RUST-1819 Fix list_collections on Atlas for clustered collections (#1077)

---------

Co-authored-by: Jesse Hallett <[email protected]>

Author: isabelatkinson

src/db/options.rs

@@ -104,7 +104,8 @@ pub struct CreateCollectionOptions {
     /// Options for supporting change stream pre- and post-images.
     pub change_stream_pre_and_post_images: Option<ChangeStreamPreAndPostImages>,
 
-    /// Options for clustered collections.
+    /// Options for clustered collections. This option is only available on server versions 5.3+.
+    #[serde(default, deserialize_with = "ClusteredIndex::deserialize_self_or_true")]
     pub clustered_index: Option<ClusteredIndex>,
 
     /// Tags the query with an arbitrary [`Bson`] value to help trace the operation through the
@@ -176,6 +177,35 @@ impl Default for ClusteredIndex {
     }
 }
 
+impl ClusteredIndex {
+    /// When creating a time-series collection on MongoDB Atlas the `clusteredIndex` field of the
+    /// collection options is given as `true` instead of as an object that deserializes to
+    /// `ClusteredIndex`. This custom deserializer handles that case by using the default value for
+    /// `ClusteredIndex`.
+    fn deserialize_self_or_true<'de, D>(deserializer: D) -> Result<Option<ClusteredIndex>, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        #[derive(Debug, Deserialize)]
+        #[serde(untagged)]
+        enum ValueUnion {
+            Bool(bool),
+            ClusteredIndex(ClusteredIndex),
+        }
+
+        let value_option: Option<ValueUnion> = Deserialize::deserialize(deserializer)?;
+        value_option
+            .map(|value| match value {
+                ValueUnion::Bool(true) => Ok(ClusteredIndex::default()),
+                ValueUnion::Bool(false) => Err(serde::de::Error::custom(
+                    "if clusteredIndex is a boolean it must be `true`",
+                )),
+                ValueUnion::ClusteredIndex(value) => Ok(value),
+            })
+            .transpose()
+    }
+}
+
 /// Specifies default configuration for indexes created on a collection, including the _id index.
 #[derive(Clone, Debug, TypedBuilder, PartialEq, Serialize, Deserialize)]
 #[builder(field_defaults(default, setter(into)))]

src/test/db.rs

@@ -7,6 +7,7 @@ use crate::{
     bson::{doc, Document},
     error::Result,
     options::{
+        ClusteredIndex,
         Collation,
         CreateCollectionOptions,
         IndexOptionDefaults,
@@ -338,3 +339,42 @@ async fn index_option_defaults_test(defaults: Option<IndexOptionDefaults>, name:
     };
     assert_eq!(event_defaults, defaults);
 }
+
+#[test]
+fn deserialize_clustered_index_option_from_bool() {
+    let options_doc = doc! { "clusteredIndex": true };
+    let options: CreateCollectionOptions = bson::from_document(options_doc).unwrap();
+    let clustered_index = options
+        .clustered_index
+        .expect("deserialized options should include clustered_index");
+    assert_eq!(clustered_index, ClusteredIndex::default());
+}
+
+#[tokio::test]
+async fn clustered_index_list_collections() {
+    let client = TestClient::new().await;
+    let database = client.database("db");
+
+    if client.server_version_lt(5, 3) {
+        return;
+    }
+
+    database
+        .create_collection("clustered_index_collection")
+        .clustered_index(ClusteredIndex::default())
+        .await
+        .unwrap();
+
+    let collections = database
+        .list_collections()
+        .await
+        .unwrap()
+        .try_collect::<Vec<_>>()
+        .await
+        .unwrap();
+    let clustered_index_collection = collections
+        .iter()
+        .find(|specification| specification.name == "clustered_index_collection")
+        .unwrap();
+    assert!(clustered_index_collection.options.clustered_index.is_some());
+}