Managing State & Variables

Workflows maintain state across asynchronous pauses using Context Variables.

Defining Variables

Before variables can be used in a workflow, they must be defined in the Variables array of the WorkflowDefinition.

"Variables": [
  { "Name": "ApprovalResult", "Type": "String" },
  { "Name": "DiscountApplied", "Type": "Decimal" }
]

Dynamic LINQ Expressions

When configuring nodes, you often need to evaluate conditions or assign values. Struktural uses Dynamic LINQ for runtime evaluation.

• Accessing Entity Data: Prefix the field name with @Entity. (e.g., @Entity.TotalAmount).
• Accessing Variables: Prefix the variable name with @Variables. (e.g., @Variables.ApprovalResult).

String Literal Escaping (CRITICAL)

Because expressions are evaluated inside JSON configuration strings, C# string literals MUST be escaped with double quotes. Single quotes (') are generally NOT supported for string literals in the expression parser.

• CORRECT: "Condition": "@Entity.Status == \"Approved\""
• WRONG: "Condition": "@Entity.Status == 'Approved'"

Modifying State (ExpressionTransform Node)

To perform mathematical calculations or logic and store the result in a variable, use the ExpressionTransform node.

{
  "Id": "exp_1", 
  "Type": "ExpressionTransform", 
  "NextNodeId": "node_2", 
  "Configuration": {
    "TargetVariable": "Variables.DiscountApplied", 
    "Expression": "@Entity.Amount * 0.15"
  }
}

Text Templating

Certain nodes that output human-readable text (like SendEmail or the TaskTitle in WaitForUserAction) support Handlebars-style token replacement instead of raw LINQ. In these fields, use {{token}}:

• "Subject": "New order received from {{Entity.CustomerName}}"
• "Body": "The workflow resulted in: {{Variables.ApprovalResult}}"