Add get_file_data() function to datastore

bin/datastore.py

@@ -589,7 +589,33 @@ class Datastore:
 			# We do not commit if we've been passed a cursor, instead
 			# we assume that we are in the middle of a transaction
 
+	def get_file_data(self, path, cursor = None):
+		"""
+		Retrieve arbitrary data associated with a file.
+		"""
 
+		if cursor is None:
+			cur = self.conn.cursor()
+		else:
+			cur = cursor
+
+		realpath = configuration.translate_path(path)
+		hash = file_hash(realpath)
+
+		qry = """
+			SELECT data
+			FROM file_data
+			WHERE hash = %s;
+		"""
+
+		cur.execute(qry, (hash,))
+		res = cur.fetchone()
+
+		if cursor is None:
+			self.maybe_commit()
+			# We do not commit if we've been passed a cursor, instead
+			# we assume that we are in the middle of a transaction
+		return res[0]
 
 	def surveys (self, include_archived = False):
 		"""