[OSDEV-1778] Fix the validation for number_of_workers field in POST, PATCH production locations API

doc/release/RELEASE-NOTES.md

@@ -76,6 +76,7 @@ This project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html
 * [OSDEV-1589](https://opensupplyhub.atlassian.net/browse/OSDEV-1589) - Fixed layout issue on new `contribute` page.
 * [OSDEV-1739](https://opensupplyhub.atlassian.net/browse/OSDEV-1739) - Applied state cleanup on modal unmount to prevent the same dialog from appearing when clicking on a different production location.
 * [OSDEV-1744](https://opensupplyhub.atlassian.net/browse/OSDEV-1744) - Fixed the issue where the text `by user ID:` appeared even when `user_id` was `null` in Contribution Record page.
+* [OSDEV-1778](https://opensupplyhub.atlassian.net/browse/OSDEV-1778) - Fixed the validation for number of workers field in POST, PATH production locations API. The min field must be less than or equal to the max field.
 
 ### What's new
 * [OSDEV-1662](https://opensupplyhub.atlassian.net/browse/OSDEV-1662) - Added a new field, `action_perform_by`, to the moderation event. This data appears on the Contribution Record page when a moderator perform any actions like `APPROVED` or `REJECTED`.

src/django/api/serializers/v1/number_of_workers_serializer.py

@@ -7,16 +7,34 @@ class NumberOfWorkersSerializer(serializers.Serializer):
         required=True,
         error_messages={
             'required': 'The min field is required!',
+            'invalid': 'The min field must be an integer.'
         }
     )
     max = serializers.IntegerField(
         min_value=1,
         required=True,
         error_messages={
             'required': 'The max field is required!',
+            'invalid': 'The max field must be an integer.'
         }
     )
 
+    def validate(self, data):
+        min_value = data.get('min')
+        max_value = data.get('max')
+
+        if (
+            min_value is not None
+            and max_value is not None
+            and min_value > max_value
+        ):
+            raise serializers.ValidationError(
+                {"min": ('The min field must be less than or equal'
+                         ' to the max field.')}
+            )
+
+        return data
+
     @staticmethod
     def validate_object(value):
         return isinstance(value, dict)