Add consolidated_metadata serialisation and deserialisation

Add `Node::consolidate_metadata()`

Add `Group::[set_]consolidated_metadata()`

zarrs/src/group.rs

@@ -30,6 +30,7 @@ use std::sync::Arc;
 
 use derive_more::Display;
 use thiserror::Error;
+use zarrs_metadata::v3::group::ConsolidatedMetadata;
 
 use crate::{
     config::{
@@ -150,6 +151,30 @@ impl<TStorage: ?Sized> Group<TStorage> {
             (GM::V2(metadata), V::V3) => GM::V3(group_metadata_v2_to_v3(&metadata)),
         }
     }
+
+    /// Get the consolidated metadata. Returns [`None`] if `consolidated_metadata` is absent.
+    ///
+    /// Consolidated metadata is not currently supported for Zarr V2 groups.
+    #[must_use]
+    pub fn consolidated_metadata(&self) -> Option<&ConsolidatedMetadata> {
+        if let GroupMetadata::V3(group_metadata) = &self.metadata {
+            group_metadata.consolidated_metadata.as_ref()
+        } else {
+            None
+        }
+    }
+
+    /// Set the consolidated metadata.
+    ///
+    /// Consolidated metadata is not currently supported for Zarr V2 groups, and this function is a no-op.
+    pub fn set_consolidated_metadata(
+        &mut self,
+        consolidated_metadata: Option<ConsolidatedMetadata>,
+    ) {
+        if let GroupMetadata::V3(group_metadata) = &mut self.metadata {
+            group_metadata.consolidated_metadata = consolidated_metadata;
+        }
+    }
 }
 
 impl<TStorage: ?Sized + ReadableStorageTraits> Group<TStorage> {

zarrs/src/node.rs

@@ -24,8 +24,9 @@ pub use key::{
 mod node_async;
 #[cfg(feature = "async")]
 pub use node_async::{async_get_child_nodes, async_node_exists, async_node_exists_listable};
+use zarrs_metadata::v3::group::ConsolidatedMetadataMetadata;
 
-use std::sync::Arc;
+use std::{collections::HashMap, sync::Arc};
 
 pub use crate::metadata::NodeMetadata;
 use thiserror::Error;
@@ -389,6 +390,31 @@ impl Node {
         update_tree(&mut string, &self.children, 1);
         string
     }
+
+    /// Consolidate metadata. Returns [`None`] for an array.
+    ///
+    /// [`ConsolidatedMetadataMetadata`] can be converted into [`ConsolidatedMetadata`](crate::metadata::v3::group::ConsolidatedMetadata) in [`GroupMetadataV3`](crate::metadata::v3::group::GroupMetadataV3).
+    #[must_use]
+    #[allow(clippy::items_after_statements)]
+    pub fn consolidate_metadata(&self) -> Option<ConsolidatedMetadataMetadata> {
+        if let NodeMetadata::Array(_) = self.metadata {
+            // Arrays cannot have consolidated metadata
+            return None;
+        }
+
+        fn update_consolidated_metadata(
+            consolidated_metadata: &mut ConsolidatedMetadataMetadata,
+            children: &[Node],
+        ) {
+            for child in children {
+                consolidated_metadata.insert(child.path().to_string(), child.metadata.clone());
+                update_consolidated_metadata(consolidated_metadata, &child.children);
+            }
+        }
+        let mut consolidated_metadata = HashMap::default();
+        update_consolidated_metadata(&mut consolidated_metadata, &self.children);
+        Some(consolidated_metadata)
+    }
 }
 
 #[cfg(test)]

zarrs/tests/hierarchy.rs

@@ -1,7 +1,11 @@
+#![cfg(feature = "filesystem")]
+
 use std::sync::Arc;
 
-use zarrs::node::Node;
-use zarrs_filesystem::FilesystemStore;
+use zarrs::{
+    filesystem::FilesystemStore, group::Group, metadata::v3::group::ConsolidatedMetadata,
+    node::Node,
+};
 
 #[test]
 fn hierarchy_tree() {
@@ -23,3 +27,28 @@ fn hierarchy_tree() {
 "
     );
 }
+
+#[test]
+fn consolidated_metadata() {
+    let store = Arc::new(
+        FilesystemStore::new("./tests/data/hierarchy.zarr")
+            .unwrap()
+            .sorted(),
+    );
+    let node = Node::open(&store, "/").unwrap();
+    let consolidated_metadata = node.consolidate_metadata().unwrap();
+
+    for node_path in ["/a/baz", "/a/foo", "/b"] {
+        let consolidated = consolidated_metadata.get(node_path).unwrap();
+        let actual = Node::open(&store, node_path).unwrap();
+        assert_eq!(consolidated, actual.metadata());
+    }
+
+    let mut group = Group::open(store, "/").unwrap();
+    assert!(group.consolidated_metadata().is_none());
+    group.set_consolidated_metadata(Some(ConsolidatedMetadata {
+        metadata: consolidated_metadata,
+        ..Default::default()
+    }));
+    assert!(group.consolidated_metadata().is_some());
+}

zarrs_metadata/src/v3/group.rs

@@ -1,6 +1,10 @@
+use std::collections::HashMap;
+
 use derive_more::Display;
 use serde::{Deserialize, Serialize};
 
+use crate::NodeMetadata;
+
 use super::AdditionalFields;
 
 /// Zarr group metadata (storage specification v3).
@@ -18,7 +22,7 @@ use super::AdditionalFields;
 ///     }
 /// }
 #[non_exhaustive]
-#[derive(Serialize, Deserialize, Clone, Eq, PartialEq, Debug, Display)]
+#[derive(Serialize, Deserialize, Clone, Debug, Display)]
 #[display("{}", serde_json::to_string(self).unwrap_or_default())]
 pub struct GroupMetadataV3 {
     /// An integer defining the version of the storage specification to which the group adheres. Must be `3`.
@@ -28,11 +32,24 @@ pub struct GroupMetadataV3 {
     /// Optional user metadata.
     #[serde(default, skip_serializing_if = "serde_json::Map::is_empty")]
     pub attributes: serde_json::Map<String, serde_json::Value>,
+    /// Consolidated metadata.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub consolidated_metadata: Option<ConsolidatedMetadata>,
     /// Additional fields.
     #[serde(flatten)]
     pub additional_fields: AdditionalFields,
 }
 
+impl std::cmp::PartialEq for GroupMetadataV3 {
+    fn eq(&self, other: &Self) -> bool {
+        self.attributes == other.attributes
+            // && self.consolidated_metadata == other.consolidated_metadata
+            && self.additional_fields == other.additional_fields
+    }
+}
+
+impl Eq for GroupMetadataV3 {}
+
 impl Default for GroupMetadataV3 {
     fn default() -> Self {
         Self::new(serde_json::Map::new(), AdditionalFields::default())
@@ -51,6 +68,92 @@ impl GroupMetadataV3 {
             node_type: monostate::MustBe!("group"),
             attributes,
             additional_fields,
+            consolidated_metadata: None,
         }
     }
 }
+
+/// Consolidated metadata of a Zarr hierarchy.
+#[derive(Serialize, Deserialize, Clone, PartialEq, Debug, Display)]
+#[display("{}", serde_json::to_string(self).unwrap_or_default())]
+pub struct ConsolidatedMetadata {
+    /// A mapping from node path to Group or Array [`NodeMetadata`] object.
+    pub metadata: ConsolidatedMetadataMetadata,
+    /// The kind of the consolidated metadata. Must be `'inline'`. Reserved for future use.
+    pub kind: ConsolidatedMetadataKind,
+    /// The boolean literal `false`. Indicates that the field is not required to load the Zarr hierarchy.
+    pub must_understand: monostate::MustBe!(false),
+}
+
+/// The `metadata` field of `consolidated_metadata` in [`GroupMetadataV3`].
+pub type ConsolidatedMetadataMetadata = HashMap<String, NodeMetadata>;
+
+impl Default for ConsolidatedMetadata {
+    fn default() -> Self {
+        Self {
+            metadata: HashMap::default(),
+            kind: ConsolidatedMetadataKind::Inline,
+            must_understand: monostate::MustBe!(false),
+        }
+    }
+}
+
+/// The "kind" of consolidated metadata.
+#[non_exhaustive]
+#[derive(Serialize, Deserialize, Clone, Eq, PartialEq, Debug, Display)]
+pub enum ConsolidatedMetadataKind {
+    /// Indicates that consolidated metadata is stored inline in the root `zarr.json` object.
+    #[serde(rename = "inline")]
+    Inline,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn group_metadata_consolidated() {
+        let group_metadata = serde_json::from_str::<GroupMetadataV3>(
+            r#"{
+            "zarr_format": 3,
+            "node_type": "group",
+            "attributes": {
+                "spam": "ham",
+                "eggs": 42
+            },
+            "consolidated_metadata": {
+                "metadata": {
+                    "/subgroup": {
+                        "zarr_format": 3,
+                        "node_type": "group",
+                        "attributes": {
+                            "consolidated": "attributes"
+                        }
+                    }
+                },
+                "kind": "inline",
+                "must_understand": false
+            }
+        }"#,
+        )
+        .unwrap();
+        assert_eq!(
+            group_metadata
+                .consolidated_metadata
+                .unwrap()
+                .metadata
+                .get("/subgroup")
+                .unwrap(),
+            &serde_json::from_str::<NodeMetadata>(
+                r#"{
+                    "zarr_format": 3,
+                    "node_type": "group",
+                    "attributes": {
+                        "consolidated": "attributes"
+                    }
+                }"#
+            )
+            .unwrap()
+        );
+    }
+}