# Get a Random Value from API

## Prerequisite

Before integrating Oraichain VRF 2.0 into your tech stack, you need to install **Oraichain cosmosjs library**. Kindly follow the steps as demonstrated [here](https://www.npmjs.com/package/@oraichain/cosmosjs).

## Integration steps

### For Back-end Usage

#### Step 1: **Import Oraichain cosmosjs library**

```smali
const Cosmos = require("@oraichain/cosmosjs").default;

const lcdUrl = "https://lcd.orai.io";
const chainId = "Oraichain";
const mnemonic = "foo bar";
const requestFees = “100”;

const message = Cosmos.message;
const cosmos = new Cosmos(lcdUrl, chainId);
const childKey = cosmos.getChildKey(mnemonic);
const sender = cosmos.getAddress(mnemonic);

cosmos.setBech32MainPrefix('orai');
```

#### **Step 2:** Request a random transaction

```
const input = Buffer.from(
       JSON.stringify({
           request_random: {
               input: btoa(userInput),
           },
       })
   );
 
const txBody = getHandleMessage(contract, input, sender, requestFees);
const response = await cosmos.submit(childKey, txBody, "BROADCAST_MODE_BLOCK", isNaN(fees) ? 0 : parseInt(fees), gas);
```

Enter a string value of your preference at ***userInput***. You will see the fee for your request at ***requestFees***. Also, maximum gas and tx fee need to be decided before each request.

:warning: In the unlikely case that your request takes too long to respond, try switching "**BROADCAST\_MODE\_BLOCK"** to ***"*****BROADCAST\_MODE\_SYNC"**, and use tx hash to query until it is included on-chain.

Regarding how to query tx hash, please refer to [this example](https://lcd.orai.io/cosmos/tx/v1beta1/txs/%7Btx_hash%7D) or [this](https://lcd.orai.io/cosmos/tx/v1beta1/txs/397FAFB6973CC0717773290E3F0A0FF2101EDD4689AD983052C60AA3CF8AA5C0).

#### Step 3: Get a random round number

```
const round = response.tx_response.logs[0].events[1].attributes[3].value;
```

#### Step 4: **Get the information from a round**

```
const queryRoundInput = JSON.stringify({
       get_round: {round: parseInt(round)},
   });
 
   const roundOutput = await cosmos.get(`/wasm/v1beta1/contract
/${contract}/smart/${Buffer.from(queryRoundInput).toString("base64")}`);
```

***contract*** is the contract address of the VRF issued by Oraichain and can be reviewed on Oraiscan any time\*\*.\*\*

If the round result has not displayed the randomness output, you just need to wait for some time before querying again.

### **For browser usage**

#### **Step 1: Import Oraichain cosmosjs library**

```
import Cosmos from "@oraichain/cosmosjs";
const lcdUrl = "https://lcd.orai.io";
const chainId = "Oraichain";
const requestFees = “100”;

const message = Cosmos.message;
const cosmos = new Cosmos(lcdUrl, chainId);
```

#### Step 2: Import keystation for wallet use by creating a new js file

```
// @ts-nocheck
/* eslint-disable eqeqeq */
// Find Left Boundry of the Screen/Monitor
function FindLeftScreenBoundry() {
   // Check if the window is off the primary monitor in a positive axis
   // X,Y                  X,Y                    S = Screen, W = Window
   // 0,0  ----------   1280,0  ----------
   //     |          |         |  ---     |
   //     |          |         | | W |    |
   //     |        S |         |  ---   S |
   //      ----------           ----------
   if (window.leftWindowBoundry() > window.screen.width) {
       return window.leftWindowBoundry() - (window.leftWindowBoundry() - window.screen.width);
   }
 
   // Check if the window is off the primary monitor in a negative axis
   // X,Y                  X,Y                    S = Screen, W = Window
   // 0,0  ----------  -1280,0  ----------
   //     |          |         |  ---     |
   //     |          |         | | W |    |
   //     |        S |         |  ---   S |
   //      ----------           ----------
   // This only works in Firefox at the moment due to a bug in Internet Explorer opening new windows into a negative axis
   // However, you can move opened windows into a negative axis as a workaround
   if (window.leftWindowBoundry() < 0 && window.leftWindowBoundry() > window.screen.width * -1) {
       return window.screen.width * -1;
   }
 
   // If neither of the above, the monitor is on the primary monitor whose's screen X should be 0
   return 0;
}
 
window.leftScreenBoundry = FindLeftScreenBoundry;
 
function PopupCenter(url, title, w, h) {
   const newWindow = window.open(
       url,
       title,
       "resizable=1, scrollbars=1, fullscreen=0, height=" +
       h +
       ", width=" +
       w +
       ", screenX=" +
       window.leftScreenBoundry +
       " , left=" +
       window.leftScreenBoundry +
       ", toolbar=0, menubar=0, status=1"
   );
   return newWindow;
}
 
function openWindowV1(type, payload, account = "", self) {
   console.log(`open ${self.client}`);
 
   // The account parameter is required for users having multiple keychain accounts.
   let apiUrl = "";
   switch (type) {
       case "signin":
           apiUrl = "signin";
           break;
       case "transaction":
           apiUrl = "tx";
           break;
       default:
           apiUrl = "signin";
           break;
   }
 
   return PopupCenter(
       self.keystationUrl +
       "/" +
       apiUrl +
       "?account=" +
       encodeURIComponent(account) +
       "&client=" +
       encodeURIComponent(self.client) +
       "&lcd=" +
       encodeURIComponent(self.lcd) +
       "&path=" +
       encodeURIComponent(self.path) +
       "&payload=" +
       encodeURIComponent(JSON.stringify(payload)),
       "",
       "470",
       "760"
   );
}
 
function openWindowV2(type, payload, account = "", self) {
   console.log(`open ${self.client}`);
 
   // The account parameter is required for users having multiple keychain accounts.
   let apiUrl = "";
   switch (type) {
       case "signin":
           apiUrl = "signin";
           break;
       case "transaction":
           apiUrl = "transaction";
           break;
       case "ai-request":
           apiUrl = "ai_request/set";
           break;
       default:
           apiUrl = "auth";
           break;
   }
 
   const network = "Oraichain";
   return PopupCenter(
       self.keystationUrl +
       "/" +
       apiUrl +
       "?lcd=" +
       encodeURIComponent(self.lcd) +
       "&raw_message=" +
       encodeURIComponent(JSON.stringify(payload)) +
       "&signInFromScan=true" +
       "&network=" +
       network,
       "",
       "470",
       "760"
   );
}
 
export default class Keystation {
   constructor(params) {
       if (!params) {
           return;
       }
       const { client, lcd, path, keystationUrl } = params;
       this.client = client;
       this.lcd = lcd;
       this.path = path;
 
       this.keystationUrl = keystationUrl;
   }
 
   openWindow(type, payload, account = "") {
       const self = this;
       return process.env.REACT_APP_WALLET_VERSION == 2 ? openWindowV2(type, payload, account, self) : openWindowV1(type, payload, account, self);
   }
}
 
export const myKeystation = new Keystation({
   client: "https://api.wallet.orai.io",
   lcd: "https://lcd.orai.io",
   path: "44/118/0/0/0",
   keystationUrl: "https://api.wallet.orai.io",
});
```

#### Step 3: **Create a randomness request**

```
const input = Buffer.from(
       JSON.stringify({
           request_random: {
               input: btoa(userInput),
           },
       })
   );
 
const {privateKey, chainCode, network} = await getChildKey();
const childKey = fromPrivateKey(Buffer.from(privateKey), Buffer.from(chainCode), network);
 
const sender = cosmos.getAddress(childKey);
 
 
const txBody = getHandleMessage(contract, input, sender, requestFees);
const response = await cosmos.submit(childKey, txBody, "BROADCAST_MODE_BLOCK", isNaN(fees) ? 0 : parseInt(fees), gas);
```

Function ***getChildKey()*** is as follow:

```
   // const popup = window.open(`${config.walletapi}/auth?signInFromScan=true`, "", "resizable=1, scrollbars=1, fullscreen=0, width=470, height=760");
   const popup = myKeystation.openWindow("auth", "");
 
   return new Promise((resolve, reject) => {
       const loop = setInterval(function() {
           if (!popup) {
               clearInterval(loop);
               reject("window-blocked");
           } else if (popup.closed) {
               clearInterval(loop);
               reject("window-closed");
           }
       }, 500);
       const handler = e => {
           if (e.data.privateKey && e.data.chainCode && e.data.network) {
               clearInterval(loop);
               window.removeEventListener("message", handler);
               resolve(e.data);
           }
       };
       window.addEventListener("message", handler);
   });
};
```

#### **Step 4: Repeat the previously mentioned step 3 and 4 to get the random value and round information**


---

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

```
GET https://docs.orai.io/developer-guides/vrf/get-a-random-value-from-api.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.