[wrangler] Fix d1 execute --json returning string "null" for SQL NULL values (#12808)

MaxwellCalkin · web-flow · commit 6ed249b77aa8 · 2026-03-09T16:43:43.000Z
diff --git a/.changeset/fix-d1-json-null-values.md b/.changeset/fix-d1-json-null-values.md
@@ -0,0 +1,7 @@
+---
+"wrangler": patch
+---
+
+Fix `wrangler d1 execute --json` returning `"null"` (string) instead of `null` (JSON null) for SQL NULL values
+
+When using `wrangler d1 execute --json` with local execution, SQL NULL values were incorrectly serialized as the string `"null"` instead of JSON `null`. This produced invalid JSON output that violated RFC 4627. The fix removes the explicit null-to-string conversion so NULL values are preserved as proper JSON null in the output.
diff --git a/packages/wrangler/src/__tests__/d1/execute.test.ts b/packages/wrangler/src/__tests__/d1/execute.test.ts
@@ -230,6 +230,23 @@ describe("execute", () => {
 		]);
 	});
 
+	it("should output JSON null for SQL NULL values with --json flag", async ({
+		expect,
+	}) => {
+		setIsTTY(false);
+		writeWranglerConfig({
+			d1_databases: [
+				{ binding: "DATABASE", database_name: "db", database_id: "xxxx" },
+			],
+		});
+
+		await runWrangler(
+			"d1 execute db --command 'SELECT 1 as id, null as name;' --json"
+		);
+		const parsed = JSON.parse(std.out);
+		expect(parsed[0].results[0].name).toBeNull();
+	});
+
 	describe("duration formatting", () => {
 		mockAccountId({ accountId: "some-account-id" });
 		mockApiToken();
diff --git a/packages/wrangler/src/d1/execute.ts b/packages/wrangler/src/d1/execute.ts
@@ -33,7 +33,7 @@ import type { D1Result } from "@cloudflare/workers-types/experimental";
 import type { ComplianceConfig, Config } from "@cloudflare/workers-utils";
 
 export type QueryResult = {
-	results: Record<string, string | number | boolean>[];
+	results: Record<string, string | number | boolean | null>[];
 	success: boolean;
 	meta?: {
 		duration?: number;
@@ -328,9 +328,6 @@ async function executeLocally({
 					if (Array.isArray(value)) {
 						value = `[${value.join(", ")}]`;
 					}
-					if (value === null) {
-						value = "null";
-					}
 					return [key, value];
 				})
 			)
