Dynamic Values

In the previous chapter's "User Lifecycle" example, we briefly mentioned using {{$randomUserName}} to verify user registration. This simple trick is actually part of a powerful feature called Dynamic Values.

When you pass data between steps, you're using real data. But often, you need fake but realistic data to make your tests robust and repeatable.

To solve this, we use Dynamic Values.

What are Dynamic Values?

Dynamic values are special variables built into Apidog (similar to "Faker" libraries) that generate random data every time the request is sent.

They follow the syntax {{$variableName}}.

Why use them?

Avoid Collisions: Never get "Duplicate Key" errors.

Realism: Test with different names, emails, and numbers every time.

Convenience: No need to manually type "test user 1", "test user 2".

Common Dynamic Variables

Here are the most useful ones for everyday testing:

Identifiers

{{$guid}}: A unique UUID (e.g., d4f5-a1b2-...). Perfect for Request IDs or Trace IDs.

{{$timestamp}}: Current Unix timestamp (e.g., 1678886472).

Personal Data

{{$randomUserName}}: A random username (e.g., brave_lion).

{{$randomEmail}}: A random email (e.g., example@xyz.com).

{{$randomPhoneNumber}}: A random phone number.

Numbers & Strings

{{$randomInt}}: A random integer between 0 and 1000.

{{$randomString}}: A random string of text.

Tip: Apidog provides hundreds of these. Just type {{$ in any value field, and the autocomplete list will appear. Or click the Magic Wand icon to browse the full list.

Real Case: Random User Registration

Let's fix our "User Registration" test so it never fails with a duplicate email error.

Old Body (Static):

{
  "username": "testuser",
  "email": "test@example.com",
  "password": "Password123"
}

New Body (Dynamic):

{
  "username": "{{$randomUserName}}",
  "email": "{{$randomUserName}}@example.com",
  "password": "Password123"
}

Now, every time you run this test, Apidog generates a fresh user:

Run 1: "username": "blue_sky"

Run 2: "username": "fast_tiger"

Using Dynamic Values in Parameters

You can also use them in query parameters.

GET /items?cacheBuster={{$timestamp}}

This ensures the server never returns a cached response because the URL is always unique.

Key Takeaways

Use Dynamic Values to prevent data collision and "Duplicate Key" errors.

Master common variables like {{$timestamp}}, {{$guid}}, and {{$randomUserName}}.

Apply dynamic data to make your tests robust and repeatable without manual cleanup.

What's Next

Now that we have data flowing between requests (Integration) and unique data for every run (Dynamic Values), we need to ensure the API is actually returning the correct results.

In the next chapter, we'll dive into Assertions and Validations.

Continue with → Assertions and Validations

What are Dynamic Values?#

Why use them?#

Common Dynamic Variables#

Identifiers#

Personal Data#

Numbers & Strings#

Real Case: Random User Registration#

Using Dynamic Values in Parameters#

Key Takeaways#

What's Next#