Variables & Dynamic Functions

Use variables and dynamic functions to make your requests dynamic, generate test data, and create powerful API workflows.

Overview

Echolon provides a powerful variable system that goes beyond simple environment variables. You can use the {{expression}} syntax to:

Reference environment variables
Generate random data (names, emails, numbers, etc.)
Create unique identifiers (UUIDs)
Generate timestamps in various formats
Encode/decode values (Base64, URL encoding)
Create hashes (MD5, SHA-256, etc.)
Access context information (workspace, collection IDs)

Variables and functions can be used in URLs, query parameters, headers, request bodies, and scripts.

Variable Types

Environment variables are defined at different scopes with the following priority (highest to lowest):

Collection Environment Variables: Scoped to a collection's environment (e.g., "Production", "Staging")
Collection Variables: Scoped to a specific collection
Global Environment Variables: Available everywhere in the active global environment

If a variable name exists in multiple scopes, the higher-priority scope takes precedence. This allows you to override global variables with collection-specific values.

Syntax

Reference variables using double curly braces:

{{baseUrl}}/users/{{userId}}

For functions with parameters, use named arguments:

{{random.range(min=1, max=100)}}
{{timestamp.format(format="YYYY-MM-DD")}}

Functions without parameters can be called directly:

{{uuid.v4}}
{{timestamp.iso8601}}

Dynamic Functions

Dynamic functions generate values at request time. They are organized into categories and can be discovered by typing {{ in any input field.

Random Functions

Generate random data for testing and mock scenarios.

Function	Description	Example Output
`random.range(min, max, decimals?)`	Random number between min and max	`42`
`random.integer(min?, max?)`	Random integer	`847`
`random.float(min?, max?, decimals?)`	Random floating-point number	`0.73`
`random.boolean`	Random true/false	`true`
`random.firstName`	Random first name	`Emma`
`random.lastName`	Random last name	`Johnson`
`random.fullName`	Random full name	`James Wilson`
`random.email(domain?)`	Random email address	`john.doe42@example.com`
`random.phone(format?)`	Random phone number	`(555) 123-4567`
`random.username`	Random username	`cool_ninja42`
`random.password(length?)`	Random password	`xK9#mP2@nL5$`
`random.alphanumeric(length?)`	Random alphanumeric string	`a7Bk9mNp`
`random.word`	Random word	`ocean`
`random.sentence(words?)`	Random sentence	`Quick brown fox jumps.`
`random.paragraph(sentences?)`	Random paragraph	`Lorem ipsum dolor sit amet...`
`random.company`	Random company name	`Tech Solutions`
`random.address`	Random street address	`123 Main Street`
`random.city`	Random city name	`Seattle`
`random.country`	Random country name	`Canada`
`random.hexColor`	Random hex color	`#3a7bd5`
`random.ipv4`	Random IPv4 address	`192.168.1.42`
`random.ipv6`	Random IPv6 address	`2001:0db8:85a3:...`
`random.url`	Random URL	`https://example.com/api`
`random.date(start?, end?)`	Random date	`2024-06-15`
`random.creditCard`	Random test card number	`4532 1234 5678 9012`

UUID Functions

Generate universally unique identifiers.

Function	Description	Example Output
`uuid.v1`	Time-based UUID (v1)	`6ba7b810-9dad-11d1-80b4-...`
`uuid.v4`	Random UUID (v4)	`550e8400-e29b-41d4-a716-...`

Hash Functions

Generate cryptographic hashes. If no input is provided, a random string is hashed.

Function	Description	Example Output
`hash.md5(input?)`	MD5 hash	`d41d8cd98f00b204e980...`
`hash.sha1(input?)`	SHA-1 hash	`da39a3ee5e6b4b0d3255...`
`hash.sha256(input?)`	SHA-256 hash	`e3b0c44298fc1c149afb...`
`hash.sha512(input?)`	SHA-512 hash	`cf83e1357eefb8bdf154...`

Timestamp Functions

Generate timestamps in various formats.

Function	Description	Example Output
`timestamp.now`	Current timestamp (ms)	`1704067200000`
`timestamp.unix`	Unix timestamp (seconds)	`1704067200`
`timestamp.unixMillis`	Unix timestamp (milliseconds)	`1704067200000`
`timestamp.iso8601`	ISO 8601 format	`2024-01-01T00:00:00.000Z`
`timestamp.date`	Date only (YYYY-MM-DD)	`2024-01-01`
`timestamp.time`	Time only (HH:mm:ss)	`14:30:45`
`timestamp.format(format?)`	Custom format	`2024-01-01 14:30:45`

Format tokens for timestamp.format:

YYYY - 4-digit year
MM - 2-digit month (01-12)
DD - 2-digit day (01-31)
HH - 2-digit hour (00-23)
mm - 2-digit minutes (00-59)
ss - 2-digit seconds (00-59)
SSS - 3-digit milliseconds

Encoding Functions

Encode and decode strings.

Function	Description	Example
`base64.encode(value)`	Base64 encode	`hello` → `aGVsbG8=`
`base64.decode(value)`	Base64 decode	`aGVsbG8=` → `hello`
`url.encode(value)`	URL encode	`hello world` → `hello%20world`
`url.decode(value)`	URL decode	`hello%20world` → `hello world`

JSON Functions

Manipulate JSON data.

Function	Description
`json.minify(json)`	Remove whitespace from JSON
`json.escape(value)`	Escape string for JSON
`json.stringify(value)`	Convert to JSON string

Context Functions

Access information about the current context.

Function	Description
`ctx.workspace`	Current workspace ID
`ctx.environment`	Current environment ID
`ctx.collection`	Current collection ID
`ctx.request`	Current request ID

When you click on a function in the autocomplete dropdown, a configuration modal opens where you can:

Set parameter values using input fields
See a live preview of the generated value
Regenerate the preview to see different random values
Insert the configured function into your request

Double-clicking on an existing function in a field will reopen the configuration modal, allowing you to modify its parameters.

Use Cases

1. Generate Unique User Data for Testing

POST /api/users
Content-Type: application/json

{
  "id": "{{uuid.v4}}",
  "firstName": "{{random.firstName}}",
  "lastName": "{{random.lastName}}",
  "email": "{{random.email}}",
  "createdAt": "{{timestamp.iso8601}}"
}

2. Create Authenticated Requests with Timestamps

GET /api/data
Authorization: Bearer {{apiToken}}
X-Request-ID: {{uuid.v4}}
X-Timestamp: {{timestamp.unix}}

3. Generate Random Test Data

POST /api/orders
Content-Type: application/json

{
  "orderId": "ORD-{{random.alphanumeric(length=8)}}",
  "amount": {{random.range(min=10, max=500, decimals=2)}},
  "items": {{random.integer(min=1, max=10)}},
  "shippingAddress": "{{random.address}}, {{random.city}}"
}

4. URL-Encoded Query Parameters

GET /api/search?q={{url.encode(value="hello world")}}&timestamp={{timestamp.unix}}

5. Generate API Signatures

POST /api/webhook
X-Signature: {{hash.sha256(input="{{secretKey}}{{timestamp.unix}}")}}
X-Timestamp: {{timestamp.unix}}

6. Base64-Encoded Credentials

Authorization: Basic {{base64.encode(value="{{username}}:{{password}}")}}