How to Get a Contract's First Transfer Event

This tutorial uses the alchemy_getAssetTransfers endpoint.

One of the best ways to study a smart contract is to look at its transfer events. In this tutorial, we will query the very first transfer event of the BAYC smart contract. However, you are welcome to use any contract address you are interested in!

See the following for use cases for retrieving a contract’s first transfer event:

Finding the first addresses to interact with a contract (e.g., the first address to mint a Bored Ape).
Tracking the first interaction an address had with a smart contract.
Verifying whether a contract facilitated transfers before a certain date.

If you already completed “How to get a contract’s last transfer event”, you may skip the setup and installation steps.

Install Node.js

Head to Node.js and download the LTS version.

You can verify your installation was successful by running npm -version in your macOS terminal or Windows command prompt. A successful installation will display a version number, such as:

shell

$ 6.4.1

Setup Project Environment

Open VS Code (or your preferred IDE) and enter the following in a terminal:

shell

$ mkdir contract-transfers
> cd contract-transfers

Once inside our project directory, initialize npm (node package manager) with the following command:

shell

$ npm init

Press enter and answer the project prompt as follows:

contract-transfers.json

1 package name: (contract-transfers)
2 version: (1.0.0)
3 description: 
4 entry point: (index.js)
5 test command: 
6 git repository: 
7 keywords: 
8 author: 
9 license: (ISC)

Press enter again to complete the prompt. If successful, a package.json file will have been created in your directory.

Setup for API Calls

We’ll use the built-in fetch API (available in Node.js 18+) to interact with Alchemy’s endpoints and make JSON-RPC requests. No additional dependencies are required!

Get Contract’s First Transfer Event

In this section, we will use Alchemy’s Transfer API to retrieve the contract’s first transfer event. We can call the alchemy_getAssetTransfers function and filter transfers by passing in the following object parameters:

Property	Description	Requirement	Default
`fromBlock`	Indicates from which block the endpoint searches. Inclusive and can be a hex string, integer, or `latest`.	Optional	`"0x0"`
`toBlock`	Indicates to which block the endpoint searches. Inclusive and can be a hex string, integer, or `latest`.	Optional	`latest`
`fromAddress`	Indicates the sending address in the transaction. Can be a hex string.	Optional	Wildcard - any address
`toAddress`	Indicates the receiving address in the transaction. Can be a hex string.	Optional	Wildcard - any address
`contractAddresses`	An array of contact addresses to filter for. Note: Only applies to transfers of `token`, `erc20`, `erc721`, and `erc1155`.	Optional	Wildcard - any address
`category`	An array of transfer categories. Can be any of the following: `external`, `internal`, `erc20`, `erc721`, or `erc1155`.	Required
`excludeZeroValue`	A boolean to exclude transfers of zero value. A zero value is not the same as `null`.	Optional	`true`
`maxCount`	The maximum number of results to return per call. Note: 1000 is the max per request.	Optional	`1000 or 0x3e8`
`pageKey`	Use for pagination. If more results are available after the response, a `uuid` property will return. You can use this in subsequent requests to retrieve the next 1000 results of `maxCount`.	Optional

For reference, here is an example of how the above parameters could be passed into the alchemy_getAssetTransfers API:

FirstTransfer.js

1 // Using fetch for alchemy_getAssetTransfers API
2 const response = await fetch(`https://eth-mainnet.g.alchemy.com/v2/${apiKey}`, {
3   method: 'POST',
4   headers: { 'Content-Type': 'application/json' },
5   body: JSON.stringify({
6     jsonrpc: '2.0',
7     id: 1,
8     method: 'alchemy_getAssetTransfers',
9     params: [{
10       fromBlock: "0x0",
11       toBlock: "latest",
12       contractAddresses: ["0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d"],
13       excludeZeroValue: true,
14       category: ["erc721"]
15     }]
16   })
17 });
18 
19 const data = await response.json();

To get started finding a contract’s first transfer, let’s create a file inside our project folder named FirstTransfer.js and add the following code to utilize the alchemy_getAssetTransfers endpoint:

FirstTransfer.js

1 // Replace with your Alchemy API Key
2 const apiKey = "demo";
3 const baseURL = `https://eth-mainnet.g.alchemy.com/v2/${apiKey}`;
4 
5 const getFirstTransfer = async () => {
6   try {
7     // Calling the getAssetTransfers endpoint with filters
8     const requestBody = {
9       jsonrpc: "2.0",
10       id: 0,
11       method: "alchemy_getAssetTransfers",
12       params: [{
13         fromBlock: "0x0",
14         contractAddresses: ["0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d"], // You can replace with contract of your choosing
15         excludeZeroValue: true,
16         category: ["erc721"]
17       }]
18     };
19 
20     const response = await fetch(baseURL, {
21       method: 'POST',
22       headers: {
23         'Content-Type': 'application/json'
24       },
25       body: JSON.stringify(requestBody)
26     });
27 
28     const data = await response.json();
29 
30     if (data.error) {
31       console.error('Error:', data.error);
32       return;
33     }
34 
35     // printing the first indexed transfer event to console
36     console.log("First Transfer:", data.result.transfers[0]);
37   } catch (error) {
38     console.error('Request failed:', error);
39   }
40 };
41 
42 getFirstTransfer();

Above, we created an async function called getFirstTransfer. To learn more about how what it does, view the commented notes above.

To use your script, run the following command in your terminal:

shell

$ node FirstTransfer.js

If successful, you should see the following transfer object in your output:

output

1 First Transfer: {
2   blockNum: '0xbb933a',
3   hash: '0xcfb197f62ec5c7f0e71a11ec0c4a0e394a3aa41db5386e85526f86c84b3f2796',
4   from: '0x0000000000000000000000000000000000000000',
5   to: '0xaba7161a7fb69c88e16ed9f455ce62b791ee4d03',
6   value: null,
7   erc721TokenId: '0x0000000000000000000000000000000000000000000000000000000000000000',
8   erc1155Metadata: null,
9   tokenId: '0x0000000000000000000000000000000000000000000000000000000000000000',
10   asset: 'BAYC',
11   category: 'erc721',
12   rawContract: {
13     value: null,
14     address: '0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d',
15     decimal: null
16   }
17 }

Congratulations, you’ve successfully retrieved the first transfer event in the BAYC contract!

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