> ## Documentation Index
> Fetch the complete documentation index at: https://docs.requestly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Iteration Data (rq.iterationData)

> Access data from CSV or JSON files during collection runs in Requestly API client scripts.

The `rq.iterationData` object provides access to data from CSV or JSON files when running collections with the Collection Runner. Each iteration of the collection run receives a different row (CSV) or object (JSON) from the data file, allowing you to parameterize your requests dynamically.

<Note>
  This feature works only when you run a collection with an attached data file, which is supported exclusively in the **Desktop App**. If you run a single request or a collection without a data file, rq.iterationData remains **undefined**.
</Note>

## Methods

### `rq.iterationData.get(key)`

Retrieves the value for a specific key from the current iteration's data.

**Parameters:**

* `key` (string): The name of the variable/column to retrieve

**Returns:** The value associated with the key, or `undefined` if the key doesn't exist

**Example:**

```javascript theme={null}
// For a CSV with columns: city, temperature
const city = rq.iterationData.get("city");
const temp = rq.iterationData.get("temperature");

console.log(`Weather in ${city}: ${temp}°C`);
// Output: Weather in Vancouver: 10°C
```

### `rq.iterationData.has(key)`

Checks if a specific key exists in the current iteration's data.

**Parameters:**

* `key` (string): The name of the variable/column to check

**Returns:** `true` if the key exists, `false` otherwise

**Example:**

```javascript theme={null}
if (rq.iterationData.has("userId")) {
    const userId = rq.iterationData.get("userId");
    console.log("User ID:", userId);
} else {
    console.log("No user ID in this iteration");
}
```

### `rq.iterationData.unset(key)`

Removes a specified variable from the iteration data during the the specific iteration.

### `rq.iterationData.toObject()`

Returns all data from the current iteration as a JavaScript object.

**Returns:** An object containing all key-value pairs from the current iteration

**Example:**

```javascript theme={null}
const allData = rq.iterationData.toObject();
console.log("Current iteration data:", allData);
// Output: Current iteration data: { city: "Vancouver", temperature: 10 }
```

## Use Cases

### Conditional Logic Based on Data

```javascript theme={null}
// Pre-request script
const userType = rq.iterationData.get("userType");

if (userType === "admin") {
    rq.request.headers.push({
        key: "X-Admin-Token",
        value: "admin-secret-token"
    });
} else {
    rq.request.headers.push({
        key: "X-User-Token",
        value: "user-token"
    });
}
```

### Validating Response Against Expected Data

```javascript theme={null}
// Post-response script
const expectedStatus = rq.iterationData.get("expectedStatus");
const actualStatus = rq.response.code;

rq.test(`Status code matches expected (${expectedStatus})`, function() {
    rq.expect(actualStatus).to.equal(parseInt(expectedStatus));
});
```

## Data File Format Examples

### CSV Format

```csv theme={null}
city,temperature,humidity
Vancouver,10,75
Austin,24,60
London,12,80
```

**Accessing in script:**

```javascript theme={null}
const city = rq.iterationData.get("city");        // "Vancouver"
const temp = rq.iterationData.get("temperature"); // 10
const humidity = rq.iterationData.get("humidity"); // 75
```