#154: Add function to get instance of DB model entity from a name

common/database/models.py

@@ -20,7 +20,7 @@
 from sqlalchemy.orm import relationship
 from sqlalchemy.orm.collections import InstrumentedList
 
-from common.exceptions import FilterError, DatabaseError
+from common.exceptions import FilterError, DatabaseError, ApiError
 
 Base = declarative_base()
 
@@ -58,6 +58,25 @@ class EntityHelper(object):
     EntityHelper class that contains methods to be shared across all entities
     """
 
+    @staticmethod
+    def get_entity_object_from_name(entity_name):
+        """
+        From an entity name, this function gets a Python version of that entity for the
+        database backend
+
+        :param entity_name: Name of the entity to fetch a version from this model
+        :type entity_name: :class:`str`
+        :return: Object of the entity requested (e.g. 
+            :class:`common.database.models.INVESTIGATIONINSTRUMENT`)
+        :raises: KeyError: If an entity model cannot be found as a class in this model
+        """
+        try:
+            return globals()[entity_name.upper()]
+        except KeyError:
+            raise ApiError(
+                f"Entity class cannot be found. Please create a class for {entity_name}"
+            )
+
     def to_dict(self):
         """
         Turns the columns and values of an entity into a dictionary