(arrow-rs) branch main updated: Fix Variant time microsecond JSON formatting (#10173)

[jeffreyvo]

This is an automated email from the ASF dual-hosted git repository.

Jefffrey pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/arrow-rs.git


The following commit(s) were added to refs/heads/main by this push:
     new 7c6209f823 Fix Variant time microsecond JSON formatting (#10173)
7c6209f823 is described below

commit 7c6209f823bcc0f7db9670f4cd513a2cd2dcea76
Author: Minh Vu <vuhoangmin...@gmail.com>
AuthorDate: Mon Jun 22 05:54:16 2026 +0200

    Fix Variant time microsecond JSON formatting (#10173)
    
    ### What changed
    
    This updates Variant `Time` JSON formatting to trim only trailing zeros
    from fractional microseconds.
    
    ### Why
    
    The previous formatter used `trim_matches('0')`, which removed leading
    zeros as well as trailing zeros. That could change values like `.010010`
    into `.1001` during JSON serialization.
    
    ### Validation
    
    - `cargo fmt --package parquet-variant-json`
    - `cargo test -p parquet-variant-json test_time_to_json`
---
 parquet-variant-json/src/to_json.rs | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/parquet-variant-json/src/to_json.rs 
b/parquet-variant-json/src/to_json.rs
index 707b1fe0a3..9e538877fb 100644
--- a/parquet-variant-json/src/to_json.rs
+++ b/parquet-variant-json/src/to_json.rs
@@ -362,7 +362,7 @@ fn format_time_ntz_str(time: &chrono::NaiveTime) -> String {
         0 => format!("{}.{}", base, 0),
         _ => {
             let micros_str = format!("{:06}", micros);
-            let micros_str_trimmed = micros_str.trim_matches('0');
+            let micros_str_trimmed = micros_str.trim_end_matches('0');
             format!("{}.{}", base, micros_str_trimmed)
         }
     }
@@ -509,6 +509,21 @@ mod tests {
         let json = variant.to_json_string()?;
         assert_eq!("\"03:25:45.12346\"", json);
 
+        let expected = [
+            (10, "00:00:00.00001"),
+            (10010, "00:00:00.01001"),
+            (100000, "00:00:00.1"),
+            (123450, "00:00:00.12345"),
+        ];
+
+        for (micros, expected_json) in expected {
+            let naive_time =
+                NaiveTime::from_num_seconds_from_midnight_opt(0, micros * 
1000).unwrap();
+            let variant = Variant::Time(naive_time);
+            let json = variant.to_json_string()?;
+            assert_eq!(format!("\"{expected_json}\""), json);
+        }
+
         let json_value = variant.to_json_value()?;
         assert!(matches!(json_value, Value::String(_)));
         Ok(())