Metamask: Why does the `buyNode` function in my contract process in ETH instead of USDT, even though I’m explicitly passing USDT as the payment token parameter?

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Understanding Metamask and USDT in Smart Contract Transactions

As a developer building decentralized applications (dApps) on the Ethereum blockchain, you’re likely familiar with smart contracts and their interactions with various external services. One such service that facilitates transactions is MetaMask, a popular browser extension for Ethereum users.

In this article, we’ll explore why the buyNode function in your contract processes in ETH instead of USDT, despite explicitly passing USDT as the payment token parameter.

The buyNode Function: A Key Component

The buyNode function is a crucial component of your smart contract. Its purpose is to acquire new nodes from the Ethereum Network, allowing users to access decentralized applications (dApps) that rely on these nodes for their functionality.

When you call the buyNode function with USDT as the payment token, MetaMask attempts to execute the transaction and pay the Ether price of USDT in ETH. This process is facilitated by the Ethereum Virtual Machine (EVM), which converts the USDT into ETH using the smart contract’s built-in conversion rate.

The Problem: Conversion Rate vs. Price

However, there’s a catch. The buyNode function doesn’t convert USDT to ETH directly; it instead relies on an external service called MetaMask’s convertFromETH method, which converts ETH to USDT at the current market price (i.e., 0.000025 USD/ETH).

This conversion rate is not fixed and can fluctuate based on market conditions. As a result, even when you explicitly pass USDT as the payment token parameter, MetaMask may choose to convert it into ETH before processing your transaction.

Why the Difference in Conversion Rate?

The key reason for this difference lies in how MetaMask’s buyNode function is implemented. When using the buyNode function, MetaMask needs to find a new node on the Ethereum Network that supports the USDT conversion rate used by your contract. This process involves querying multiple nodes and selecting one that matches the desired conversion rate.

In contrast, when you explicitly pass USDT as the payment token parameter, MetaMask can use its own built-in conversion rate without relying on an external service like convertFromETH. However, this means that the conversion rate used by your contract is not always the same as the current market price.

Conclusion

To avoid potential issues with conversion rates and ensure that your smart contracts work correctly in different scenarios, it’s essential to understand how MetaMask handles USDT payment tokens. In summary:

• When using the buyNode function, MetaMask converts USDT to ETH at the current market price (i.e., 0.000025 USD/ETH).

• Even when passing USDT as the payment token parameter explicitly, MetaMask may choose to convert it into ETH before processing your transaction.

• To ensure reliable smart contract transactions, you should explore alternative methods or solutions that bypass these conversion rate issues.

I hope this article has helped clarify the situation and provided valuable insights for developers building decentralized applications on the Ethereum blockchain.

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