From 3083a400d8fa1ae210d170cc0ad11d7a249a72e4 Mon Sep 17 00:00:00 2001
From: jdevillard <djay93@hotmail.com>
Date: Fri, 30 Aug 2024 12:01:44 +0200
Subject: [PATCH] Add Variable available in dropdown when configuring a
 activity input (#5918)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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* Sample to provide a ExpressionDescriptorProvider

* fix variable accessor in VariableExpressionHandler

* remove Variable Expression to use default one

* Change the Variable Expression Provider to handle Variable Expression correctly

* need to check on UI Side and Server side is valid JSON is sent. For example, if a use change from a literal value to a Variable value, the value is sent to the API and result in an exception, we cannot handle invalid json  without using Try/Catch

---------

Co-authored-by: Jérémie DEVILLARD <jdevillard@users.noreply.github.com>
Co-authored-by: Sipke Schoorstra <sipkeschoorstra@outlook.com>
---
 .../Program.cs                                 | 12 +++++++-----
 .../DefaultExpressionDescriptorProvider.cs     | 18 ++++++++++++++----
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/samples/aspnet/Elsa.Samples.AspNet.CustomUIHandler/Program.cs b/samples/aspnet/Elsa.Samples.AspNet.CustomUIHandler/Program.cs
index ea1ed15dd..c53d22c15 100644
--- a/samples/aspnet/Elsa.Samples.AspNet.CustomUIHandler/Program.cs
+++ b/samples/aspnet/Elsa.Samples.AspNet.CustomUIHandler/Program.cs
@@ -1,3 +1,4 @@
+using Elsa.EntityFrameworkCore.Extensions;
 using Elsa.EntityFrameworkCore.Modules.Management;
 using Elsa.EntityFrameworkCore.Modules.Runtime;
 using Elsa.Extensions;
@@ -7,8 +8,8 @@ var builder = WebApplication.CreateBuilder(args);
 
 builder.Services.AddElsa(elsa =>
 {
-    elsa.UseWorkflowManagement(management => management.UseEntityFrameworkCore());
-    elsa.UseWorkflowRuntime(runtime => runtime.UseEntityFrameworkCore());
+    elsa.UseWorkflowManagement(management => management.UseEntityFrameworkCore(ef => ef.UseSqlite()));
+    elsa.UseWorkflowRuntime(runtime => runtime.UseEntityFrameworkCore(ef=>ef.UseSqlite()));
     
     elsa.UseWorkflowsApi();
     elsa.UseHttp();
@@ -26,12 +27,12 @@ builder.Services.AddElsa(elsa =>
     });
     
     elsa.UseDefaultAuthentication();
-    elsa.AddActivity<VehicleActivity>();
+    elsa.AddActivity<VehicleActivity>();
 });
 
 builder.Services.AddSingleton<VehicleUIHandler>();
 builder.Services.AddCors(cors => cors.AddDefaultPolicy(policy => policy.AllowAnyHeader().AllowAnyMethod().AllowAnyOrigin()));
-
+
 var app = builder.Build();
 
 // Configure the HTTP request pipeline.
@@ -41,4 +42,5 @@ app.UseAuthentication();
 app.UseAuthorization();
 app.UseWorkflowsApi();
 app.Map("/test",c=> c.UseWorkflows());
-app.Run();
\ No newline at end of file
+app.Run();
+
diff --git a/src/modules/Elsa.Workflows.Management/Providers/DefaultExpressionDescriptorProvider.cs b/src/modules/Elsa.Workflows.Management/Providers/DefaultExpressionDescriptorProvider.cs
index e85742a7c..67d1994f8 100644
--- a/src/modules/Elsa.Workflows.Management/Providers/DefaultExpressionDescriptorProvider.cs
+++ b/src/modules/Elsa.Workflows.Management/Providers/DefaultExpressionDescriptorProvider.cs
@@ -49,13 +49,23 @@ public class DefaultExpressionDescriptorProvider : IExpressionDescriptorProvider
         return CreateDescriptor<VariableExpressionHandler>(
             "Variable",
             "Variable",
-            isBrowsable: false,
+            isBrowsable: true,
             memoryBlockReferenceFactory: () => new Variable(),
             deserialize: context =>
             {
-                var valueElement = context.JsonElement.TryGetProperty("value", out var v) ? v : default;
-                var value = valueElement.Deserialize(context.MemoryBlockType, context.Options);
-                return new Expression("Variable", value);
+                var valueElement = context.JsonElement.TryGetProperty("value", out var v) ? v : default;
+                var valueString = valueElement.GetValue()?.ToString();
+                try
+                {
+                    var value = JsonSerializer.Deserialize(valueString, context.MemoryBlockType, context.Options);
+                    return new Expression("Variable", value);
+                }
+                catch (Exception)
+                {
+
+                    return new Expression("Variable", null);
+                }
+                
             }
         );
     }