjanus

src/sql/escape.rs

@@ -29,6 +29,16 @@ pub(crate) fn escape(src: &str, dst: &mut impl fmt::Write) -> fmt::Result {
     dst.write_str(rest)
 }
 
+// See https://clickhouse.com/docs/en/sql-reference/syntax#string
+pub(crate) fn hex_bytes(s: &[u8], dst: &mut impl fmt::Write) -> fmt::Result {
+    dst.write_char('X')?;
+    dst.write_char('\'')?;
+    for &byte in s {
+        write!(dst, "{byte:02X}")?;
+    }
+    dst.write_char('\'')
+}
+
 #[test]
 fn it_escapes_string() {
     let mut actual = String::new();

src/sql/ser.rs

@@ -85,11 +85,16 @@ impl<'a, W: Write> Serializer for SqlSerializer<'a, W> {
 
     unsupported!(
         serialize_map(Option<usize>) -> Result<Impossible>,
-        serialize_bytes(&[u8]),
         serialize_unit,
         serialize_unit_struct(&'static str),
     );
 
+    #[inline]
+    fn serialize_bytes(self, value: &[u8]) -> Result {
+        escape::hex_bytes(value, self.writer)?;
+        Ok(())
+    }
+
     forward_to_display!(
         serialize_i8(i8),
         serialize_i16(i16),
@@ -458,6 +463,33 @@ mod tests {
         out
     }
 
+    #[test]
+    fn it_writes_bytes() {
+        use serde_bytes::ByteArray;
+        use serde_bytes::ByteBuf;
+        use serde_bytes::Bytes;
+
+        assert_eq!(check(Bytes::new(b"hello")), "X'68656C6C6F'");
+        assert_eq!(check(Bytes::new(b"")), "X''");
+        assert_eq!(check(Bytes::new(b"a\xffb")), "X'61FF62'");
+        assert_eq!(check(Bytes::new(b"a'b")), "X'612762'");
+
+        assert_eq!(check(ByteArray::new(*b"hello")), "X'68656C6C6F'");
+        assert_eq!(check(ByteArray::new(*b"")), "X''");
+        assert_eq!(check(ByteArray::new(*b"a\xffb")), "X'61FF62'");
+        assert_eq!(check(ByteArray::new(*b"a'b")), "X'612762'");
+
+        assert_eq!(check(ByteBuf::from(b"hello")), "X'68656C6C6F'");
+        assert_eq!(check(ByteBuf::from(b"")), "X''");
+        assert_eq!(check(ByteBuf::from(b"a\xffb")), "X'61FF62'");
+        assert_eq!(check(ByteBuf::from(b"a'b")), "X'612762'");
+
+        assert_eq!(check(b"hello"), "(104,101,108,108,111)");
+        assert_eq!(check(b""), "()");
+        assert_eq!(check(b"a\xffb"), "(97,255,98)");
+        assert_eq!(check(b"a'b"), "(97,39,98)");
+    }
+
     #[test]
     fn it_writes_numeric_primitives() {
         assert_eq!(check(42), "42");