From 366d8de3f3983e97bc78dc5fd7125050ed1bfd47 Mon Sep 17 00:00:00 2001
From: sunlishuo <sunlishuo38@gmail.com>
Date: Sun, 4 Oct 2026 21:05:46 +0800
Subject: [PATCH] fix(csv-stringify): quote empty strings returned by casts

---
 packages/csv-stringify/lib/api/index.js       |  6 ++--
 .../csv-stringify/test/option.quoted_match.ts | 25 ++++++++++++++
 .../test/option.quoted_string.ts              | 33 +++++++++++++++++++
 3 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/packages/csv-stringify/lib/api/index.js b/packages/csv-stringify/lib/api/index.js
index 1fb77be2b..9c78ea91b 100644
--- a/packages/csv-stringify/lib/api/index.js
+++ b/packages/csv-stringify/lib/api/index.js
@@ -194,12 +194,14 @@ const stringifier = function (options, state, info) {
           quote_record_delimiter,
           escape_formulas,
         } = options;
-        if ("" === value && "" === field) {
+        if ("" === value) {
           const quotedMatch = matches_quoted_match(value, quoted_match);
           const shouldQuote =
             quotedMatch ||
             true === quoted_empty ||
-            (true === quoted_string && false !== quoted_empty);
+            (true === quoted_string &&
+              typeof field === "string" &&
+              false !== quoted_empty);
           if (shouldQuote === true) {
             value = quote + value + quote;
           }
diff --git a/packages/csv-stringify/test/option.quoted_match.ts b/packages/csv-stringify/test/option.quoted_match.ts
index 3770d1a3a..d9032923a 100644
--- a/packages/csv-stringify/test/option.quoted_match.ts
+++ b/packages/csv-stringify/test/option.quoted_match.ts
@@ -1,8 +1,33 @@
 import "should";
 import should from "should";
 import { stringify } from "../lib/index.js";
+import { stringify as stringifySync } from "../lib/sync.js";
 
 describe("Option `quoted_match`", function () {
+  it("matches an empty string returned by a string cast", function (next) {
+    stringify(
+      [[" ", "", null, undefined, "text"]],
+      { quoted_match: /^$/, cast: { string: (value) => value.trim() } },
+      (err, data) => {
+        if (err) return next(err);
+        data.should.eql('"","",,,text\n');
+        next();
+      },
+    );
+  });
+
+  it("matches empty cast values in the sync API and local options", function () {
+    const data = stringifySync([[" ", 0, {}, null, undefined]], {
+      quoted_match: /^$/,
+      cast: {
+        string: (value) => value.trim(),
+        number: () => "",
+        object: () => ({ value: "", quoted_match: "" }),
+      },
+    });
+    data.should.eql('"","","",,\n');
+  });
+
   it("default to `null`", function (next) {
     const stringifier = stringify([["abc", "def"]], () => {
       should(stringifier.options.quoted_match).be.null();
diff --git a/packages/csv-stringify/test/option.quoted_string.ts b/packages/csv-stringify/test/option.quoted_string.ts
index f3ee7ca75..c653befc8 100644
--- a/packages/csv-stringify/test/option.quoted_string.ts
+++ b/packages/csv-stringify/test/option.quoted_string.ts
@@ -1,7 +1,40 @@
 import "should";
 import { stringify } from "../lib/index.js";
+import { stringify as stringifySync } from "../lib/sync.js";
 
 describe("Option `quoted_string`", function () {
+  it("quotes a string cast to an empty string", function (next) {
+    stringify(
+      [[" ", "", null, undefined, "text"]],
+      { quoted_string: true, cast: { string: (value) => value.trim() } },
+      (err, data) => {
+        if (err) return next(err);
+        data.should.eql('"","",,,"text"\n');
+        next();
+      },
+    );
+  });
+
+  it("only quotes string fields when casts return empty strings", function () {
+    const data = stringifySync([[" ", "", 0, false, null, undefined]], {
+      quoted_string: true,
+      cast: {
+        string: (value) => value.trim(),
+        number: () => "",
+      },
+    });
+    data.should.eql('"","",,,,\n');
+  });
+
+  it("respects quoted_empty when strings are cast to empty strings", function () {
+    const data = stringifySync([[" ", ""]], {
+      quoted_string: true,
+      quoted_empty: false,
+      cast: { string: (value) => value.trim() },
+    });
+    data.should.eql(",\n");
+  });
+
   it("quotes string fields", function (next) {
     stringify(
       [[undefined, null, "", " ", "x", 0, false]],