feat: Admin shipping options routes to Typescript (#891)

packages/medusa/src/utils/validators/is-boolean.ts

@@ -0,0 +1,14 @@
+// Util function defining the transformation of booleans when part of req.query
+// e.g. /admin/shipping-options?is_return=false -> false
+//
+// We've previously been using @Type(() => Boolean), but this will always return true for strings.
+// See https://github.com/typestack/class-transformer/issues/676
+// and https://github.com/typestack/class-transformer/issues/306
+//
+// The solution here is stolen from: https://github.com/typestack/class-transformer/issues/676#issuecomment-822699830
+export const optionalBooleanMapper = new Map([
+  ["undefined", undefined],
+  ["null", null],
+  ["true", true],
+  ["false", false],
+])