Use Geth to Access a Deployed Contract
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This document describes the process of deploying a smart contract using Remix and accessing it with Geth, the Go implementation of Ethereum. It details the steps necessary to set up a connection to a deployed contract via the contract address and ABI, and provides commands for interacting with the contract. The emphasis is on using Geth as a console for interacting with the deployed contract on a local TestRPC instance.
![Obtain ABI from Compile Panel on Remix.
ABI
[{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"retVal","type":"uint
256"}],"payable":false,"stateMutability":"view","type":"function"},
{"constant":false,"inputs":[{"name":"x","type":"uint256"}],"name":"set","outputs":
[],"payable":false,"stateMutability":"nonpayable","type":"function"}]](https://image.slidesharecdn.com/6gethaccess-180320074340/85/Use-Geth-to-Access-a-Deployed-Contract-8-320.jpg)
![To get the current value,
> simpleStorage.get()
To set a new value (note: we need to specify an account we use to execute the function.)
> simpleStorage.set(100, {from: eth.account[0]})
Note that this new value can also be seen in Remix](https://image.slidesharecdn.com/6gethaccess-180320074340/85/Use-Geth-to-Access-a-Deployed-Contract-13-320.jpg)
Use Geth to Access a Deployed Contract
- 1. 6. Use Geth to Access a Deployed Contract KC Tam Reach KC on LinkedIn: https://www.linkedin.com/in/ktam1/
- 2. Objective In this section we deploy the contract using Remix, and use Geth, a command line tool, to access it.
- 3. Geth (Go Ethereum) Geth is the official Go implementation of Ethereum. There are three implementations, using Go, Python and C++. Geth is by far the most common. A host running Geth becomes part of the Ethereum network (a node). Besides, Geth also serves as a client and accesses Ethereum node. ● In this section we are using Geth client accessing a contract deployed on TestRPC.
- 4. Ethereum Network (the Giant Computer) Review: Access Deployed Contract Deployed contract can be accessed through 1. Contract Address and 2. Application Binary Interface (ABI) Deployed Contract Bytecode ABI Contract Address Web / Mobile Frontend Contract AddressABI Access
- 5. TestRPC on Localhost Deploy the Contract ● Use Remix to deploy the SimpleStorage contract ● Obtain the Contract Address ● By default, RPC opens on port 8545 on TestRPC Deployed Contract Bytecode ABI Contract Address http://localhost:8545
- 6. First start TestRPC, and in Remix select Web3 Provider to interact with TestRPC.
- 7. Use Create to deploy the contract. Note that we see the Contract Address in both Remix and TestRPC.
- 8. Obtain ABI from Compile Panel on Remix. ABI [{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"retVal","type":"uint 256"}],"payable":false,"stateMutability":"view","type":"function"}, {"constant":false,"inputs":[{"name":"x","type":"uint256"}],"name":"set","outputs": [],"payable":false,"stateMutability":"nonpayable","type":"function"}]
- 9. TestRPC on Localhost Access the Contract ● Run Geth client accessing RPC (port 8545) ● Define an object with ABI and Contract Address ● Functions are executed through this object. Deployed Contract Bytecode ABI Contract Address geth Contract AddressABI Access object http://localhost:8545
- 10. Use another terminal and access TestRPC using RPC $ geth attach http://localhost:8545 And we can check the 10 accounts on TestRPC > eth.accounts
- 11. Keep <abi> into a variable abi. > abi = <abi>
- 12. Define an object simpleStorage with abi defined above, and the contract address. > simpleStorage = eth.contract(abi).at(<copied contract address>) Now with simpleStorage object we can access variables and functions on this deployed contract.
- 13. To get the current value, > simpleStorage.get() To set a new value (note: we need to specify an account we use to execute the function.) > simpleStorage.set(100, {from: eth.account[0]}) Note that this new value can also be seen in Remix
- 14. Summary We use Geth as a console to access a deployed contract on TestRPC. Both Remix and Geth access the same deployed contract.