I am trying to detect timestamp in Ethereum node but there are no methods/functions.
How do we find this?
I am getting swap logs and parsing them but couldn't find direct way to detect contract creation date.
Contract creation date is not available using a direct method.
Blockchain explorers usually collect it the following way:
They scan every transaction on every block on the chain
If the transaction receipt contains non-null contractAddress property, it means that this transaction deployed a contract.
Time of the transaction (and effectively time of the contract deployment) is available as part of the block in which the tx was produced
This is quite complicated. There is no method to get the Transaction that deployed the Contract.
First of all, there are multiple ways to deploy a contract:
Via the Deployment Transaction, here you will get the contractAddress in the tx receipt.
Via another contract, with create2/create method. For example in this way Uniswap: Factory Contract creates Pair contracts. And there is no API in RPC to find out this type of deployment. You need a node that can return such "Internal Calls".
There are some workarounds. In your case, do you just need the timestamp? Then you have just to find the block when the contract was deployed.
The archive node.
Use binary search to find the block number, when eth_getCode returns not the empty data, and the previous one is empty.
Get the timestamp of the block.
If you need the transaction:
Use the previous method to find the block
Load transactions and their receipts.
Search for a Deployment Transaction, which has your contractAddress in the receipt.
If not found, almost always the contract emits an Event when creating another contract. So look into the address, data and topics to match your contract address of every log entry.
Not a universal workaround: if you know the Event which gets emitted in the constructor or by the parent's contract, you can search for it with getPastLogs.
You can use the 3rd party API, like https://docs.etherscan.io/api-endpoints/contracts to get the Get Contract Creator and Creation Tx Hash. After that:
Get the blockNumber from transaction fetched by txHash.
Get the timestamp from block fetched by blockNumber.
Related
In following code:
console.log("Deploying contract....");
const simpleStorage = await simpleStorageFactory.deploy();
await simpleStorage.deployed();
Line 2 deploys the contract and we get hold of it.
Why do we need to call deployed method in Line3?
calling deploy() will create the transaction, and you can get the contract address immediately, however this does not mean the transaction has been processed and included within a block.
deployed() will wait until it has been. Under the hood it will poll the blockchain until the contract has been succesfully processed. See: https://github.com/ethers-io/ethers.js/blob/master/packages/contracts/src.ts/index.ts#L824
I don't think you technically have to call deployed(), but if you need to do anything after the contract has been deployed and need to make sure it has been included in a mined block, then waiting for deployed() is advised.
If you go to this transaction page on etherscan, scroll down to the Input Data section and click the Decode Input Data button- it gives you nothing, which I can only assume means that etherscan was unable to decode the input data given the ABI for that contract.
My question is, why? What is special about that contract/ABI (or really any contract like this one) that would prevent the transaction from being decoded?
The called function signagure is 0xfaa916d3, the rest of the data are arguments. The contract ABI doesn't define any function that would translate to the 0xfaa916d3 signature. Which means that the fallback function was called.
In this case, the fallback function acts as a proxy, creates an internal transaction and delegates the call to the target contract (which can theretically do the same or create multiple other internal transactions, etc.)
However, Etherscan currently only compares the signature to the ABI of the root transaction recipient and ignores the internal transactions recipients' ABIs in the "Decode input data" feature.
Why? My guess is that it's easier to scan just one level, and not that high priority to implement and account for all the edge cases such as multiple internal calls with the same signature. But you'd need to ask them for the real reason. :)
Suppose an ethereum smart contract has external function "foo" whose logic has state-reverting exception require(1 == 0, 'error: you broke the simulation!');.
If ethereum-client A broadcasts transaction "txA" which is a function call on foo, how can ethereum-client B access the state-reverting message corresponding to "txA"?
edit: by "how can", I mean how can a developer practically enable ethereum-client B to access this data. i.e. Can you please point me in the direction of the correct (lower-level.. not webui) api/rpc call from a particular tool?
Clearly this is possible since block explorers provide such messages for failed transactions. I read through some of the source of etherscan, but their javascript is minimized and not easily readable.
Thanks in advance!
See this: https://ethereum.stackexchange.com/questions/39817/are-failed-transactions-included-in-the-blockchain
Failed transactions often are included in the chain.
What you sometimes see, if you're using e.g. MetaMask, is a popup saying "this transaction will fail" that happens before the transaction is sent to the chain. This is MetaMask trying to be helpful and prevent you wasting gas. But you can force send the transaction anyway, and you'll get a failed/reverted transaction posted on-chain (like this one for this Solidity source).
So to answer the original question, if TxA was posted on-chain, then client B will process it and get the revert message itself. If TxA was not posted on-chain, then there is no record of it.
When we call a solidity function via web3js, how does the code flows along with data formats during all the process?
For example, if I call a solidity function through web3js, how does it get executed. Can anyone explain the complete flow?
First of all, I recommend taking the time to read How does Ethereum work, anyway?
But for now, a short explanation
When you call a method on a contract through web3.js, the library
will encode your method call as data attribute on the transaction.
Here's a good explanation about ethereum transactions and data
attribute
The ethereum node your web3.js is connected to will receive your transactions and do some basic checks of nonce and balance
Once the basic checks pass, the node will broadcast the transaction to the rest of the network
When a network node receives a transaction with data attribute, it will execute the transaction using the Ethereum EVM. The outcome
of the transaction is modified state of the contract storage. More
about contract storage
The expectation is that the transaction will produce the same state change on every single node in the network. This is how
consensus is reached and the transaction (and the contract state
change) become part of the canonical chain (mined and not belonging
to an uncle block)
I am using testrpc and truffle to test my smart contract before deploying it to the real network.
In my contract, each node has to register in the contract by calling the function register, after that he can send or receive messages to/from contract( the blockchain )
The problem is, when an address ( let say account 1 from testrpc accounts) call the functions (send or receive ) the transaction doesn't occur and this message appears
VM Exception while processing transaction: invalid JUMP at
But when I use another unregistered account to call this function, it works.
Although no messages have been sent or received but no exceptions..
Any idea how I can solve this.
Thanks
Unless your using an old version of solc to compile your solidity the chance of this being an optimization problem is almost none.
Now, what does this mean then, it can happen when for example you run a modifier and it doesn't work. or if you try to call a function you are not allowed to and it throws. For example, it happens a lot after an ICO finishes and you try to use a function that can't be used anymore due to a date constraint it returns an Invalid Jump
I can't see your code but I think you might have reversed your if condition in your modifier and now it returns true if the user is not registered.