Dynamic Variables

Overview

Dynamic variables allow you to generate random, unique data on-the-fly without writing scripts. Perfect for load testing, creating test data, and avoiding hardcoded values.

Available Dynamic Variables

Request Man provides 9 built-in dynamic variables. Simply use them anywhere in your requests:

How to Use Dynamic Variables

In URL

GET https://api.example.com/users/{{$guid}}
GET https://api.example.com/data?timestamp={{$timestamp}}

In Headers

X-Request-ID: {{$guid}}
X-Timestamp: {{$timestamp}}
X-Trace-ID: {{$randomUUID}}

In JSON Body

{
  "id": "{{$guid}}",
  "timestamp": {{$timestamp}},
  "email": "{{$randomEmail}}",
  "age": {{$randomInt}},
  "active": {{$randomBoolean}},
  "ip_address": "{{$randomIP}}",
  "session_id": "{{$randomAlphaNumeric}}"
}

In Query Parameters

page={{$randomInt}}
id={{$guid}}
timestamp={{$timestamp}}

Practical Examples

Example 1: User Registration Testing

Create unique users without manually changing email addresses:

POST https://api.example.com/users
Content-Type: application/json

{
  "id": "{{$guid}}",
  "email": "{{$randomEmail}}",
  "username": "user_{{$randomAlphaNumeric}}",
  "created_at": {{$timestamp}},
  "is_active": {{$randomBoolean}},
  "ip_address": "{{$randomIP}}"
}

Example 2: Order Creation (Load Testing)

Generate unique orders for load testing:

POST https://api.example.com/orders
Content-Type: application/json

{
  "order_id": "{{$guid}}",
  "transaction_id": "{{$randomUUID}}",
  "customer_id": {{$randomInt}},
  "amount": {{$randomInt}},
  "timestamp": {{$timestamp}},
  "created_at": "{{$isoTimestamp}}",
  "confirmed": {{$randomBoolean}}
}

Example 3: API Request Tracking

Add unique identifiers to track requests:

GET https://api.example.com/data
X-Request-ID: {{$guid}}
X-Timestamp: {{$timestamp}}
X-Trace-ID: {{$randomUUID}}
X-Client-IP: {{$randomIP}}

Example 4: A/B Testing with Random Flags

Randomly enable/disable features:

POST https://api.example.com/feature-flags
Content-Type: application/json

{
  "user_id": "{{$guid}}",
  "new_ui_enabled": {{$randomBoolean}},
  "beta_features": {{$randomBoolean}},
  "experimental_mode": {{$randomBoolean}},
  "timestamp": {{$timestamp}}
}

Uniqueness & Freshness

Fresh Generation Every Time

Dynamic variables generate new values for each request:

{"id": "aaaa-bbbb-cccc-dddd", "email": "user_abc@example.com"}

{"id": "1111-2222-3333-4444", "email": "user_xyz@example.com"}

{"id": "9999-8888-7777-6666", "email": "user_def@example.com"}

Multiple Variables in Same Request

Each occurrence generates a unique value:

{
  "order_id": "{{$guid}}",          // aaaa-bbbb-cccc-dddd
  "transaction_id": "{{$guid}}",    // 1111-2222-3333-4444
  "session_id": "{{$guid}}"         // 9999-8888-7777-6666
}

All three GUIDs will be different!

Load Testing with Dynamic Variables

Collection Runner Integration

Use dynamic variables with Collection Runner for powerful load testing:

POST https://api.example.com/orders
{
  "order_id": "{{$guid}}",
  "user_id": {{$randomInt}},
  "timestamp": {{$timestamp}}
}

Combining with Other Variables

Mix dynamic variables with environment and collection variables:

Example: Multi-Environment Testing

POST {{baseUrl}}/api/users
Content-Type: application/json
Authorization: Bearer {{authToken}}

{
  "id": "{{$guid}}",
  "email": "{{$randomEmail}}",
  "timestamp": {{$timestamp}},
  "environment": "{{env_name}}"
}

Testing Generated Values

Use test scripts to validate dynamic variable output:

UUID Format Validation

// Test that GUID is valid UUID format
rm.test("GUID is valid UUID", function () {
    const jsonData = rm.response.json();
    const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
    rm.expect(jsonData.id).to.match(uuidRegex);
});

Timestamp Validation

// Test that timestamp is recent (within last 5 seconds)
rm.test("Timestamp is recent", function () {
    const jsonData = rm.response.json();
    const now = Math.floor(Date.now() / 1000);
    rm.expect(jsonData.timestamp).to.be.closeTo(now, 5);
});

Email Format Validation

// Test that email is valid format
rm.test("Email is valid", function () {
    const jsonData = rm.response.json();
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    rm.expect(jsonData.email).to.match(emailRegex);
});

Boolean Type Validation

// Test that boolean is actual boolean type
rm.test("Active is boolean", function () {
    const jsonData = rm.response.json();
    rm.expect(jsonData.active).to.be.a('boolean');
});

Dynamic Variables vs. Scripts

When to Use Dynamic Variables

• Quick testing with random data
• Load testing with unique IDs
• Creating test users/orders/records
• Adding timestamps to requests
• Generating request tracking IDs

When to Use Scripts Instead

• Custom data format requirements
• Complex calculations or transformations
• Conditional logic
• Calling external APIs for data
• Cryptographic operations

Tips & Best Practices