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

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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.

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Request Object (req)

The req object represents the outgoing HTTP request.

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Properties

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req.url
string
The request URL
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req.method
string
HTTP method (GET, POST, PUT, DELETE, etc.)
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req.headers
object
Request headers as key-value pairs
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req.body
any
Request body (automatically parsed if JSON)
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req.timeout
number
Request timeout in milliseconds
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req.name
string
Name of the request
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req.pathParams
array
Path parameters array
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req.tags
array
Tags associated with the request

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Methods

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URL Methods

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req.getUrl()
function
Returns the full request URL
const url = req.getUrl();
console.log('Sending request to:', url);
​
req.setUrl(url)
function
Sets the request URLParameters:
  • url (string) - The new URL
req.setUrl('https://api.example.com/v2/users');
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req.getHost()
function
Returns the host from the URL (including port)
const host = req.getHost();
// Returns: "api.example.com:443"
​
req.getPath()
function
Returns the path portion of the URL (with path params interpolated)
const path = req.getPath();
// Returns: "/api/users/123"
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req.getQueryString()
function
Returns the query string without the leading ?
const query = req.getQueryString();
// Returns: "page=1&limit=10"

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Header Methods

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req.getHeader(name)
function
Gets a specific header valueParameters:
  • name (string) - Header name
const authHeader = req.getHeader('Authorization');
​
req.setHeader(name, value)
function
Sets a header valueParameters:
  • name (string) - Header name
  • value (string) - Header value
req.setHeader('Authorization', 'Bearer ' + token);
req.setHeader('Content-Type', 'application/json');
​
req.deleteHeader(name)
function
Removes a headerParameters:
  • name (string) - Header name
req.deleteHeader('X-Debug');
​
req.getHeaders()
function
Returns all headers as an object
const headers = req.getHeaders();
console.log('All headers:', headers);
​
req.setHeaders(headers)
function
Replaces all headersParameters:
  • headers (object) - New headers object
req.setHeaders({
  'Authorization': 'Bearer token',
  'Content-Type': 'application/json'
});
​
req.deleteHeaders(names)
function
Removes multiple headersParameters:
  • names (array) - Array of header names
req.deleteHeaders(['X-Debug', 'X-Test']);

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Body Methods

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req.getBody(options)
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 });
​
req.setBody(data, options)
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: '[email protected]'
});

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

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Other Methods

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req.getMethod()
function
Returns the HTTP method
const method = req.getMethod();
// Returns: "POST"
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req.setMethod(method)
function
Sets the HTTP methodParameters:
  • method (string) - HTTP method (GET, POST, etc.)
req.setMethod('PUT');
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req.getTimeout()
function
Returns the request timeout in milliseconds
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req.setTimeout(timeout)
function
Sets the request timeoutParameters:
  • timeout (number) - Timeout in milliseconds
req.setTimeout(30000); // 30 seconds
​
req.setMaxRedirects(max)
function
Sets the maximum number of redirects to followParameters:
  • max (number) - Maximum redirects
req.setMaxRedirects(5);
​
req.getAuthMode()
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');
}
​
req.getName()
function
Returns the request name
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req.getPathParams()
function
Returns array of path parameters
const params = req.getPathParams();
// Returns: [{name: 'id', value: '123', type: 'path'}]
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req.getTags()
function
Returns array of request tags
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req.getExecutionMode()
function
Returns the execution mode (e.g., ‘cli’, ‘gui’)
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req.onFail(callback)
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');
});
​
req.disableParsingResponseJson()
function
Disables automatic JSON parsing of the response body
// Keep response as raw string
req.disableParsingResponseJson();

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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

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Common Patterns

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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}`);
}

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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);
}

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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');
  }
}

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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());
}

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Next Steps

Post-response Scripts

Process responses and extract data

Test API

Write test assertions

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