Minor fixes to ObjectList (#1398)

* fix: ObjectList handle missing apiVersion and kind during deserialization

The `serde` crate has a bug that prevents the proper deserialization of
attributes that are using the `flatten` and `default` directives.
See [1] and [2].

This bug affects the freshly introduced `ObjectList.types` attribute.
It's not possible to deserialize an `ObjectList` that is missing the
`apiVersion` and/or the `kind` values.

This commit introduces a custom deserializer for the `types` attribute
of `ObjectList`.

On top of handling the deserialization case, the custom deserializer
provides better default values compared to the ones of the stock
`TypeMeta`.
The `TypeMeta` struct has empty strings as default values. However, in the
context of `ObjectList`, proper default values should be `v1` and `List`
instead.

[1] serde-rs/serde#1626
[2] serde-rs/serde#1879

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

* ObjectList: derive the `Clone` trait

Ensure `ObjectList` derive the `Clone` trait.

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

* chore: fix rustfmt warning

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

---------

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

kube-core/src/object.rs

@@ -16,13 +16,13 @@ use std::borrow::Cow;
 /// and is generally produced from list/watch/delete collection queries on an [`Resource`](super::Resource).
 ///
 /// This is almost equivalent to [`k8s_openapi::List<T>`](k8s_openapi::List), but iterable.
-#[derive(Serialize, Deserialize, Debug)]
+#[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct ObjectList<T>
 where
     T: Clone,
 {
     /// The type fields, always present
-    #[serde(flatten, default)]
+    #[serde(flatten, deserialize_with = "deserialize_v1_list_as_default")]
     pub types: TypeMeta,
 
     /// ListMeta - only really used for its `resourceVersion`
@@ -38,6 +38,17 @@ where
     pub items: Vec<T>,
 }
 
+fn deserialize_v1_list_as_default<'de, D>(deserializer: D) -> Result<TypeMeta, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let meta = Option::<TypeMeta>::deserialize(deserializer)?;
+    Ok(meta.unwrap_or(TypeMeta {
+        api_version: "v1".to_owned(),
+        kind: "List".to_owned(),
+    }))
+}
+
 fn deserialize_null_as_default<'de, D, T>(deserializer: D) -> Result<T, D::Error>
 where
     T: Default + Deserialize<'de>,
@@ -394,4 +405,24 @@ mod test {
         assert!(mypod.status.is_none());
         assert!(mypod.spec.is_none());
     }
+
+    #[test]
+    fn k8s_object_list_default_types() {
+        use k8s_openapi::api::core::v1::Pod;
+
+        let raw_value = serde_json::json!({
+            "metadata": {
+                "resourceVersion": ""
+            },
+            "items": []
+        });
+        let pod_list: ObjectList<Pod> = serde_json::from_value(raw_value).unwrap();
+        assert_eq!(
+            TypeMeta {
+                api_version: "v1".to_owned(),
+                kind: "List".to_owned(),
+            },
+            pod_list.types,
+        );
+    }
 }