Variable Interpolation

Variable interpolation in Bruno allows you to use variables in your requests using the {{variableName}} syntax. Let’s explore how interpolation works with different data types.

Basic Interpolation

Strings


// Setting a string variable
bru.setVar("greeting", "Hello World");


// Using in request
GET http://api.example.com/{{greeting}}
// Interpolates to: http://api.example.com/Hello World

Numbers


// Setting a number variable
bru.setVar("userId", 123);


// Using in request
GET http://api.example.com/users/{{userId}}
// Interpolates to: http://api.example.com/users/123

Booleans


// Setting a boolean variable
bru.setVar("isActive", true);
 
// Using in request body
{
  "active": {{isActive}}
}
// Interpolates to: { "active": true }

Object Interpolation

Object interpolation is available from Bruno v2.2.0 onwards.

You can access object properties using dot notation. Here’s how to work with objects containing different data types:


// Define your object with multiple data types
const userProfile = {
  username: "john_doe",           // string
  accountId: 12345,              // number
  isVerified: true,              // boolean
  preferences: {                  // nested object
    theme: "dark",
    notifications: true
  }
};
 
// Set the object as a variable
bru.setVar("user", userProfile);
 
// Using in request body
{
  "username": "{{user.username}}",
  "verified": {{user.isVerified}},
  "preferences": {{user.preferences}},
}
 
// Interpolates to:
// {
//   "username": "john_doe",
//   "verified": true,
//   "preferences": {
//    "theme": "dark",
//    "notifications": true
 //   }
// }

Array Interpolation

Array interpolation is available from Bruno v2.2.0 onwards.


// Define your arrays
const technologies = ["REST", "GraphQL", "gRPC"];
 
const settings = [
  { port: 3000, env: "dev" },
  { port: 8080, env: "prod" }
];
 
// Set arrays as variables
bru.setVar("apiTypes", technologies);
bru.setVar("configs", settings);
 
// Using array elements in request
{
  // Simple array access
  "primaryAPI": "{{apiTypes[0]}}",        // "REST"
  "alternativeAPI": {{apiTypes}},    
  
  // Accessing object properties in arrays
  "devPort": {{configs[0].port}},         // 3000
  "prodEnv": {{configs}},        
  
  // Using multiple array elements
  "supported": {
    "apis": ["{{apiTypes[0]}}", "{{apiTypes[1]}}"],
  }
}
 
// Interpolates to:
// {
//   "primaryAPI": "REST",
//    "alternativeAPI": [
//    "REST",
//    "GraphQL",
//    "gRPC"
//    ]
//   "devPort": 3000,
//   "prodEnv": [
//    {
//      "port": 3000,
//      "env": "dev"
//    },
//    {
//      "port": 8080,
//     "env": "prod"
//    }
//  ]
 
//   "supported": {
//     "apis": ["REST", "GraphQL"],
//   }
// }

Date Interpolation


 
// Bruno v2.2.0+
bru.setVar("timestamp", new Date());
 
// Using in request
{
  "createdAt": "{{timestamp}}"
}
// Interpolates to:
// {
//   "createdAt": "2025-04-23T13:57:56.341Z"
// }

Practical Examples

API Authentication


bru.setVar("authConfig", {
  apiKey: "your-api-key",
  secret: "your-secret"
});
 
// In request headers
headers {
  "X-API-Key": "{{authConfig.apiKey}}",
  "X-Secret": "{{authConfig.secret}}"
}

Dynamic Query Parameters


bru.setVar("searchParams", {
  limit: 10,
  offset: 0,
  filter: "active"
});


// In URL
GET http://api.example.com/users?limit={{searchParams.limit}}&offset={{searchParams.offset}}&filter={{searchParams.filter}}

Request Body with Mixed Types


bru.setVar("product", {
  name: "Bruno Pro",
  price: 99.99,
  features: ["Git Integration", "Offline First"],
  metadata: {
    version: "2.2.0",
    released: new Date()
  }
});
 
// In request body
{
  "productName": "{{product.name}}",
  "price": {{product.price}},
  "firstFeature": "{{product.features[0]}}",
  "releaseDate": "{{product.metadata.released}}"
}

Remember that variables set using bru.setVar() are available throughout your collection’s scope. Use them to make your requests more dynamic and maintainable.