Add the base64 string encoding for pdf and png graphic files.

controllers/graphs.py

@@ -2,6 +2,7 @@
 """ Controllers for building graphs using pandas library
 
 """
+import base64
 import matplotlib
 matplotlib.use('Agg')
 import matplotlib.pyplot as plt
@@ -90,4 +91,9 @@ def index():
     extension = request.extension
     fmt = "svg" if extension == "html" else extension
 
-    return dict(data=savefig(ax.get_figure(), fmt))
+    # base64 string encoding
+    data = savefig(ax.get_figure(), fmt)
+    if fmt in ("pdf", "png"):
+        data = base64.b64encode(data)
+
+    return dict(data=data)