#119: Set response body keys based on field name rather than table name

- This change also allows related entities to be retrieved on with plural field name
- Related entities with a singular field name also typically have a foreign key attribute in the class. When an include filter is used in this situation, the included entity will be returned in the response body, rather than the foreign key. This had a better outcome than I thought it would've done :)

datagateway_api/common/database/models.py

@@ -114,17 +114,17 @@ def _nest_dictionary_include(self, dictionary, include):
         """
         related_entity = self.get_related_entity(list(include)[0])
         if not isinstance(related_entity, InstrumentedList):
-            dictionary[related_entity.__tablename__] = related_entity.to_nested_dict(
-                include[list(include)[0]],
-            )
+            dictionary[
+                related_entity.__singularfieldname__
+            ] = related_entity.to_nested_dict(include[list(include)[0]])
         else:
             for entity in related_entity:
-                if entity.__tablename__ in dictionary.keys():
-                    dictionary[entity.__tablename__].append(
+                if entity.__pluralfieldname__ in dictionary.keys():
+                    dictionary[entity.__pluralfieldname__].append(
                         entity.to_nested_dict(include[list(include)[0]]),
                     )
                 else:
-                    dictionary[entity.__tablename__] = [
+                    dictionary[entity.__pluralfieldname__] = [
                         entity.to_nested_dict(include[list(include)[0]]),
                     ]
 
@@ -138,13 +138,13 @@ def _nest_string_include(self, dictionary, include):
         """
         related_entity = self.get_related_entity(include)
         if not isinstance(related_entity, InstrumentedList):
-            dictionary[related_entity.__tablename__] = related_entity.to_dict()
+            dictionary[related_entity.__singularfieldname__] = related_entity.to_dict()
         else:
             for entity in related_entity:
-                if entity.__tablename__ in dictionary.keys():
-                    dictionary[entity.__tablename__].append(entity.to_dict())
+                if entity.__pluralfieldname__ in dictionary.keys():
+                    dictionary[entity.__pluralfieldname__].append(entity.to_dict())
                 else:
-                    dictionary[entity.__tablename__] = [entity.to_dict()]
+                    dictionary[entity.__pluralfieldname__] = [entity.to_dict()]
 
     def get_related_entity(self, entity):
         """
@@ -153,7 +153,7 @@ def get_related_entity(self, entity):
         :return: The entity
         """
         try:
-            return getattr(self, entity)
+            return getattr(self, entity if entity[-1] == "s" else entity.upper())
         except AttributeError:
             raise FilterError(f" No related entity: {entity}")