Allow creation of discriminated unions with a readonly array of options (#3535)

Signed-off-by: Andrew Haines <andrew@haines.org.nz>

Author: haines

deno/lib/__tests__/discriminated-unions.test.ts

@@ -308,3 +308,14 @@ test("optional and nullable", () => {
   if (value.key === "b") value.b;
   if (value.key === null) value.b;
 });
+
+test("readonly array of options", () => {
+  const options = [
+    z.object({ type: z.literal("x"), val: z.literal(1) }),
+    z.object({ type: z.literal("y"), val: z.literal(2) }),
+  ] as const;
+
+  expect(
+    z.discriminatedUnion("type", options).parse({ type: "x", val: 1 })
+  ).toEqual({ type: "x", val: 1 });
+});

deno/lib/types.ts

@@ -3165,7 +3165,7 @@ export type ZodDiscriminatedUnionOption<Discriminator extends string> =
 
 export interface ZodDiscriminatedUnionDef<
   Discriminator extends string,
-  Options extends ZodDiscriminatedUnionOption<string>[] = ZodDiscriminatedUnionOption<string>[]
+  Options extends readonly ZodDiscriminatedUnionOption<string>[] = ZodDiscriminatedUnionOption<string>[]
 > extends ZodTypeDef {
   discriminator: Discriminator;
   options: Options;
@@ -3175,7 +3175,7 @@ export interface ZodDiscriminatedUnionDef<
 
 export class ZodDiscriminatedUnion<
   Discriminator extends string,
-  Options extends ZodDiscriminatedUnionOption<Discriminator>[]
+  Options extends readonly ZodDiscriminatedUnionOption<Discriminator>[]
 > extends ZodType<
   output<Options[number]>,
   ZodDiscriminatedUnionDef<Discriminator, Options>,
@@ -3245,7 +3245,7 @@ export class ZodDiscriminatedUnion<
    */
   static create<
     Discriminator extends string,
-    Types extends [
+    Types extends readonly [
       ZodDiscriminatedUnionOption<Discriminator>,
       ...ZodDiscriminatedUnionOption<Discriminator>[]
     ]

src/__tests__/discriminated-unions.test.ts

@@ -307,3 +307,14 @@ test("optional and nullable", () => {
   if (value.key === "b") value.b;
   if (value.key === null) value.b;
 });
+
+test("readonly array of options", () => {
+  const options = [
+    z.object({ type: z.literal("x"), val: z.literal(1) }),
+    z.object({ type: z.literal("y"), val: z.literal(2) }),
+  ] as const;
+
+  expect(
+    z.discriminatedUnion("type", options).parse({ type: "x", val: 1 })
+  ).toEqual({ type: "x", val: 1 });
+});

src/types.ts

@@ -3165,7 +3165,7 @@ export type ZodDiscriminatedUnionOption<Discriminator extends string> =
 
 export interface ZodDiscriminatedUnionDef<
   Discriminator extends string,
-  Options extends ZodDiscriminatedUnionOption<string>[] = ZodDiscriminatedUnionOption<string>[]
+  Options extends readonly ZodDiscriminatedUnionOption<string>[] = ZodDiscriminatedUnionOption<string>[]
 > extends ZodTypeDef {
   discriminator: Discriminator;
   options: Options;
@@ -3175,7 +3175,7 @@ export interface ZodDiscriminatedUnionDef<
 
 export class ZodDiscriminatedUnion<
   Discriminator extends string,
-  Options extends ZodDiscriminatedUnionOption<Discriminator>[]
+  Options extends readonly ZodDiscriminatedUnionOption<Discriminator>[]
 > extends ZodType<
   output<Options[number]>,
   ZodDiscriminatedUnionDef<Discriminator, Options>,
@@ -3245,7 +3245,7 @@ export class ZodDiscriminatedUnion<
    */
   static create<
     Discriminator extends string,
-    Types extends [
+    Types extends readonly [
       ZodDiscriminatedUnionOption<Discriminator>,
       ...ZodDiscriminatedUnionOption<Discriminator>[]
     ]