From e23cf08f818994c5bb31e58d0ecd8c6b218ffa7c Mon Sep 17 00:00:00 2001
From: Sipke Schoorstra <sipkeschoorstra@outlook.com>
Date: Sat, 5 Dec 2020 11:15:27 +0100
Subject: [PATCH] Allow access to parent activity state from child activity

---
 src/core/Elsa.Abstractions/Models/WorkflowInstance.cs         | 2 ++
 src/core/Elsa.Abstractions/Services/CompositeActivity.cs      | 4 ++++
 .../Services/Models/ActivityBlueprintWrapper.cs               | 4 ++--
 .../Services/Models/ActivityExecutionContext.cs               | 4 ++++
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/core/Elsa.Abstractions/Models/WorkflowInstance.cs b/src/core/Elsa.Abstractions/Models/WorkflowInstance.cs
index d1a3834407..6813d73d3 100644
--- a/src/core/Elsa.Abstractions/Models/WorkflowInstance.cs
+++ b/src/core/Elsa.Abstractions/Models/WorkflowInstance.cs
@@ -15,6 +15,7 @@ namespace Elsa.Models
             ExecutionLog = new List<ExecutionLogEntry>();
             ScheduledActivities = new Stack<ScheduledActivity>();
             PostScheduledActivities = new Stack<ScheduledActivity>();
+            ParentActivities = new Stack<string>();
         }
 
         public int Id { get; set; }
@@ -40,5 +41,6 @@ namespace Elsa.Models
         public WorkflowFault? Fault { get; set; }
         public Stack<ScheduledActivity> ScheduledActivities { get; set; }
         public Stack<ScheduledActivity> PostScheduledActivities { get; set; }
+        public Stack<string> ParentActivities { get; set; }
     }
 }
\ No newline at end of file
diff --git a/src/core/Elsa.Abstractions/Services/CompositeActivity.cs b/src/core/Elsa.Abstractions/Services/CompositeActivity.cs
index 5043f305e..5b436fd43 100644
--- a/src/core/Elsa.Abstractions/Services/CompositeActivity.cs
+++ b/src/core/Elsa.Abstractions/Services/CompositeActivity.cs
@@ -20,10 +20,14 @@ namespace Elsa.Services
         protected override IActivityExecutionResult OnExecute(ActivityExecutionContext context)
         {
             if (IsScheduled)
+            {
+                context.WorkflowExecutionContext.WorkflowInstance.ParentActivities.Pop();
                 return Complete(context);
+            }
             
             var compositeActivityBlueprint = (ICompositeActivityBlueprint)context.ActivityBlueprint;
             var startActivities = compositeActivityBlueprint.GetStartActivities().Select(x => x.Id).ToList();
+            context.WorkflowExecutionContext.WorkflowInstance.ParentActivities.Push(Id);
             context.WorkflowExecutionContext.PostScheduleActivity(Id);
             IsScheduled = true;
             return Schedule(startActivities, context.Input);
diff --git a/src/core/Elsa.Abstractions/Services/Models/ActivityBlueprintWrapper.cs b/src/core/Elsa.Abstractions/Services/Models/ActivityBlueprintWrapper.cs
index 0e9c71c8d..62ce289d6 100644
--- a/src/core/Elsa.Abstractions/Services/Models/ActivityBlueprintWrapper.cs
+++ b/src/core/Elsa.Abstractions/Services/Models/ActivityBlueprintWrapper.cs
@@ -30,12 +30,12 @@ namespace Elsa.Services.Models
             var workflowBlueprint = ActivityExecutionContext.WorkflowExecutionContext.WorkflowBlueprint;
             var activityId = ActivityExecutionContext.ActivityBlueprint.Id;
 
-            // Computed property setters that depend on actual workflow state might fault, since we are using a fake activity execution context.
+            // Computed property setters that depend on actual workflow state might fault, since we might be using a fake activity execution context.
             try
             {
                 return await workflowBlueprint.GetActivityPropertyValue(activityId, propertyExpression, ActivityExecutionContext, cancellationToken);
             }
-            catch (Exception e)
+            catch (Exception)
             {
                 return default;
             }
diff --git a/src/core/Elsa.Abstractions/Services/Models/ActivityExecutionContext.cs b/src/core/Elsa.Abstractions/Services/Models/ActivityExecutionContext.cs
index e014d73aa..df0afe86f 100644
--- a/src/core/Elsa.Abstractions/Services/Models/ActivityExecutionContext.cs
+++ b/src/core/Elsa.Abstractions/Services/Models/ActivityExecutionContext.cs
@@ -42,6 +42,10 @@ namespace Elsa.Services.Models
             set => ActivityInstance.Output = value;
         }
 
+        public ActivityBlueprintWrapper<T> Parent<T>() where T : IActivity => new(new ActivityExecutionContext(ServiceScope, WorkflowExecutionContext,
+            WorkflowExecutionContext.GetActivityBlueprintById(WorkflowExecutionContext.WorkflowInstance.ParentActivities.Peek()),
+            null, CancellationToken));
+
         public void SetVariable(string name, object? value) => WorkflowExecutionContext.SetVariable(name, value);
         public object? GetVariable(string name) => WorkflowExecutionContext.GetVariable(name);
         public T GetVariable<T>(string name) => WorkflowExecutionContext.GetVariable<T>(name);