Pre-request Scripts

Pre-request scripts execute before the HTTP request is sent, allowing you to modify the request, set variables, or perform setup logic.

Available Objects

In pre-request scripts, you have access to:

bru - Main Bruno API object
req - Request object
test - Test function (can run tests in pre-request scripts)
expect / assert - Chai assertion libraries
console - Logging functions

The res (response) object is not available in pre-request scripts since the request hasn’t been sent yet.

Request Object (req)

The req object represents the outgoing HTTP request.

Properties

string

The request URL

string

HTTP method (GET, POST, PUT, DELETE, etc.)

object

Request headers as key-value pairs

any

Request body (automatically parsed if JSON)

number

Request timeout in milliseconds

string

Name of the request

array

Path parameters array

array

Tags associated with the request

Methods

URL Methods

function

Returns the full request URL

const url = req.getUrl();
console.log('Sending request to:', url);

function

Sets the request URLParameters:

url (string) - The new URL

req.setUrl('https://api.example.com/v2/users');

function

Returns the host from the URL (including port)

const host = req.getHost();
// Returns: "api.example.com:443"

function

Returns the path portion of the URL (with path params interpolated)

const path = req.getPath();
// Returns: "/api/users/123"

function

Returns the query string without the leading ?

const query = req.getQueryString();
// Returns: "page=1&limit=10"

Header Methods

function

Gets a specific header valueParameters:

name (string) - Header name

const authHeader = req.getHeader('Authorization');

function

Sets a header valueParameters:

name (string) - Header name
value (string) - Header value

req.setHeader('Authorization', 'Bearer ' + token);
req.setHeader('Content-Type', 'application/json');

function

Removes a headerParameters:

name (string) - Header name

req.deleteHeader('X-Debug');

function

Returns all headers as an object

const headers = req.getHeaders();
console.log('All headers:', headers);

function

Replaces all headersParameters:

headers (object) - New headers object

req.setHeaders({
  'Authorization': 'Bearer token',
  'Content-Type': 'application/json'
});

function

Removes multiple headersParameters:

names (array) - Array of header names

req.deleteHeaders(['X-Debug', 'X-Test']);

Body Methods

function

Gets the request bodyParameters:

options.raw (boolean) - If true, returns raw string instead of parsed JSON

// Get parsed body (if JSON)
const body = req.getBody();

// Get raw body string
const rawBody = req.getBody({ raw: true });

function

Sets the request bodyParameters:

data (any) - Body data (object will be stringified if JSON content type)
options.raw (boolean) - If true, sets raw data without JSON processing

// Set JSON body (auto-stringified)
req.setBody({
  username: 'john',
  email: 'john@example.com'
});

// Set raw body
req.setBody('raw data', { raw: true });

Other Methods

function

Returns the HTTP method

const method = req.getMethod();
// Returns: "POST"

function

Sets the HTTP methodParameters:

method (string) - HTTP method (GET, POST, etc.)

req.setMethod('PUT');

function

Returns the request timeout in milliseconds

function

Sets the request timeoutParameters:

timeout (number) - Timeout in milliseconds

req.setTimeout(30000); // 30 seconds

function

Sets the maximum number of redirects to followParameters:

max (number) - Maximum redirects

req.setMaxRedirects(5);

function

Returns the authentication mode in useReturns: 'none', 'basic', 'bearer', 'oauth2', 'awsv4', 'digest', or 'wsse'

const authMode = req.getAuthMode();
if (authMode === 'bearer') {
  console.log('Using bearer authentication');
}

function

Returns the request name

function

Returns array of path parameters

const params = req.getPathParams();
// Returns: [{name: 'id', value: '123', type: 'path'}]

function

Returns array of request tags

function

Returns the execution mode (e.g., ‘cli’, ‘gui’)

function

Registers a callback to run if the request failsParameters:

callback (function) - Function to call on failure

req.onFail(() => {
  console.log('Request failed!');
  bru.setEnvVar('last_error', 'Request failed');
});

function

Disables automatic JSON parsing of the response body

// Keep response as raw string
req.disableParsingResponseJson();

Bruno Object (bru)

The bru object provides methods for managing variables, environment, and request flow. See the Post-response Scripts page for complete bru API reference, as all methods are available in both contexts. Key methods commonly used in pre-request scripts:

// Variables
bru.setVar('key', 'value');
const value = bru.getVar('key');

// Environment variables
bru.setEnvVar('api_token', token);
const token = bru.getEnvVar('api_token');

// Request flow control
bru.runner.skipRequest(); // Skip this request
bru.setNextRequest('request-name'); // Set next request to run

Common Patterns

Authentication

script:pre-request {
  // Basic Auth
  const username = bru.getEnvVar('username');
  const password = bru.getEnvVar('password');
  const encoded = require('btoa')(`${username}:${password}`);
  req.setHeader('Authorization', `Basic ${encoded}`);
  
  // Bearer Token
  const token = bru.getEnvVar('access_token');
  req.setHeader('Authorization', `Bearer ${token}`);
}

Dynamic Request Body

script:pre-request {
  const body = req.getBody();
  
  // Add timestamp
  body.timestamp = Date.now();
  
  // Add request ID
  body.requestId = bru.getVar('request_counter') || 1;
  bru.setVar('request_counter', body.requestId + 1);
  
  // Add signature
  const CryptoJS = require('crypto-js');
  const secret = bru.getEnvVar('api_secret');
  body.signature = CryptoJS.HmacSHA256(
    JSON.stringify(body), 
    secret
  ).toString();
  
  req.setBody(body);
}

Conditional Logic

script:pre-request {
  const env = bru.getEnvName();
  
  if (env === 'production') {
    // Use production endpoint
    req.setUrl('https://api.example.com/v1/users');
  } else {
    // Use staging endpoint
    req.setUrl('https://staging.example.com/v1/users');
  }
}

URL Manipulation

script:pre-request {
  // Get current URL
  const url = req.getUrl();
  
  // Parse and modify
  const urlObj = new URL(url);
  urlObj.searchParams.set('api_key', bru.getEnvVar('api_key'));
  urlObj.searchParams.set('timestamp', Date.now());
  
  // Update request
  req.setUrl(urlObj.toString());
}

Bru Language

Scripting API

CLI Reference

Pre-request Scripts

Available Objects

Request Object (req)

Properties

Methods

URL Methods

Header Methods

Body Methods

Other Methods

Bruno Object (bru)

Common Patterns

Authentication

Dynamic Request Body

Conditional Logic

URL Manipulation

Next Steps

Post-response Scripts

Test API

​Available Objects

​Request Object (req)

​Properties

​Methods

​URL Methods

​Header Methods

​Body Methods

​Other Methods

​Bruno Object (bru)

​Common Patterns

​Authentication

​Dynamic Request Body

​Conditional Logic

​URL Manipulation

​Next Steps

Post-response Scripts

Test API

Available Objects

Request Object (req)

Properties

Methods

URL Methods

Header Methods

Body Methods

Other Methods

Bruno Object (bru)

Common Patterns

Authentication

Dynamic Request Body

Conditional Logic

URL Manipulation

Next Steps