Fixed bigint handling for Zod 4 and Valibot.

Author: ciscoheat

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - SuperDebug rune version is back, can now be imported as `import SuperDebug from 'sveltekit-superforms/SuperDebug.svelte';`
+- Fixed `bigint` handling for Zod 4 and Valibot.
 
 ## [2.26.1] - 2025-06-05
 

package.json

@@ -169,7 +169,7 @@
 	},
 	"optionalDependencies": {
 		"@exodus/schemasafe": "^1.3.0",
-		"@gcornut/valibot-json-schema": "^0.31.0",
+		"@gcornut/valibot-json-schema": "^0.42.0",
 		"@sinclair/typebox": "^0.34.35",
 		"@typeschema/class-validator": "^0.3.0",
 		"@vinejs/vine": "^3.0.1",

pnpm-lock.yaml

@@ -28,6 +28,7 @@ type SupportedSchemas = GenericSchema | GenericSchemaAsync;
 const defaultOptions = {
 	strictObjectTypes: true,
 	dateStrategy: 'integer' as const,
+	bigintStrategy: 'integer' as const,
 	ignoreUnknownValidation: true,
 	customSchemaConversion: {
 		custom: () => ({}),

src/lib/adapters/valibot.ts

@@ -28,6 +28,9 @@ const defaultJSONSchemaOptions = {
 		if (def.type === 'date') {
 			ctx.jsonSchema.type = 'string';
 			ctx.jsonSchema.format = 'date-time';
+		} else if (def.type === 'bigint') {
+			ctx.jsonSchema.type = 'string';
+			ctx.jsonSchema.format = 'bigint';
 		}
 	}
 } satisfies Options;

src/lib/adapters/zod4.ts

@@ -117,12 +117,19 @@ function schemaTypes(
 	} else if (schema.format && conversionFormatTypes.includes(schema.format)) {
 		types.unshift(schema.format as SchemaType);
 
-		// Remove the integer type, as the schema format will be used
+		// For dates and int64 (bigint), remove the integer type, as the schema format will be used
 		// instead in the following cases
 		if (schema.format == 'unix-time' || schema.format == 'int64') {
 			const i = types.findIndex((t) => t == 'integer');
 			types.splice(i, 1);
 		}
+
+		// For bigint, remove the string type, as the schema format will be used
+		// instead in the following cases
+		if (schema.format == 'bigint') {
+			const i = types.findIndex((t) => t == 'string');
+			types.splice(i, 1);
+		}
 	}
 
 	if (schema.const && schema.const !== null && typeof schema.const !== 'function') {

src/lib/jsonSchema/schemaInfo.ts

@@ -470,6 +470,18 @@ describe('Valibot', () => {
 		).not.toThrow();
 	});
 
+	it('should handle bigint', async () => {
+		const schema = v.object({
+			id: v.bigint()
+		});
+		const data = new FormData();
+		data.set('id', '123456789123456789');
+
+		const form = await superValidate(data, valibot(schema));
+		expect(form.valid).toBe(true);
+		expect(form.data).toEqual({ id: BigInt('123456789123456789') });
+	});
+
 	/*
 	it('should work with FormPathLeaves and brand', async () => {
 		const schema = v.object({ id: v.brand(v.string(), 'Id') });
@@ -976,7 +988,7 @@ describe('Zod 4', () => {
 			'enumDef'
 		]);
 		expect(adapter.defaults).toEqual({
-			nativeEnumInt: 'Apple',
+			nativeEnumInt: 7,
 			nativeEnumString: 'GREEN',
 			enum: 'a',
 			enumDef: ''
@@ -1097,6 +1109,18 @@ describe('Zod 4', () => {
 		});
 	});
 
+	it('should work with bigint', async () => {
+		const schema = z4.object({
+			id: z4.bigint()
+		});
+		const data = new FormData();
+		data.set('id', '123456789123456789');
+
+		const form = await superValidate(data, zod4(schema));
+		expect(form.valid).toBe(true);
+		expect(form.data).toEqual({ id: BigInt('123456789123456789') });
+	});
+
 	schemaTest(zod4(schema), undefined, undefined, undefined, 'zod4');
 });