feat(medusa): Improve DX of validators extensions (#4397)

* feat(medusa): Allow to register extended validators seemlesly

* Create happy-points-yawn.md

* comment

.changeset/happy-points-yawn.md

@@ -0,0 +1,5 @@
+---
+"@medusajs/medusa": patch
+---
+
+feat(medusa): Allow to register extended validators seemlesly

packages/medusa/src/utils/__tests__/validator.spec.ts

@@ -0,0 +1,40 @@
+import { IsString } from "class-validator"
+import { AdminPostProductsReq as MedusaAdminPostProductsReq } from "../../api/routes/admin/products/create-product"
+import { registerOverriddenValidators, validator } from "../validator"
+
+class AdminPostProductsReq extends MedusaAdminPostProductsReq {
+  @IsString()
+  custom_attribute: string
+}
+
+describe("Validator", function () {
+  it("should override the original validator", async function () {
+    let err = await validator(MedusaAdminPostProductsReq, {
+      title: "test",
+    })
+      .then(() => void 0)
+      .catch((err) => err)
+
+    expect(err).not.toBeDefined()
+
+    registerOverriddenValidators(AdminPostProductsReq)
+
+    err = await validator(MedusaAdminPostProductsReq, {
+      title: "test",
+    })
+      .then(() => void 0)
+      .catch((err) => err)
+
+    expect(err).toBeDefined()
+    expect(err.message).toEqual("custom_attribute must be a string")
+
+    err = await validator(MedusaAdminPostProductsReq, {
+      title: "test",
+      custom_attribute: "test",
+    })
+      .then(() => void 0)
+      .catch((err) => err)
+
+    expect(err).not.toBeDefined()
+  })
+})

packages/medusa/src/utils/index.ts

@@ -13,3 +13,4 @@ export * from "./product-category"
 export * from "./remove-undefined-properties"
 export * from "./set-metadata"
 export * from "./validate-id"
+export { registerOverriddenValidators } from "./validator"

packages/medusa/src/utils/validator.ts

@@ -1,6 +1,34 @@
 import { ClassConstructor, plainToInstance } from "class-transformer"
 import { validate, ValidationError, ValidatorOptions } from "class-validator"
 import { MedusaError } from "medusa-core-utils"
+import { Constructor } from "@medusajs/types"
+
+const extendedValidators: Map<string, Constructor<any>> = new Map()
+
+/**
+ * When overriding a validator, you can register it to be used instead of the original one.
+ * For example, the place where you are overriding the core validator, you can call this function
+ * @example
+ * ```ts
+ * // /src/api/routes/admin/products/create-product.ts
+ * import { registerOverriddenValidators } from "@medusajs/medusa"
+ * import { AdminPostProductsReq as MedusaAdminPostProductsReq } from "@medusajs/medusa/dist/api/routes/admin/products/create-product"
+ * import { IsString } from "class-validator"
+ *
+ * class AdminPostProductsReq extends MedusaAdminPostProductsReq {
+ *    @IsString()
+ *    test: string
+ * }
+ *
+ * registerOverriddenValidators(AdminPostProductsReq)
+ * ```
+ * @param extendedValidator
+ */
+export function registerOverriddenValidators(
+  extendedValidator: Constructor<any>
+): void {
+  extendedValidators.set(extendedValidator.name, extendedValidator)
+}
 
 const reduceErrorMessages = (errs: ValidationError[]): string[] => {
   return errs.reduce((acc: string[], next) => {
@@ -22,6 +50,8 @@ export async function validator<T, V>(
   plain: V,
   config: ValidatorOptions = {}
 ): Promise<T> {
+  typedClass = extendedValidators.get(typedClass.name) ?? typedClass
+
   const toValidate = plainToInstance(typedClass, plain)
   // @ts-ignore
   const errors = await validate(toValidate, {