[Cherry-pick] Provide a strategy for host integrator's to set the python template at startup

src/DynamoCore/Models/DynamoModel.cs

@@ -521,6 +521,7 @@ public struct DefaultStartConfiguration : IStartConfiguration
             public IEnumerable<IExtension> Extensions { get; set; }
             public TaskProcessMode ProcessMode { get; set; }
             public bool IsHeadless { get; set; }
+            public string PythonTemplatePath { get; set; }
         }
 
         /// <summary>
@@ -636,21 +637,50 @@ protected DynamoModel(IStartConfiguration config)
             var userDataFolder = pathManager.GetUserDataFolder(); // Get the default user data path
             AddPackagePath(userDataFolder);
 
-            // Check if the Python template file specified in the settings file exists & it's not empty
-            // If not, check the default filepath for the Python template (userDataFolder\PythonTemplate.py).
-            // If that doesn't exist either or is empty, Dynamo falls back to the hard-coded Python script template.
-            // We log the behaviour to make it easy for users to troubleshoot this.
+            // Load Python Template
+            // The loading pattern is conducted in the following order
+            // 1) Set from DynamoSettings.XML
+            // 2) Set from API via the configuration file
+            // 3) Set from PythonTemplate.py located in 'C:\Users\USERNAME\AppData\Roaming\Dynamo\Dynamo Core\2.X'
+            // 4) Set from OOTB hard-coded default template
+
+            // If a custom python template path doesn't already exists in the DynamoSettings.xml
             if (string.IsNullOrEmpty(PreferenceSettings.PythonTemplateFilePath) || !File.Exists(PreferenceSettings.PythonTemplateFilePath))
             {
-                if (string.IsNullOrEmpty(pathManager.PythonTemplateFilePath) || !File.Exists(pathManager.PythonTemplateFilePath))
-                    Logger.Log(Resources.PythonTemplateInvalid);
+                // To supply a custom python template host integrators should supply a 'DefaultStartConfiguration' config file
+                // or create a new struct that inherits from 'DefaultStartConfiguration' making sure to set the 'PythonTemplatePath'
+                // while passing the config to the 'DynamoModel' constructor.
+                if (config is DefaultStartConfiguration)
+                {
+                    var configurationSettings = (DefaultStartConfiguration)config;
+                    var templatePath = configurationSettings.PythonTemplatePath;
+
+                    // If a custom python template path was set in the config apply that template
+                    if (!string.IsNullOrEmpty(templatePath) && File.Exists(templatePath))
+                    {
+                        PreferenceSettings.PythonTemplateFilePath = templatePath;
+                        Logger.Log(Resources.PythonTemplateDefinedByHost + " : " + PreferenceSettings.PythonTemplateFilePath);
+                    }
+
+                    // Otherwise fallback to the default
+                    else
+                    {
+                        SetDefaultPythonTemplate();
+                    }
+                }
+
                 else
                 {
-                    PreferenceSettings.PythonTemplateFilePath = pathManager.PythonTemplateFilePath;
-                    Logger.Log(Resources.PythonTemplateDefaultFile + " : " + pathManager.PythonTemplateFilePath);
+                    // Fallback to the default
+                    SetDefaultPythonTemplate();
                 }
             }
-            else Logger.Log(Resources.PythonTemplateUserFile + " : " + pathManager.PythonTemplateFilePath);
+
+            else
+            {
+                // A custom python template path already exists in the DynamoSettings.xml
+                Logger.Log(Resources.PythonTemplateUserFile + " : " + PreferenceSettings.PythonTemplateFilePath);
+            }
 
             pathManager.Preferences = PreferenceSettings;
 
@@ -779,6 +809,23 @@ protected DynamoModel(IStartConfiguration config)
              DynamoReady(new ReadyParams(this));
         }
 
+        private void SetDefaultPythonTemplate()
+        {
+            // First check if the default python template is overridden by a PythonTemplate.py file in AppData
+            // This file is always named accordingly and located in 'C:\Users\USERNAME\AppData\Roaming\Dynamo\Dynamo Core\2.X'
+            if (!string.IsNullOrEmpty(pathManager.PythonTemplateFilePath) && File.Exists(pathManager.PythonTemplateFilePath))
+            {
+                PreferenceSettings.PythonTemplateFilePath = pathManager.PythonTemplateFilePath;
+                Logger.Log(Resources.PythonTemplateAppData + " : " + PreferenceSettings.PythonTemplateFilePath);
+            }
+
+            // Otherwise the OOTB hard-coded template is applied
+            else
+            {
+                Logger.Log(Resources.PythonTemplateDefaultFile);
+            }
+        }
+
         private void DynamoReadyExtensionHandler(ReadyParams readyParams, IEnumerable<IExtension> extensions) {
 
             foreach (var ext in extensions)

src/DynamoCore/Properties/Resources.en-US.resx

@@ -688,4 +688,16 @@ The input name should be a valid variable name, without spaces. An input type an
   <data name="InvalidInputSymbolWarningTitle" xml:space="preserve">
     <value>Custom Node Contains Invalid Inputs and Cannot Be Saved.</value>
   </data>
+  <data name="PythonTemplateAppData" xml:space="preserve">
+    <value>Python template loaded from AppData</value>
+  </data>
+  <data name="PythonTemplateDefaultFile" xml:space="preserve">
+    <value>Python template set to default.</value>
+  </data>
+  <data name="PythonTemplateDefinedByHost" xml:space="preserve">
+    <value>Python template set by host integrator</value>
+  </data>
+  <data name="PythonTemplateUserFile" xml:space="preserve">
+    <value>Python template loaded from DynamoSettings.xml path</value>
+  </data>
 </root>

src/DynamoCore/Properties/Resources.resx

@@ -649,14 +649,14 @@ value : bool = false</value>
   <data name="NoneString" xml:space="preserve">
     <value>none</value>
   </data>
-  <data name="PythonTemplateInvalid" xml:space="preserve">
-    <value>Python template : no valid template found.</value>
+  <data name="PythonTemplateAppData" xml:space="preserve">
+    <value>Python template loaded from AppData</value>
   </data>
   <data name="PythonTemplateDefaultFile" xml:space="preserve">
-    <value>Python template set to default file</value>
+    <value>Python template set to default.</value>
   </data>
   <data name="PythonTemplateUserFile" xml:space="preserve">
-    <value>Python template set to user file</value>
+    <value>Python template loaded from DynamoSettings.xml path</value>
   </data>
   <data name="DefaultHomeWorkspaceName" xml:space="preserve">
     <value>Home</value>
@@ -697,4 +697,7 @@ The input name should be a valid variable name, without spaces. An input type an
   <data name="InvalidInputSymbolWarningTitle" xml:space="preserve">
     <value>Custom Node Contains Invalid Inputs and Cannot Be Saved.</value>
   </data>
+  <data name="PythonTemplateDefinedByHost" xml:space="preserve">
+    <value>Python template set by host integrator</value>
+  </data>
 </root>

test/DynamoCoreTests/Settings.cs

@@ -1,9 +1,8 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Text;
 using Dynamo.Configuration;
+using Dynamo.Models;
 using NUnit.Framework;
 
 namespace Dynamo.Tests
@@ -55,6 +54,36 @@ public void LoadInvalidPythonTemplateFromSetting()
             Assert.AreEqual(settings.PythonTemplateFilePath, pyFile);
         }
 
+        [Test]
+        public void SetPythonTemplateFromConfigWithValidPath()
+        {
+            var templatePath = Path.Combine(SettingDirectory, "PythonTemplate-initial.py");
+
+            var config = new DynamoModel.DefaultStartConfiguration()
+            {
+                PythonTemplatePath = templatePath
+            };
+
+            var model = DynamoModel.Start(config);
+
+            Assert.AreEqual(model.PreferenceSettings.PythonTemplateFilePath, templatePath);
+        }
+
+        [Test]
+        public void SetPythonTemplateFromConfigWithInvalidPath()
+        {
+            var templatePath = Path.Combine(@"C:\Users\SomeDynamoUser\Desktop", "PythonTemplate-initial.py");
+
+            var config = new DynamoModel.DefaultStartConfiguration()
+            {
+                PythonTemplatePath = templatePath
+            };
+
+            var model = DynamoModel.Start(config);
+
+            Assert.AreEqual(model.PreferenceSettings.PythonTemplateFilePath, string.Empty);
+        }
+
     }
 
 }