Improve type inference in generics

colinhacks · Mar 6, 2023 · 4d016b7 · 4d016b7
1 parent b276d71
commit 4d016b7
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Showing 5 changed files with 104 additions and 71 deletions.
diff --git a/deno/lib/__tests__/generics.test.ts b/deno/lib/__tests__/generics.test.ts
@@ -0,0 +1,28 @@
+// @ts-ignore TS6133
+import { expect } from "https://deno.land/x/expect@v0.2.6/mod.ts";
+const test = Deno.test;
+
+import { util } from "../helpers/util.ts";
+import * as z from "../index.ts";
+
+test("generics", () => {
+  async function stripOuter<TData extends z.ZodTypeAny>(
+    schema: TData,
+    url: string
+  ): Promise<TData["_output"]> {
+    const zStrippedResponse = z
+      .object({
+        topLevelKey: schema,
+      })
+      .transform((data) => {
+        return data.topLevelKey;
+      });
+
+    return fetch(url)
+      .then((response) => response.json())
+      .then((data) => zStrippedResponse.parse(data));
+  }
+
+  const result = stripOuter(z.number(), "");
+  util.assertEqual<typeof result, Promise<number>>(true);
+});
diff --git a/deno/lib/helpers/partialUtil.ts b/deno/lib/helpers/partialUtil.ts
@@ -3,6 +3,7 @@ import type {
   ZodNullable,
   ZodObject,
   ZodOptional,
+  ZodRawShape,
   ZodTuple,
   ZodTupleItems,
   ZodTypeAny,
@@ -34,33 +35,30 @@ export namespace partialUtil {
   //   ? "object" // T extends ZodOptional<any> // ? 'optional' // :
   //   : "rest"];
 
-  export type DeepPartial<T extends ZodTypeAny> = T extends ZodObject<
-    infer Shape,
-    infer Params,
-    infer Catchall
-  >
-    ? ZodObject<
-        { [k in keyof Shape]: ZodOptional<DeepPartial<Shape[k]>> },
-        Params,
-        Catchall
-      >
-    : T extends ZodArray<infer Type, infer Card>
-    ? ZodArray<DeepPartial<Type>, Card>
-    : T extends ZodOptional<infer Type>
-    ? ZodOptional<DeepPartial<Type>>
-    : T extends ZodNullable<infer Type>
-    ? ZodNullable<DeepPartial<Type>>
-    : T extends ZodTuple<infer Items>
-    ? {
-        [k in keyof Items]: Items[k] extends ZodTypeAny
-          ? DeepPartial<Items[k]>
-          : never;
-      } extends infer PI
-      ? PI extends ZodTupleItems
-        ? ZodTuple<PI>
+  export type DeepPartial<T extends ZodTypeAny> =
+    T extends ZodObject<ZodRawShape>
+      ? ZodObject<
+          { [k in keyof T["shape"]]: ZodOptional<DeepPartial<T["shape"][k]>> },
+          T["_def"]["unknownKeys"],
+          T["_def"]["catchall"]
+        >
+      : T extends ZodArray<infer Type, infer Card>
+      ? ZodArray<DeepPartial<Type>, Card>
+      : T extends ZodOptional<infer Type>
+      ? ZodOptional<DeepPartial<Type>>
+      : T extends ZodNullable<infer Type>
+      ? ZodNullable<DeepPartial<Type>>
+      : T extends ZodTuple<infer Items>
+      ? {
+          [k in keyof Items]: Items[k] extends ZodTypeAny
+            ? DeepPartial<Items[k]>
+            : never;
+        } extends infer PI
+        ? PI extends ZodTupleItems
+          ? ZodTuple<PI>
+          : never
         : never
-      : never
-    : T;
+      : T;
   //  {
   //     // optional: T extends ZodOptional<ZodTypeAny> ? T : ZodOptional<T>;
   //     // array: T extends ZodArray<infer Type> ? ZodArray<DeepPartial<Type>> : never;

diff --git a/playground.ts b/playground.ts
@@ -1,20 +1,2 @@
 import { z } from "./src";
-
-async function stripOuter<TData extends z.ZodTypeAny>(
-  schema: TData,
-  url: string
-): Promise<TData["_output"]> {
-  const zStrippedResponse = z
-    .object({
-      topLevelKey: schema,
-    })
-    .transform((data) => {
-      return data.topLevelKey;
-    });
-
-  return fetch(url)
-    .then((response) => response.json())
-    .then((data) => zStrippedResponse.parse(data));
-}
-
-type asdf = Omit<{ a: string }, "b">;
+z;
diff --git a/src/__tests__/generics.test.ts b/src/__tests__/generics.test.ts
@@ -0,0 +1,27 @@
+// @ts-ignore TS6133
+import { expect, test } from "@jest/globals";
+
+import { util } from "../helpers/util";
+import * as z from "../index";
+
+test("generics", () => {
+  async function stripOuter<TData extends z.ZodTypeAny>(
+    schema: TData,
+    url: string
+  ): Promise<TData["_output"]> {
+    const zStrippedResponse = z
+      .object({
+        topLevelKey: schema,
+      })
+      .transform((data) => {
+        return data.topLevelKey;
+      });
+
+    return fetch(url)
+      .then((response) => response.json())
+      .then((data) => zStrippedResponse.parse(data));
+  }
+
+  const result = stripOuter(z.number(), "");
+  util.assertEqual<typeof result, Promise<number>>(true);
+});
diff --git a/src/helpers/partialUtil.ts b/src/helpers/partialUtil.ts
@@ -3,6 +3,7 @@ import type {
   ZodNullable,
   ZodObject,
   ZodOptional,
+  ZodRawShape,
   ZodTuple,
   ZodTupleItems,
   ZodTypeAny,
@@ -34,33 +35,30 @@ export namespace partialUtil {
   //   ? "object" // T extends ZodOptional<any> // ? 'optional' // :
   //   : "rest"];
 
-  export type DeepPartial<T extends ZodTypeAny> = T extends ZodObject<
-    infer Shape,
-    infer Params,
-    infer Catchall
-  >
-    ? ZodObject<
-        { [k in keyof Shape]: ZodOptional<DeepPartial<Shape[k]>> },
-        Params,
-        Catchall
-      >
-    : T extends ZodArray<infer Type, infer Card>
-    ? ZodArray<DeepPartial<Type>, Card>
-    : T extends ZodOptional<infer Type>
-    ? ZodOptional<DeepPartial<Type>>
-    : T extends ZodNullable<infer Type>
-    ? ZodNullable<DeepPartial<Type>>
-    : T extends ZodTuple<infer Items>
-    ? {
-        [k in keyof Items]: Items[k] extends ZodTypeAny
-          ? DeepPartial<Items[k]>
-          : never;
-      } extends infer PI
-      ? PI extends ZodTupleItems
-        ? ZodTuple<PI>
+  export type DeepPartial<T extends ZodTypeAny> =
+    T extends ZodObject<ZodRawShape>
+      ? ZodObject<
+          { [k in keyof T["shape"]]: ZodOptional<DeepPartial<T["shape"][k]>> },
+          T["_def"]["unknownKeys"],
+          T["_def"]["catchall"]
+        >
+      : T extends ZodArray<infer Type, infer Card>
+      ? ZodArray<DeepPartial<Type>, Card>
+      : T extends ZodOptional<infer Type>
+      ? ZodOptional<DeepPartial<Type>>
+      : T extends ZodNullable<infer Type>
+      ? ZodNullable<DeepPartial<Type>>
+      : T extends ZodTuple<infer Items>
+      ? {
+          [k in keyof Items]: Items[k] extends ZodTypeAny
+            ? DeepPartial<Items[k]>
+            : never;
+        } extends infer PI
+        ? PI extends ZodTupleItems
+          ? ZodTuple<PI>
+          : never
         : never
-      : never
-    : T;
+      : T;
   //  {
   //     // optional: T extends ZodOptional<ZodTypeAny> ? T : ZodOptional<T>;
   //     // array: T extends ZodArray<infer Type> ? ZodArray<DeepPartial<Type>> : never;