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

doc/release/RELEASE-NOTES.md

@@ -48,6 +48,7 @@ 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.
 * [OSDEV-1779](https://opensupplyhub.atlassian.net/browse/OSDEV-1779) - SLC. Made Parent Company field as regular text field and apply snake_case keys to standard keys (e.g. `location_type`, `number_of_workers`, `parent_company`, `processing_type` and `product_type`) in request payload from production location info page to conform API specs.
 * [OSDEV-1745](https://opensupplyhub.atlassian.net/browse/OSDEV-1745) - The `Search by Name and Address` tab was defined as default on the Production Location Search page.
 

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

@@ -17,6 +17,44 @@ class NumberOfWorkersSerializer(serializers.Serializer):
         }
     )
 
+    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)
+
+    def to_internal_value(self, data):
+        errors = []
+
+        if not isinstance(data.get('min'), int):
+            errors.append({
+                "field": "min",
+                "detail":
+                    "The min field must be an integer."
+            })
+
+        if not isinstance(data.get('max'), int):
+            errors.append({
+                "field": "max",
+                "detail":
+                    "The max field must be an integer."
+            })
+
+        if len(errors) > 0:
+            raise serializers.ValidationError(errors)
+
+        return super().to_internal_value(data)