erp5_data_notebook bt5: External Method to Display Matplotlib Image.

mime_type for results for executed jupyter_code from JupyterCompile extension
has also been defined on the server side itself.

This would help server to have more command over what Content-Type  would be
displayed to jupyter frontend.

bt5/erp5_data_notebook/ExtensionTemplateItem/portal_components/extension.erp5.JupyterCompile.py

@@ -7,6 +7,8 @@ import sys
 import ast
 import types
 
+mime_type = 'text/plain'
+
 def Base_compileJupyterCode(self, jupyter_code, old_local_variable_dict):
   """
     Function to execute jupyter code and update the local_varibale dictionary.
@@ -146,6 +148,7 @@ def Base_compileJupyterCode(self, jupyter_code, old_local_variable_dict):
     'result_string': result_string,
     'local_variable_dict': local_variable_dict,
     'status': status,
+    'mime_type': mime_type,
     'evalue': evalue,
     'ename': ename,
     'traceback': tb_list,
@@ -174,4 +177,37 @@ def UpdateLocalVariableDict(self, existing_dict):
   for key, val in existing_dict['imports'].iteritems():
     new_dict['imports'][key] = val
   return new_dict
+
+def Base_displayMatplotlibImage(self, plot_object=None):
+  """
+  External function to display Matplotlib Plot objects to jupyter function.
+  
+  Parameters
+  ----------
+  
+  plot_object : Any matplotlib object from which we can create a plot.
+                Can be <matplotlib.lines.Line2D>, <matplotlib.text.Text>, etc.
+  
+  Output
+  -----
+  
+  Returns base64 encoded string of the plot on which it has been called.
+
+  """
+  if plot_object:
+    from io import BytesIO
+    import base64
+
+    # Create a ByteFile on the server which would be used to save the plot
+    figfile = BytesIO()
+    # Save plot as 'png' format in the ByteFile
+    plot_object.savefig(figfile, format='png')
+    figfile.seek(0)
+    # Encode the value in figfile to base64 string so as to serve it jupyter frontend
+    figdata_png = base64.b64encode(figfile.getvalue())
+    # Chanage global variable 'mime_type' to 'image/png'
+    global mime_type
+    mime_type = 'image/png'
+
+    return figdata_png
   
\ No newline at end of file

bt5/erp5_data_notebook/ExtensionTemplateItem/portal_components/extension.erp5.JupyterCompile.xml

@@ -46,9 +46,10 @@
             <key> <string>text_content_warning_message</string> </key>
             <value>
               <tuple>
-                <string>W: 73,  6: Use of exec (exec-used)</string>
-                <string>W:102,  6: Use of exec (exec-used)</string>
-                <string>W:108,  6: Use of exec (exec-used)</string>
+                <string>W: 75,  6: Use of exec (exec-used)</string>
+                <string>W:104,  6: Use of exec (exec-used)</string>
+                <string>W:110,  6: Use of exec (exec-used)</string>
+                <string>W:209,  4: Using the global statement (global-statement)</string>
               </tuple>
             </value>
         </item>

bt5/erp5_data_notebook/SkinTemplateItem/portal_skins/erp5_data_notebook/Base_displayMatplotlibImage.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="ExternalMethod" module="Products.ExternalMethod.ExternalMethod"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>_function</string> </key>
+            <value> <string>Base_displayMatplotlibImage</string> </value>
+        </item>
+        <item>
+            <key> <string>_module</string> </key>
+            <value> <string>JupyterCompile</string> </value>
+        </item>
+        <item>
+            <key> <string>id</string> </key>
+            <value> <string>Base_displayMatplotlibImage</string> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string></string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

bt5/erp5_data_notebook/SkinTemplateItem/portal_skins/erp5_data_notebook/Base_executeJupyter.xml

@@ -137,6 +137,7 @@ ename = final_result[\'ename\']\n
 evalue = final_result[\'evalue\']\n
 traceback = final_result[\'traceback\']\n
 status = final_result[\'status\']\n
+mime_type = final_result[\'mime_type\']\n
 \n
 # Call to function to update persistent mapping object with new local variables\n
 # and save the variables in the Active Result pertaining to the current Data Notebook\n
@@ -148,7 +149,8 @@ result = {\n
   u\'ename\': ename,\n
   u\'evalue\': evalue,\n
   u\'traceback\': traceback,\n
-  u\'status\': status\n
+  u\'status\': status,\n
+  u\'mime_type\': mime_type\n
 }\n
 \n
 # Catch exception while seriaizing the result to be passed to jupyter frontend\n