Merge pull request #727 from DenisFrezzato/improve-refinement-type

Improve refine with type guards

deno/lib/__tests__/refine.test.ts

@@ -2,6 +2,7 @@
 import { expect } from "https://deno.land/x/[email protected]/mod.ts";
 const test = Deno.test;
 
+import { util } from "../helpers/util.ts";
 import * as z from "../index.ts";
 import { ZodIssueCode } from "../ZodError.ts";
 
@@ -49,6 +50,38 @@ test("refinement 2", () => {
   ).toThrow();
 });
 
+test("refinement type guard", () => {
+  const validationSchema = z.object({
+    a: z.string().refine((s): s is "a" => s === "a"),
+  });
+  type Schema = z.infer<typeof validationSchema>;
+
+  const f1: util.AssertEqual<"a", Schema["a"]> = true;
+  f1;
+  const f2: util.AssertEqual<"string", Schema["a"]> = false;
+  f2;
+});
+
+test("refinement Promise", async () => {
+  const validationSchema = z
+    .object({
+      email: z.string().email(),
+      password: z.string(),
+      confirmPassword: z.string(),
+    })
+    .refine(
+      (data) =>
+        Promise.resolve().then(() => data.password === data.confirmPassword),
+      "Both password and confirmation must match"
+    );
+
+  await validationSchema.parseAsync({
+    email: "[email protected]",
+    password: "password",
+    confirmPassword: "password",
+  });
+});
+
 test("custom path", async () => {
   const result = await z
     .object({

deno/lib/types.ts

@@ -225,8 +225,16 @@ export abstract class ZodType<
   /** The .check method has been removed in Zod 3. For details see https://github.com/colinhacks/zod/tree/v3. */
   check!: never;
 
-  refine<Func extends (arg: Output) => any>(
-    check: Func,
+  refine<RefinedOutput extends Output>(
+    check: (arg: Output) => arg is RefinedOutput,
+    message?: string | CustomErrorParams | ((arg: Output) => CustomErrorParams)
+  ): ZodEffects<this, RefinedOutput, RefinedOutput>;
+  refine(
+    check: (arg: Output) => unknown | Promise<unknown>,
+    message?: string | CustomErrorParams | ((arg: Output) => CustomErrorParams)
+  ): ZodEffects<this, Output, Input>;
+  refine(
+    check: (arg: Output) => unknown,
     message?: string | CustomErrorParams | ((arg: Output) => CustomErrorParams)
   ): ZodEffects<this, Output, Input> {
     const getIssueProperties: any = (val: Output) => {
@@ -264,8 +272,16 @@ export abstract class ZodType<
     });
   }
 
+  refinement<RefinedOutput extends Output>(
+    check: (arg: Output) => arg is RefinedOutput,
+    refinementData: IssueData | ((arg: Output, ctx: RefinementCtx) => IssueData)
+  ): ZodEffects<this, RefinedOutput, RefinedOutput>;
   refinement(
-    check: (arg: Output) => any,
+    check: (arg: Output) => boolean,
+    refinementData: IssueData | ((arg: Output, ctx: RefinementCtx) => IssueData)
+  ): ZodEffects<this, Output, Input>;
+  refinement(
+    check: (arg: Output) => unknown,
     refinementData: IssueData | ((arg: Output, ctx: RefinementCtx) => IssueData)
   ): ZodEffects<this, Output, Input> {
     return this._refinement((val, ctx) => {
@@ -289,7 +305,7 @@ export abstract class ZodType<
       schema: this,
       typeName: ZodFirstPartyTypeKind.ZodEffects,
       effect: { type: "refinement", refinement },
-    }) as any;
+    });
   }
   superRefine = this._refinement;
 

src/__tests__/refine.test.ts

@@ -1,6 +1,7 @@
 // @ts-ignore TS6133
 import { expect, test } from "@jest/globals";
 
+import { util } from "../helpers/util";
 import * as z from "../index";
 import { ZodIssueCode } from "../ZodError";
 
@@ -48,6 +49,38 @@ test("refinement 2", () => {
   ).toThrow();
 });
 
+test("refinement type guard", () => {
+  const validationSchema = z.object({
+    a: z.string().refine((s): s is "a" => s === "a"),
+  });
+  type Schema = z.infer<typeof validationSchema>;
+
+  const f1: util.AssertEqual<"a", Schema["a"]> = true;
+  f1;
+  const f2: util.AssertEqual<"string", Schema["a"]> = false;
+  f2;
+});
+
+test("refinement Promise", async () => {
+  const validationSchema = z
+    .object({
+      email: z.string().email(),
+      password: z.string(),
+      confirmPassword: z.string(),
+    })
+    .refine(
+      (data) =>
+        Promise.resolve().then(() => data.password === data.confirmPassword),
+      "Both password and confirmation must match"
+    );
+
+  await validationSchema.parseAsync({
+    email: "[email protected]",
+    password: "password",
+    confirmPassword: "password",
+  });
+});
+
 test("custom path", async () => {
   const result = await z
     .object({

src/types.ts

@@ -225,8 +225,16 @@ export abstract class ZodType<
   /** The .check method has been removed in Zod 3. For details see https://github.com/colinhacks/zod/tree/v3. */
   check!: never;
 
-  refine<Func extends (arg: Output) => any>(
-    check: Func,
+  refine<RefinedOutput extends Output>(
+    check: (arg: Output) => arg is RefinedOutput,
+    message?: string | CustomErrorParams | ((arg: Output) => CustomErrorParams)
+  ): ZodEffects<this, RefinedOutput, RefinedOutput>;
+  refine(
+    check: (arg: Output) => unknown | Promise<unknown>,
+    message?: string | CustomErrorParams | ((arg: Output) => CustomErrorParams)
+  ): ZodEffects<this, Output, Input>;
+  refine(
+    check: (arg: Output) => unknown,
     message?: string | CustomErrorParams | ((arg: Output) => CustomErrorParams)
   ): ZodEffects<this, Output, Input> {
     const getIssueProperties: any = (val: Output) => {
@@ -264,8 +272,16 @@ export abstract class ZodType<
     });
   }
 
+  refinement<RefinedOutput extends Output>(
+    check: (arg: Output) => arg is RefinedOutput,
+    refinementData: IssueData | ((arg: Output, ctx: RefinementCtx) => IssueData)
+  ): ZodEffects<this, RefinedOutput, RefinedOutput>;
   refinement(
-    check: (arg: Output) => any,
+    check: (arg: Output) => boolean,
+    refinementData: IssueData | ((arg: Output, ctx: RefinementCtx) => IssueData)
+  ): ZodEffects<this, Output, Input>;
+  refinement(
+    check: (arg: Output) => unknown,
     refinementData: IssueData | ((arg: Output, ctx: RefinementCtx) => IssueData)
   ): ZodEffects<this, Output, Input> {
     return this._refinement((val, ctx) => {
@@ -289,7 +305,7 @@ export abstract class ZodType<
       schema: this,
       typeName: ZodFirstPartyTypeKind.ZodEffects,
       effect: { type: "refinement", refinement },
-    }) as any;
+    });
   }
   superRefine = this._refinement;