Smart Contract GraphQL

This is a stateless smart contract event watcher exposing a GraphQL API. You can use it to monitor events from an already deployed smart contract using a GraphQL client.

Please note that you can perform the same tasks client side using web3 filters API instead of this project.

Getting the source code

You need dep

go get github.com/kivutar/smart-contract-graphql
cd $GOPATH/src/github.com/kivutar/smart-contract-graphql
dep ensure

Building and running locally

go build && PORT=3000 RPC_ENDPOINT="wss://rinkeby.infura.io/ws" ./smart-contract-graphql

Example query

query {
  filterLogs (name: "Message", address: "0x5e626b58388f8b083d6d399f385c901675636b6e", abi: "[{ \"constant\": false, \"inputs\": [{ \"name\": \"_hashContent\", \"type\": \"string\" }, { \"name\": \"_hashImage\", \"type\": \"string\" }], \"name\": \"post\", \"outputs\": [], \"payable\": false, \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"constant\": true, \"inputs\": [{ \"name\": \"\", \"type\": \"uint256\" }], \"name\": \"hashes\", \"outputs\": [{ \"name\": \"sender\", \"type\": \"address\" }, { \"name\": \"content\", \"type\": \"string\" }, { \"name\": \"image\", \"type\": \"string\" }, { \"name\": \"timestamp\", \"type\": \"uint256\" }], \"payable\": false, \"stateMutability\": \"view\", \"type\": \"function\" }, { \"constant\": true, \"inputs\": [], \"name\": \"lastHashId\", \"outputs\": [{ \"name\": \"\", \"type\": \"uint256\" }], \"payable\": false, \"stateMutability\": \"view\", \"type\": \"function\" }, { \"constant\": false, \"inputs\": [{ \"name\": \"_hashAvatar\", \"type\": \"string\" }], \"name\": \"set_avatar\", \"outputs\": [], \"payable\": false, \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"constant\": true, \"inputs\": [{ \"name\": \"\", \"type\": \"address\" }], \"name\": \"avatars\", \"outputs\": [{ \"name\": \"\", \"type\": \"string\" }], \"payable\": false, \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [], \"payable\": false, \"stateMutability\": \"nonpayable\", \"type\": \"constructor\" }, { \"anonymous\": false, \"inputs\": [{ \"indexed\": true, \"name\": \"sender\", \"type\": \"address\" }, { \"indexed\": false, \"name\": \"id\", \"type\": \"uint256\" }, { \"indexed\": false, \"name\": \"cid\", \"type\": \"string\" }, { \"indexed\": false, \"name\": \"img\", \"type\": \"string\" }, { \"indexed\": false, \"name\": \"timestamp\", \"type\": \"uint256\" }], \"name\": \"Message\", \"type\": \"event\" }, { \"anonymous\": false, \"inputs\": [{ \"indexed\": true, \"name\": \"sender\", \"type\": \"address\" }, { \"indexed\": false, \"name\": \"cid\", \"type\": \"string\" }], \"name\": \"Avatar\", \"type\": \"event\" }]") {
    Topics
    Data
    TxHash
    BlockNumber
    BlockHash
    Index
    TxIndex
    Address
    Removed
    Values
  }
}

Example subscription

subscription {
  watchLogs (name: "Message", address: "0x5e626b58388f8b083d6d399f385c901675636b6e", abi: "[{ \"constant\": false, \"inputs\": [{ \"name\": \"_hashContent\", \"type\": \"string\" }, { \"name\": \"_hashImage\", \"type\": \"string\" }], \"name\": \"post\", \"outputs\": [], \"payable\": false, \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"constant\": true, \"inputs\": [{ \"name\": \"\", \"type\": \"uint256\" }], \"name\": \"hashes\", \"outputs\": [{ \"name\": \"sender\", \"type\": \"address\" }, { \"name\": \"content\", \"type\": \"string\" }, { \"name\": \"image\", \"type\": \"string\" }, { \"name\": \"timestamp\", \"type\": \"uint256\" }], \"payable\": false, \"stateMutability\": \"view\", \"type\": \"function\" }, { \"constant\": true, \"inputs\": [], \"name\": \"lastHashId\", \"outputs\": [{ \"name\": \"\", \"type\": \"uint256\" }], \"payable\": false, \"stateMutability\": \"view\", \"type\": \"function\" }, { \"constant\": false, \"inputs\": [{ \"name\": \"_hashAvatar\", \"type\": \"string\" }], \"name\": \"set_avatar\", \"outputs\": [], \"payable\": false, \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"constant\": true, \"inputs\": [{ \"name\": \"\", \"type\": \"address\" }], \"name\": \"avatars\", \"outputs\": [{ \"name\": \"\", \"type\": \"string\" }], \"payable\": false, \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [], \"payable\": false, \"stateMutability\": \"nonpayable\", \"type\": \"constructor\" }, { \"anonymous\": false, \"inputs\": [{ \"indexed\": true, \"name\": \"sender\", \"type\": \"address\" }, { \"indexed\": false, \"name\": \"id\", \"type\": \"uint256\" }, { \"indexed\": false, \"name\": \"cid\", \"type\": \"string\" }, { \"indexed\": false, \"name\": \"img\", \"type\": \"string\" }, { \"indexed\": false, \"name\": \"timestamp\", \"type\": \"uint256\" }], \"name\": \"Message\", \"type\": \"event\" }, { \"anonymous\": false, \"inputs\": [{ \"indexed\": true, \"name\": \"sender\", \"type\": \"address\" }, { \"indexed\": false, \"name\": \"cid\", \"type\": \"string\" }], \"name\": \"Avatar\", \"type\": \"event\" }]") {
    Topics
    Data
    TxHash
    BlockNumber
    BlockHash
    Index
    TxIndex
    Address
    Removed
    Values
  }
}

Go to http://ipfs.io/ipfs/Qma2o1KZ8z75cbSZhVhEJPHW3L4hdM1jM6PWRuoS14YJqW/ and post a message using Metamask on Rinkeby. Wait a minute, you should see your message event log in graphiql right panel.

Online demo

You can try it yourself on https://smart-contract-graphql.herokuapp.com/. The contract needs to be deployed on Rinkeby Testnet.

TODO

• Event Data decoding: Values should return a map with the right argument names and types
• Passing abi could be avoided by calling ethclient.Client.FilterLogs instead of BoundContract.FilterLogs
• Expose FilterOpts params to set the blockNumber range
• Expose query params to build complex queries
• Refactoring + tests + scaling tests