feat: implement nin operator #297

datagateway_api/src/datagateway_api/icat/filters.py

@@ -90,6 +90,20 @@ def create_filter(self):
             where_filter = self.create_condition(self.field, "in", self.value)
         elif self.operation == "inq":
             self.operation = "in"
+            where_filter = self.create_filter()
+        elif self.operation == "nin":
+            # Convert self.value into a string with brackets equivalent to tuple format.
+            # Cannot convert straight to tuple as single element tuples contain a
+            # trailing comma which Python ICAT/JPQL doesn't accept
+            self.value = str(self.value).replace("[", "(").replace("]", ")")
+
+            # DataGateway Search can send requests with blank lists. Adding NULL to the
+            # filter prevents the API from returning a 500. An empty list will be
+            # returned instead, equivalent to the DB backend
+            if self.value == "()":
+                self.value = "(NULL)"
+
+            where_filter = self.create_condition(self.field, "not in", self.value)
         elif self.operation == "between":
             where_filter = self.create_condition(
                 self.field, "between", f"'{self.value[0]}' and '{self.value[1]}'",