# Example - Pick a Property

The `PickPropertyExample`contract illustrates the utilization of `GeneralRandcastConsumerBase` and [`RandcastSDK`](/randcast/using-the-sdk/randcast-utilities.md) to pick one of several predefined properties. 

```solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;

import {
    GeneralRandcastConsumerBase,
    BasicRandcastConsumerBase
} from "randcast-user-contract/user/GeneralRandcastConsumerBase.sol";
// solhint-disable-next-line no-global-import
import "randcast-user-contract/user/RandcastSDK.sol" as RandcastSDK;

contract PickPropertyExample is GeneralRandcastConsumerBase {
    /* requestId -> randomness */
    mapping(bytes32 => uint256) public randomResults;
    mapping(uint256 => string) public propertyValue;
    uint256 public indexResult;
    event PropertyValueResult(string);
    
    constructor(address controller) BasicRandcastConsumerBase(controller) {
        propertyValue[0] = "fire";
        propertyValue[1] = "wind";
        propertyValue[2] = "water";
    }

    /**
     * Requests randomness
     */
    function getProperty() external returns (bytes32) {
        bytes memory params;
        return _requestRandomness(RequestType.Randomness, params);
    }

    /**
     * Callback function used by Randcast Adapter
     */
    // solhint-disable-next-line
    function _fulfillRandomness(bytes32 requestId, uint256 randomness) internal override {
        randomResults[requestId] = randomness;
        uint256 propertyIndex = RandcastSDK.roll(randomness, 3);
        indexResult = propertyIndex;
        emit PropertyValueResult(propertyValue[propertyIndex]);
    }
}

```

The contract structure is similar to the previous example. The main components include the `constructor`, the function `getProperty` which is used to request random numbers, and the callback function `_fulfillRandomness` which is triggered after generating the random number.

In the `constructor`, define each index to represent the properties of 'fire,' 'wind,' and 'water.'

The function `getProperty`  requests the random number to be used in the callback function.

In the callback function `_fulfillRandomness`we call `RandcastSDK.roll` to pick the index of the three properties. We can then get the property value by index from the `propertyValue` mapping.

The reason to choose this [`RandcastSDK`](/randcast/using-the-sdk/randcast-utilities.md) function in this example is that we need to select one of the three properties with equal probability randomly, and `RandcastSDK.roll` is designed for randomly picking a number within a specified range.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.arpanetwork.io/randcast/using-the-sdk/consumer-contract-examples/example-pick-a-property.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.