Allow coercion when given union of coercible values

package.json

@@ -69,6 +69,7 @@
     "superjson": "^1.12.3",
     "ts-jest": "^29.1.0",
     "ts-node": "^10.9.1",
-    "typescript": "^5.0.4"
+    "typescript": "^5.0.4",
+    "zod": "^3.22.4"
   }
 }

src/adapters/node-http/core.ts

@@ -20,6 +20,7 @@ import { normalizePath } from '../../utils/path';
 import { getInputOutputParsers } from '../../utils/procedure';
 import {
   instanceofZodTypeCoercible,
+  instanceofZodTypeKind,
   instanceofZodTypeLikeVoid,
   instanceofZodTypeObject,
   unwrapZodType,
@@ -118,7 +119,14 @@ export const createOpenApiNodeHttpHandler = <
         if (instanceofZodTypeObject(unwrappedSchema)) {
           Object.values(unwrappedSchema.shape).forEach((shapeSchema) => {
             const unwrappedShapeSchema = unwrapZodType(shapeSchema, false);
-            if (instanceofZodTypeCoercible(unwrappedShapeSchema)) {
+
+            if (instanceofZodTypeKind(unwrappedShapeSchema, z.ZodFirstPartyTypeKind.ZodUnion)) {
+              unwrappedShapeSchema.options.forEach((option) => {
+                if (instanceofZodTypeCoercible(option)) {
+                  option._def.coerce = true;
+                }
+              });
+            } else if (instanceofZodTypeCoercible(unwrappedShapeSchema)) {
               unwrappedShapeSchema._def.coerce = true;
             }
           });

src/generator/paths.ts

@@ -94,7 +94,11 @@ export const getOpenApiPathsObject = (
                   ) || []),
                 ],
               }),
-          responses: getResponsesObject(outputParser, openapi.example?.response, openapi.responseHeaders),
+          responses: getResponsesObject(
+            outputParser,
+            openapi.example?.response,
+            openapi.responseHeaders,
+          ),
           ...(openapi.deprecated ? { deprecated: openapi.deprecated } : {}),
         },
       };

src/generator/schema.ts

@@ -189,7 +189,7 @@ export const errorResponseObject: OpenAPIV3.ResponseObject = {
 export const getResponsesObject = (
   schema: unknown,
   example: Record<string, any> | undefined,
-  headers: Record<string, OpenAPIV3.HeaderObject | OpenAPIV3.ReferenceObject> | undefined
+  headers: Record<string, OpenAPIV3.HeaderObject | OpenAPIV3.ReferenceObject> | undefined,
 ): OpenAPIV3.ResponsesObject => {
   if (!instanceofZodType(schema)) {
     throw new TRPCError({

src/utils/zod.ts

@@ -7,7 +7,7 @@ export const instanceofZodType = (type: any): type is z.ZodTypeAny => {
 export const instanceofZodTypeKind = <Z extends z.ZodFirstPartyTypeKind>(
   type: z.ZodTypeAny,
   zodTypeKind: Z,
-): type is InstanceType<typeof z[Z]> => {
+): type is InstanceType<(typeof z)[Z]> => {
   return type?._def?.typeName === zodTypeKind;
 };
 
@@ -106,6 +106,13 @@ export type ZodTypeCoercible = z.ZodNumber | z.ZodBoolean | z.ZodBigInt | z.ZodD
 
 export const instanceofZodTypeCoercible = (_type: z.ZodTypeAny): _type is ZodTypeCoercible => {
   const type = unwrapZodType(_type, false);
+
+  if (instanceofZodTypeKind(type, z.ZodFirstPartyTypeKind.ZodUnion)) {
+    return type._def.options.every(
+      (option) => instanceofZodTypeLikeString(option) || instanceofZodTypeCoercible(option),
+    );
+  }
+
   return (
     instanceofZodTypeKind(type, z.ZodFirstPartyTypeKind.ZodNumber) ||
     instanceofZodTypeKind(type, z.ZodFirstPartyTypeKind.ZodBoolean) ||

test/adapters/standalone.test.ts

@@ -1194,6 +1194,7 @@ describe('standalone adapter', () => {
     // @ts-expect-error - hack to disable zodSupportsCoerce
     // eslint-disable-next-line import/namespace
     zodUtils.zodSupportsCoerce = false;
+
     {
       const appRouter = t.router({
         plusOne: t.procedure
@@ -1225,6 +1226,7 @@ describe('standalone adapter', () => {
 
       close();
     }
+
     // @ts-expect-error - hack to re-enable zodSupportsCoerce
     // eslint-disable-next-line import/namespace
     zodUtils.zodSupportsCoerce = true;