From cac352926a401fed840bab53ec2c1af4cf4b3996 Mon Sep 17 00:00:00 2001
From: Osama Ansar <osama.ansar.pk@gmail.com>
Date: Tue, 13 Oct 2026 01:12:18 +0500
Subject: [PATCH] Fixed parsing of empty sparsevec in SparseVector

An all-zero sparsevec is returned by Postgres as {}/n. Splitting the empty
body on ',' gave [''], so the constructor pushed parseInt('') - 1 and
parseFloat(undefined), leaving NaN in indices and values.
---
 src/sparse-vector.js        | 13 ++++++++-----
 tests/sparse-vector.test.js | 10 ++++++++++
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/sparse-vector.js b/src/sparse-vector.js
index fac13e5..5e8d73d 100644
--- a/src/sparse-vector.js
+++ b/src/sparse-vector.js
@@ -72,11 +72,14 @@ export class SparseVector {
 
     this.dimensions = parseInt(parts[1]);
 
-    const elements = parts[0].slice(1, -1).split(',');
-    for (const element of elements) {
-      const ep = element.split(':', 2);
-      this.indices.push(parseInt(ep[0]) - 1);
-      this.values.push(parseFloat(ep[1]));
+    // all-zero vectors are {}/n
+    const body = parts[0].slice(1, -1);
+    if (body !== '') {
+      for (const element of body.split(',')) {
+        const ep = element.split(':', 2);
+        this.indices.push(parseInt(ep[0]) - 1);
+        this.values.push(parseFloat(ep[1]));
+      }
     }
   }
 
diff --git a/tests/sparse-vector.test.js b/tests/sparse-vector.test.js
index 9923ac8..d448fa4 100644
--- a/tests/sparse-vector.test.js
+++ b/tests/sparse-vector.test.js
@@ -10,6 +10,16 @@ test('fromSql', () => {
   assert.deepEqual(vec.values, [1, 2, 3]);
 });
 
+test('fromSqlEmpty', () => {
+  const vec = new SparseVector('{}/3');
+  assert.deepEqual(vec.toArray(), [0, 0, 0]);
+  assert.equal(vec.dimensions, 3);
+  assert.deepEqual(vec.indices, []);
+  assert.deepEqual(vec.values, []);
+  assert.equal(vec.toPostgres(), '{}/3');
+  assert.deepEqual(Object.keys(vec.toArray()), ['0', '1', '2']);
+});
+
 test('fromDense', () => {
   const vec = new SparseVector([1, 0, 2, 0, 3, 0]);
   assert.equal(vec.toPostgres(), '{1:1,3:2,5:3}/6');