Variables

Variables are how data flows through your workflows. They allow nodes to pass information to each other, reference trigger data, and access environment configuration.

Variable Syntax

Use double curly braces to reference variables:

{{variable_name}}
{{node_name.output.field}}
{{trigger.body.message}}

Variable Sources

Trigger Variables

Data from the event that started the workflow:

{{trigger.body}}         // Request body (webhooks)
{{trigger.headers}}      // HTTP headers
{{trigger.params}}       // URL parameters
{{trigger.query}}        // Query string parameters
{{trigger.method}}       // HTTP method

Node Output Variables

Results from previous nodes:

{{node_name.output}}              // Complete output
{{node_name.output.field}}        // Specific field
{{node_name.output.nested.field}} // Nested access
{{node_name.output[0]}}           // Array index
{{node_name.output.items[0].name}} // Combined access

Environment Variables

Secure configuration values:

{{env.API_KEY}}
{{env.DATABASE_URL}}
{{env.SECRET_TOKEN}}

Loop Variables

Inside loop nodes:

{{loop.item}}        // Current item
{{loop.index}}       // Current index (0-based)
{{loop.length}}      // Total items
{{loop.isFirst}}     // Is first iteration
{{loop.isLast}}      // Is last iteration

Parallel Variables

Inside parallel executions:

{{parallel.index}}   // Parallel execution index
{{parallel.total}}   // Total parallel executions
{{parallel.batchId}} // Current batch ID

Shared Memory

Workflow-level shared state:

{{shared.key}}       // Access shared memory value

Expression Support

Variables support JavaScript expressions for dynamic values.

Logical Operators

{{value || "default"}}           // OR with fallback
{{condition && "yes"}}           // AND with value
{{!flag}}                        // NOT operator

Comparison Operators

{{count == 5}}                   // Equality
{{status != "error"}}            // Inequality
{{total > 100}}                  // Greater than
{{price <= 50}}                  // Less than or equal

Ternary Operator

{{status == "active" ? "Yes" : "No"}}
{{items.length > 0 ? items[0] : null}}

Arithmetic

{{price * quantity}}
{{total + tax}}
{{(price * 1.1).toFixed(2)}}

String Operations

{{name.toUpperCase()}}
{{email.toLowerCase()}}
{{message.trim()}}
{{`Hello, ${name}!`}}

Array Operations

{{items.length}}
{{items.join(", ")}}
{{items.map(i => i.name)}}
{{items.filter(i => i.active)}}
{{items.find(i => i.id == targetId)}}

Object Operations

{{Object.keys(data)}}
{{Object.values(config)}}
{{JSON.stringify(result)}}

Resolution Hierarchy

When resolving a variable, FlowMaestro checks sources in this order:

1. Node outputs — Results from workflow nodes
2. Loop context — If inside a loop
3. Parallel context — If in parallel execution
4. Shared memory — Workflow-level storage
5. Trigger data — Input that started the workflow
6. Environment — Workspace environment variables
7. Globals — System-level constants

Null and Undefined Handling

Handle missing values gracefully:

{{user.name || "Anonymous"}}              // Default if null/undefined
{{user?.profile?.avatar}}                 // Optional chaining
{{data ?? "fallback"}}                    // Nullish coalescing

Type Coercion

Variables maintain their types through the workflow:

Type	Examples
String	"hello", {{name}}
Number	42, {{count}}
Boolean	true, {{isActive}}
Array	[1,2,3], {{items}}
Object	{key: "value"}, {{data}}
Null	null, {{missing}}

Explicit Type Conversion

{{Number(stringValue)}}           // To number
{{String(numericValue)}}          // To string
{{Boolean(value)}}                // To boolean
{{JSON.parse(jsonString)}}        // Parse JSON

Common Patterns

Conditional Default Values

{{user.nickname || user.firstName || "User"}}

Safe Property Access

{{order?.customer?.email || "no-email"}}

Array Processing

// Get names from array of objects
{{users.map(u => u.name).join(", ")}}

// Filter and count
{{orders.filter(o => o.status == "pending").length}}

// Find specific item
{{products.find(p => p.sku == targetSku)}}

Template Strings

{{`Order #${order.id} for ${customer.name}`}}
{{`Total: $${(price * quantity).toFixed(2)}`}}

Date Formatting

{{new Date().toISOString()}}
{{new Date(timestamp).toLocaleDateString()}}

Using Variables in Nodes

In Text Fields

Simply insert the variable:

Hello, {{user.name}}! Your order #{{order.id}} is ready.

In JSON Fields

Use within JSON structures:

{
    "to": "{{customer.email}}",
    "subject": "Order {{order.id}} Confirmed",
    "body": "{{email_body}}"
}

In Code Nodes

Access via the inputs object:

const userName = inputs.user.name;
const orderTotal = inputs.order.total;

return {
    greeting: `Hello, ${userName}!`,
    formattedTotal: `$${orderTotal.toFixed(2)}`
};

Variable Explorer

Use the Variable Explorer to browse available variables:

1. Click in any variable field
2. Press Cmd/Ctrl + Space
3. Browse and select from available variables

Debugging Variables

Preview Values

In the workflow editor, hover over a variable to see its current value in test mode.

Execution Logs

View resolved variables in execution details:

{
    "nodeId": "llm_1",
    "resolvedInputs": {
        "prompt": "Summarize this: Lorem ipsum...",
        "temperature": 0.7
    }
}

Best Practices

Use Descriptive Names

// Good
outputVariable: "customer_order_details";

// Avoid
outputVariable: "data";

Handle Missing Data

// Always provide fallbacks for optional data
{{user.preferences?.theme || "light"}}

Keep Expressions Simple

// For complex logic, use a Transform node instead of inline expressions

Validate Before Use

Use conditional nodes to check for required data before processing.

Document Variables

Add descriptions to output variables:

{
  outputVariable: "processed_results",
  description: "Array of validated customer records"
}