[Rust]: Json reader for nested dictionary arrays returns empty array instead of array of nulls

[asfimport]

 

// schema: id: Utf8, attr: List<Dictionary<Utf8>>
        let input = json!([
            {"id": "a"},
            {"id": "b"},
            {"id": "c"},
            {"id": "d"},
            {"id": "e"},
        ]);

// Results in ArrowError("InvalidArgumentError(\"all columns in a record batch must have the same length\")")

Probably related to list_array_string_array_builder around line 688:

if let Some(value) = row.get(col_name) { 
...
}
// no else

 

Expected: The resulting array should have a length equal to the number of rows, all nested lists should be marked as null.

Reporter: Jörn Horstmann / @jhorstmann

_{Note: This issue was originally created as ARROW-11648. Please see the migration documentation for further details.}

[asfimport]

Andrew Lamb / @alamb:
Migrated to github: apache/arrow-rs#188