Runs an eth_call with the context of the provided block execution using the final state of the parent block as the base.

Description

traceCallruns an eth_call with the context of the provided block execution using the final state of the parent block as the base.

Parameters

Response

The traceCall method returns a response object with the following properties.

Example Request and Response

Prerequisite: You will need to install the Alchemy SDK before making requests with it.

The commands for installing it using npm or yarn are given below:

$
npm install alchemy-sdk

Request

Here is an example of how to make a traceCall request using the Alchemy SDK:

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// Imports the Alchemy SDK
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const { Alchemy, Network } = require("alchemy-sdk");
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// Configures the Alchemy SDK
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const config = {
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  apiKey: "demo", // Replace with your API key
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  network: Network.ETH_MAINNET, // Replace with your network
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};
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// Creates an Alchemy object instance with the config to use for making requests
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const alchemy = new Alchemy(config);
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// Example of using the traceCall method
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const main = async () => {
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  // The transaction to debug trace.
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  let transaction = {
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    from: "0x6f1FB6EFDf50F34bFA3F2bC0E5576EdD71631638",
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    to: "0x6b175474e89094c44da98b954eedeac495271d0f",
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    value: "0x0",
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    data: "0x70a082310000000000000000000000006E0d01A76C3Cf4288372a29124A26D4353EE51BE",
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  };
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  // The block to debug the transaction in.
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  let block = "latest";
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  // Tracer type and configuration.
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  let tracerConfig = {
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    type: "callTracer",
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    onlyTopCall: true,
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  };
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  // Calling the traceCall method
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  let response = await alchemy.debug.traceCall(
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    transaction,
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    block,
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    tracerConfig
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  );
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  // Logging the response to the console
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  console.log(response);
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};
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main();

Response

And here is an example of what a successful response to this request might look like:

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{
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  type: 'CALL',
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  from: '0x6f1fb6efdf50f34bfa3f2bc0e5576edd71631638',
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  to: '0x6b175474e89094c44da98b954eedeac495271d0f',
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  value: '0x0',
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  gas: '0x7fffffffffffac47',
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  gasUsed: '0xa2a',
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  input: '0x70a082310000000000000000000000006e0d01a76c3cf4288372a29124a26d4353ee51be',
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  output: '0x0000000000000000000000000000000000000000000000000858898f93629000'
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}

Use Cases

Some of the use cases for traceCall are:

• Debugging Contract Issues: Developers can use the traceCall method to diagnose and fix issues with smart contract execution by tracing the flow of execution and the state changes made by the contract.

• Optimizing Contract Performance: Developers can use the traceCall method to identify and optimize slow or inefficient sections of code by tracing the execution and gas consumption of smart contract calls.

• Verifying Contract Security: Security auditors can use the traceCall method to verify the security of smart contracts by tracing the execution of malicious inputs and evaluating the contract’s response.

• Improving Contract User Experience: Developers can use the traceCall method to improve the user experience of smart contract interactions by tracing the execution of user inputs and evaluating the contract’s response.

Related Methods

Here are the methods related to traceCall:

• traceTransaction: Attempts to run the transaction in the exact same manner as it was executed on the network. It will replay any transaction that may have been executed prior to this one before it and will then attempt to execute the transaction that corresponds to the given hash.
• traceBlock: Replays a block that has already been mined.