feat: skip unsupported codecs/storage transformers with "must_understand": false (ZEP0009)

zarrs/src/array/codec/array_to_bytes/codec_chain.rs

@@ -134,7 +134,17 @@
         let mut array_to_bytes: Option<NamedArrayToBytesCodec> = None;
         let mut bytes_to_bytes: Vec<NamedBytesToBytesCodec> = vec![];
         for metadata in metadatas {
-            let codec = Codec::from_metadata(metadata)?;
+            let codec = match Codec::from_metadata(metadata) {
+                Ok(codec) => Ok(codec),
+                Err(err) => {
+                    if metadata.must_understand() {
+                        Err(err)
+                    } else {
+                        continue;
+                    }
+                }
+            }?;
+
             match codec {
                 Codec::ArrayToArray(codec) => {
                     array_to_array.push(NamedArrayToArrayCodec::new(

zarrs/src/array/storage_transformer/storage_transformer_chain.rs

@@ -37,7 +37,16 @@
     ) -> Result<Self, PluginCreateError> {
         let mut storage_transformers = Vec::with_capacity(metadatas.len());
         for metadata in metadatas {
-            let storage_transformer = try_create_storage_transformer(metadata, path)?;
+            let storage_transformer = match try_create_storage_transformer(metadata, path) {
+                Ok(storage_transformer) => Ok(storage_transformer),
+                Err(err) => {
+                    if metadata.must_understand() {
+                        Err(err)
+                    } else {
+                        continue;
+                    }
+                }
+            }?;
             storage_transformers.push(storage_transformer);
         }
         Ok(Self(storage_transformers))

zarrs_metadata/CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Add support for a `must_understand` field to `MetadataV3` (ZEP0009)
   - Extensions can now be parsed in more than just the additional fields of array/group metadata (e.g. codecs)
+  - Automatically skip unsupported codecs/storage transformers with `"must_understand": false`
 - Add `CodecMap` and `CodecName` for codec `nam` overriding and aliasing
 - Implement `From<T> for MetadataConfiguration` for all codec configuration enums
 - Implement `Copy` for `ZstdCompressionLevel`