(arrow) branch main updated: GH-45915: [JS] Ensure UnionBuilder yields chunks with correct length (#45916)

[domoritz]

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

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


The following commit(s) were added to refs/heads/main by this push:
     new 89fdbb9968 GH-45915: [JS] Ensure UnionBuilder yields chunks with 
correct length (#45916)
89fdbb9968 is described below

commit 89fdbb9968b7031be21a41a9874b3dc4a61cf953
Author: Paul Taylor <178183+trxcl...@users.noreply.github.com>
AuthorDate: Tue Mar 25 10:25:15 2025 -0700

    GH-45915: [JS] Ensure UnionBuilder yields chunks with correct length 
(#45916)
    
    ### Rationale for this change
    Fixes https://github.com/apache/arrow/issues/45915
    
    ### Are these changes tested?
    Yes
    
    ### Are there any user-facing changes?
    Yes
    
    * GitHub Issue: #45915
---
 js/src/builder/union.ts        | 2 ++
 js/test/unit/builders/utils.ts | 1 +
 2 files changed, 3 insertions(+)

diff --git a/js/src/builder/union.ts b/js/src/builder/union.ts
index 7bee460a77..6b6f4d476d 100644
--- a/js/src/builder/union.ts
+++ b/js/src/builder/union.ts
@@ -56,6 +56,7 @@ export abstract class UnionBuilder<T extends Union, TNull = 
any> extends Builder
         const childIndex = this.type.typeIdToChildIndex[childTypeId!];
         const child = this.children[childIndex];
         child?.set(index, value);
+        this.length = Math.max(index + 1, this.length);
     }
 
     public addChild(child: Builder, name = `${this.children.length}`) {
@@ -93,5 +94,6 @@ export class DenseUnionBuilder<T extends DenseUnion, TNull = 
any> extends UnionB
         const child = this.getChildAt(this.type.typeIdToChildIndex[id])!;
         const denseIndex = this._offsets.set(index, 
child.length).buffer[index];
         child?.set(denseIndex, value);
+        this.length = Math.max(index + 1, this.length);
     }
 }
diff --git a/js/test/unit/builders/utils.ts b/js/test/unit/builders/utils.ts
index 7cc0a075d8..1ea6a4e1f2 100644
--- a/js/test/unit/builders/utils.ts
+++ b/js/test/unit/builders/utils.ts
@@ -141,6 +141,7 @@ export function validateVector<T extends DataType>(vals: 
(T['TValue'] | null)[],
     let i = 0, x: T['TValue'] | null, y: T['TValue'] | null;
     const nulls = nullVals.reduce((m, x) => m.set(x, x), new Map());
     try {
+        expect(vec).toHaveLength(vals.length);
         for (x of vec) {
             if (nulls.has(y = vals[i])) {
                 expect(x).toBeNull();