Fix property parsing when a property contains a struct (#210)

Properties are parsed lazily by deserializing the data into an `IgnoredAny`
and then returning the bytes that have been read.

We do parse structs as an enum in order to emit the struct tag as enum tag.
The `IgnoredAny` then deserializes a newtype enum variant, expecting a single item.
The `VariantAccess` impl for the packstream deserializer would then only emit the next field in the struct, introducing the bug.
The fix is to emit all fields when the list of items is from a struct and we are parsing properties.

Author: knutwalker

lib/src/bolt/structs/node.rs

@@ -188,7 +188,10 @@ mod tests {
     use serde_test::{assert_de_tokens, Token};
     use test_case::{test_case, test_matrix};
 
-    use crate::packstream::{bolt, from_bytes_ref, BoltBytesBuilder, Data};
+    use crate::{
+        bolt::LegacyDateTime,
+        packstream::{bolt, from_bytes_ref, BoltBytesBuilder, Data},
+    };
 
     use super::*;
 
@@ -335,4 +338,33 @@ mod tests {
             .tiny_string("Alice")
             .build()
     }
+
+    fn deserialize_properties_with_structs() {
+        let mut data = Data::new(
+            bolt()
+                .structure(3, 0x4E)
+                .tiny_int(42)
+                .tiny_list(1)
+                .tiny_string("Label")
+                .tiny_map(1)
+                .tiny_string("p")
+                .structure(3, b'F')
+                .int32(42)
+                .tiny_int(0)
+                .tiny_int(0)
+                .build(),
+        );
+        let mut node: NodeRef = from_bytes_ref(&mut data).unwrap();
+
+        assert_eq!(node.id(), 42);
+        assert_eq!(node.labels(), &["Label"]);
+        assert_eq!(node.element_id(), None);
+
+        assert_eq!(node.keys(), &["p"]);
+
+        let p = node.get::<LegacyDateTime>("p").unwrap().unwrap();
+        assert_eq!(p.seconds_since_epoch(), 42);
+        assert_eq!(p.nanoseconds(), 0);
+        assert_eq!(p.timezone_offset_seconds(), 0);
+    }
 }

lib/src/packstream/de.rs

@@ -1,10 +1,10 @@
-use std::{fmt, marker::PhantomData};
+use std::{any::type_name, fmt, marker::PhantomData};
 
 use bytes::{Buf, Bytes};
 use serde::{
     de::{
-        self, value::SeqDeserializer, DeserializeSeed, EnumAccess, IntoDeserializer as _,
-        MapAccess, SeqAccess, VariantAccess, Visitor,
+        self, value::SeqDeserializer, DeserializeSeed, EnumAccess, IgnoredAny,
+        IntoDeserializer as _, MapAccess, SeqAccess, VariantAccess, Visitor,
     },
     forward_to_deserialize_any,
 };
@@ -207,8 +207,10 @@ impl<'de> Deserializer<'de> {
         let start = full_bytes.as_ptr();
         let end = self.bytes.as_ptr();
 
+        // SAFETY: both pointers are from the same allocation and end is >= start
         let len = unsafe { end.offset_from(start) };
         full_bytes.truncate(len.unsigned_abs());
+
         Ok(full_bytes)
     }
 
@@ -358,20 +360,25 @@ impl<'a> ItemsParser<'a> {
         self.excess = excess;
         self
     }
+
+    fn drain(&mut self) -> Result<(), Error> {
+        let bytes = self.bytes.get();
+        for _ in 0..(self.len + self.excess) {
+            Deserializer { bytes }.skip_next_item()?;
+        }
+        Ok(())
+    }
 }
 
-impl<'a, 'de> SeqAccess<'de> for ItemsParser<'a> {
+impl<'de> SeqAccess<'de> for ItemsParser<'_> {
     type Error = Error;
 
     fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
     where
         T: DeserializeSeed<'de>,
     {
         if self.len == 0 {
-            let bytes = self.bytes.get();
-            for _ in 0..self.excess {
-                Deserializer { bytes }.skip_next_item()?;
-            }
+            self.drain()?;
             return Ok(None);
         }
         self.len -= 1;
@@ -388,7 +395,7 @@ impl<'a, 'de> SeqAccess<'de> for ItemsParser<'a> {
     }
 }
 
-impl<'a, 'de> MapAccess<'de> for ItemsParser<'a> {
+impl<'de> MapAccess<'de> for ItemsParser<'_> {
     type Error = Error;
 
     fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Self::Error>
@@ -420,7 +427,7 @@ impl<'a, 'de> MapAccess<'de> for ItemsParser<'a> {
     }
 }
 
-impl<'a, 'de> VariantAccess<'de> for ItemsParser<'a> {
+impl<'de> VariantAccess<'de> for ItemsParser<'_> {
     type Error = Error;
 
     fn unit_variant(mut self) -> Result<(), Self::Error> {
@@ -431,6 +438,11 @@ impl<'a, 'de> VariantAccess<'de> for ItemsParser<'a> {
     where
         T: DeserializeSeed<'de>,
     {
+        if type_name::<T>() == type_name::<PhantomData<IgnoredAny>>() {
+            self.drain()?;
+            return seed.deserialize(().into_deserializer());
+        }
+
         self.next_value_seed(seed)
     }
 
@@ -498,14 +510,14 @@ struct SharedBytes<'a> {
 }
 
 #[cfg(all(test, debug_assertions))]
-impl<'a> fmt::Debug for SharedBytes<'a> {
+impl fmt::Debug for SharedBytes<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         crate::packstream::Dbg(unsafe { &*self.bytes }).fmt(f)
     }
 }
 
 #[cfg(not(all(test, debug_assertions)))]
-impl<'a> fmt::Debug for SharedBytes<'a> {
+impl fmt::Debug for SharedBytes<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("SharedBytes").finish_non_exhaustive()
     }

lib/tests/node_property_parsing.rs

@@ -0,0 +1,23 @@
+use chrono::{DateTime, FixedOffset};
+use neo4rs::{query, Node};
+
+mod container;
+
+#[tokio::test]
+async fn node_property_parsing() {
+    let neo4j = container::Neo4jContainer::new().await;
+    let graph = neo4j.graph();
+
+    graph
+        .run(query("CREATE (:A {p1:DATETIME('2024-12-31T08:10:35')})"))
+        .await
+        .unwrap();
+
+    let mut result = graph.execute(query("MATCH (p:A) RETURN p")).await.unwrap();
+
+    while let Ok(Some(row)) = result.next().await {
+        let node: Node = row.get("p").unwrap();
+        let p1 = node.get::<DateTime<FixedOffset>>("p1").unwrap();
+        assert_eq!(p1.timestamp(), 1735632635);
+    }
+}