fix(metadata): interpret 0 fill value as "0" for Zarr V2 arrays

This was the default in zarr-python 2.x.x.
LDeakin · Feb 7, 2025 · 4464d2a · 4464d2a
1 parent d24d316
commit 4464d2a
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/zarrs_metadata/CHANGELOG.md b/zarrs_metadata/CHANGELOG.md
@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- Interpret a `0` fill value as `"0"` for Zarr V2 string arrays (for `zarr-python` 2.x.x compatibility)
+
 ## [0.3.3] - 2025-02-06
 
 ### Fixed

diff --git a/zarrs_metadata/src/v2_to_v3.rs b/zarrs_metadata/src/v2_to_v3.rs
@@ -257,9 +257,10 @@ pub fn array_metadata_v2_to_v3(
             }
         }
     } else if data_type.name() == "string" {
-        // Add a special case for `zarr-python` string data with a 0 fill value -> empty string
+        // Add a special case for string data with a 0 fill value -> "0"
+        // This was the default in zarr-python 2.x.x.
         if let Some(0) = fill_value.try_as_uint::<u64>() {
-            fill_value = FillValueMetadataV3::String(String::new());
+            fill_value = FillValueMetadataV3::String("0".to_string());
         }
     }