Refactor variable handling in storage driver logic

Refactored `StorageDriverContext` to include `Variable` and updated its usage across relevant methods to ensure context accuracy. Enhanced `ObjectConverter` to support conditional deserialization of JSON objects. Adjusted `WorkflowInstanceStorageDriver` to utilize improved variable resolution with new conversion options.

src/modules/Elsa.Expressions/Helpers/ObjectConverter.cs

@@ -19,7 +19,7 @@ namespace Elsa.Expressions.Helpers;
 /// <summary>
 /// Provides options to the conversion method.
 /// </summary>
-public record ObjectConverterOptions(JsonSerializerOptions? SerializerOptions = default, IWellKnownTypeRegistry? WellKnownTypeRegistry = default);
+public record ObjectConverterOptions(JsonSerializerOptions? SerializerOptions = null, IWellKnownTypeRegistry? WellKnownTypeRegistry = null, bool DeserializeJsonObjectToObject = false);
 
 /// <summary>
 /// A helper that attempts many strategies to try and convert the source value into the destination type. 
@@ -77,7 +77,7 @@ public static class ObjectConverter
     public static object? ConvertTo(this object? value, Type targetType, ObjectConverterOptions? converterOptions = null)
     {
         if (value == null)
-            return default!;
+            return null;
 
         var sourceType = value.GetType();
 
@@ -104,7 +104,7 @@ public static class ObjectConverter
             return underlyingTargetType switch
             {
                 { } t when t == typeof(string) => jsonNode.ToString(),
-                { } t when t != typeof(object) => jsonNode.Deserialize(targetType, serializerOptions),
+                { } t when t != typeof(object) || converterOptions?.DeserializeJsonObjectToObject == true => jsonNode.Deserialize(targetType, serializerOptions),
                 _ => jsonNode
             };
         }

src/modules/Elsa.Workflows.Core/Contexts/StorageDriverContext.cs

@@ -1,6 +1,8 @@
+using Elsa.Workflows.Memory;
+
 namespace Elsa.Workflows;
 
 /// <summary>
 /// Provides context for storage drivers.
 /// </summary>
-public record StorageDriverContext(IExecutionContext ExecutionContext, CancellationToken CancellationToken);
+public record StorageDriverContext(IExecutionContext ExecutionContext, Variable Variable, CancellationToken CancellationToken);

src/modules/Elsa.Workflows.Core/Services/VariablePersistenceManager.cs

@@ -22,7 +22,7 @@ public class VariablePersistenceManager(IStorageDriverManager storageDriverManag
             foreach (var variable in variables)
             {
                 context.ExpressionExecutionContext.Memory.Declare(variable);
-                var storageDriverContext = new StorageDriverContext(context, cancellationToken);
+                var storageDriverContext = new StorageDriverContext(context, variable, cancellationToken);
                 var register = context.ExpressionExecutionContext.Memory;
                 var block = EnsureBlock(register, variable);
                 var metadata = (VariableBlockMetadata)block.Metadata!;
@@ -65,7 +65,6 @@ public class VariablePersistenceManager(IStorageDriverManager storageDriverManag
         foreach (var context in contexts)
         {
             var variables = GetLocalVariables(context).ToList();
-            var storageDriverContext = new StorageDriverContext(context, cancellationToken);
 
             foreach (var variable in variables)
             {
@@ -78,6 +77,7 @@ public class VariablePersistenceManager(IStorageDriverManager storageDriverManag
 
                 var id = GetStateId(variable);
                 var value = block.Value;
+                var storageDriverContext = new StorageDriverContext(context, variable, cancellationToken);
 
                 if (value == null)
                     await driver.DeleteAsync(id, storageDriverContext);
@@ -93,7 +93,6 @@ public class VariablePersistenceManager(IStorageDriverManager storageDriverManag
         var register = context.ExpressionExecutionContext.Memory;
         var variableList = GetLocalVariables(context).ToList();
         var cancellationToken = context.CancellationToken;
-        var storageDriverContext = new StorageDriverContext(context, cancellationToken);
 
         foreach (var variable in variableList)
         {
@@ -107,6 +106,7 @@ public class VariablePersistenceManager(IStorageDriverManager storageDriverManag
                 continue;
 
             var id = GetStateId(variable);
+            var storageDriverContext = new StorageDriverContext(context, variable, cancellationToken);
             await driver.DeleteAsync(id, storageDriverContext);
             register.Blocks.Remove(variable.Id);
         }

src/modules/Elsa.Workflows.Core/VariableStorageDrivers/WorkflowInstanceStorageDriver.cs

@@ -1,6 +1,7 @@
 using System.ComponentModel.DataAnnotations;
 using System.Text.Json;
 using System.Text.Json.Nodes;
+using Elsa.Expressions.Helpers;
 using Elsa.Extensions;
 using JetBrains.Annotations;
 
@@ -11,7 +12,7 @@ namespace Elsa.Workflows;
 /// </summary>
 [Display(Name = "Workflow Instance")]
 [UsedImplicitly]
-public class WorkflowInstanceStorageDriver : IStorageDriver
+public class WorkflowInstanceStorageDriver(IPayloadSerializer payloadSerializer) : IStorageDriver
 {
     /// <summary>
     /// The key used to store the variables in the workflow state.
@@ -39,7 +40,15 @@ public class WorkflowInstanceStorageDriver : IStorageDriver
     {
         var dictionary = GetVariablesDictionary(context);
         var node = dictionary.GetValueOrDefault(id);
-        return new(node);
+        var variable = context.Variable;
+        var variableType = variable.GetVariableType();
+        var options = new ObjectConverterOptions
+        {
+            DeserializeJsonObjectToObject = true,
+            SerializerOptions = payloadSerializer.GetOptions()  
+        };
+        var parsedValue = node.ConvertTo(variableType, options);
+        return new (parsedValue);
     }
 
     /// <inheritdoc />