types(validation): support function for validator message property,…

… and add support for accessing validator `reason`

Fix #14496

test/types/schema.test.ts

@@ -1407,3 +1407,20 @@ function gh14235() {
   userSchema.omit<Omit<IUser, 'age'>>(['age']);
 }
 
+function gh14496() {
+  const schema = new Schema({
+    name: {
+      type: String
+    }
+  });
+  schema.path('name').validate({
+    validator: () => {
+      throw new Error('Oops!');
+    },
+    // `errors['name']` will be "Oops!"
+    message: (props) => {
+      expectType<Error | undefined>(props.reason);
+      return 'test';
+    }
+  });
+}

types/schematypes.d.ts

@@ -193,9 +193,10 @@ declare module 'mongoose' {
   }
 
   interface Validator<DocType = any> {
-    message?: string;
+    message?: string | ((props: ValidatorProps) => string);
     type?: string;
     validator?: ValidatorFunction<DocType>;
+    reason?: Error;
   }
 
   type ValidatorFunction<DocType = any> = (this: DocType, value: any, validatorProperties?: Validator) => any;

types/validation.d.ts

@@ -6,6 +6,7 @@ declare module 'mongoose' {
     path: string;
     fullPath: string;
     value: any;
+    reason?: Error;
   }
 
   interface ValidatorMessageFn {