wjones127 opened a new issue, #45862: URL: https://github.com/apache/arrow/issues/45862
### Describe the bug, including details regarding any error messages, version, and platform. `vectorFromArray` can produce an invalid FixedSizeList array, where the values length doesn't match the `list_size * length`. This makes other implementations error when they receive an IPC batch from JS. This only seems to happen when the null is at the end. If it's at the beginning, it works fine. ```js let arrow = require("apache-arrow"); let badArray = arrow.vectorFromArray( [[1, 2, 3], null], new arrow.FixedSizeList(3, new arrow.Field("item", new arrow.Float32())), ); badArray.getChildAt(0) ``` ``` Vector [FloatVector<Float>] { isValid: [Function (anonymous)], get: [Function (anonymous)], set: [Function (anonymous)], indexOf: [Function (anonymous)], _offsets: [ 0, 3 ], data: [ Data { type: [Float32 [Float]], children: [], dictionary: undefined, offset: 0, length: 3, _nullCount: 0, stride: 1, values: [Float32Array], nullBitmap: Uint8Array(0) [] } ], type: Float32 [Float] { typeId: 3, precision: 1 }, stride: 1, numChildren: 0, length: 3 // <-- This is incorrect! } ``` ```js let goodArray = arrow.vectorFromArray( [null, [1, 2, 3]], new arrow.FixedSizeList(3, new arrow.Field("item", new arrow.Float32())), ); goodArray.getChildAt(0) // null ``` ``` Vector [FloatVector<Float>] { isValid: [Function (anonymous)], get: [Function (anonymous)], set: [Function (anonymous)], indexOf: [Function (anonymous)], _offsets: [ 0, 6 ], data: [ Data { type: [Float32 [Float]], children: [], dictionary: undefined, offset: 0, length: 6, _nullCount: 3, stride: 1, values: [Float32Array], nullBitmap: [Uint8Array] } ], type: Float32 [Float] { typeId: 3, precision: 1 }, stride: 1, numChildren: 0, length: 6 // Correct :) } ``` We caught this when reading via IPC into arrow-rs. ### Component(s) JavaScript -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@arrow.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org