Tools, FAQ, Tutorials:
BYFN Chaincode - chaincode_example02.go
What is the chaincode in Golang used in BYFN (Build Your First Network)?
✍: FYIcenter.com
The chaincode in Golang used in BYFN (Build Your First Network)
is located in the chaincode_example02.go file
and located in hyperledger-binaries/fabric-samples/chaincode/chaincode_example02/go/
directory:
$ cd hyperledger-binaries/fabric-samples $ more chaincode/chaincode_example02/go/chaincode_example02.go /* Copyright IBM Corp. 2016 All Rights Reserved. */ package main //WARNING - this chaincode's ID is hard-coded in chaincode_example04 to illustrate one way of //calling chaincode from a chaincode. If this example is modified, chaincode_example04.go has //to be modified as well with the new ID of chaincode_example02. //chaincode_example05 show's how chaincode ID can be passed in as a parameter instead of //hard-coding. import ( "fmt" "strconv" "github.com/hyperledger/fabric/core/chaincode/shim" pb "github.com/hyperledger/fabric/protos/peer" ) // SimpleChaincode example simple Chaincode implementation type SimpleChaincode struct { } func (t *SimpleChaincode) Init(stub shim.ChaincodeStubInterface) pb.Response { fmt.Println("ex02 Init") _, args := stub.GetFunctionAndParameters() var A, B string // Entities var Aval, Bval int // Asset holdings var err error if len(args) != 4 { return shim.Error("Incorrect number of arguments. Expecting 4") } // Initialize the chaincode A = args[0] Aval, err = strconv.Atoi(args[1]) if err != nil { return shim.Error("Expecting integer value for asset holding") } B = args[2] Bval, err = strconv.Atoi(args[3]) if err != nil { return shim.Error("Expecting integer value for asset holding") } fmt.Printf("Aval = %d, Bval = %d\n", Aval, Bval) // Write the state to the ledger err = stub.PutState(A, []byte(strconv.Itoa(Aval))) if err != nil { return shim.Error(err.Error()) } err = stub.PutState(B, []byte(strconv.Itoa(Bval))) if err != nil { return shim.Error(err.Error()) } return shim.Success(nil) } func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) pb.Response { fmt.Println("ex02 Invoke") function, args := stub.GetFunctionAndParameters() if function == "invoke" { // Make payment of X units from A to B return t.invoke(stub, args) } else if function == "delete" { // Deletes an entity from its state return t.delete(stub, args) } else if function == "query" { // the old "Query" is now implemtned in invoke return t.query(stub, args) } return shim.Error ("Invalid invoke function name. Expecting \"invoke\" \"delete\" \"query\"") } // Transaction makes payment of X units from A to B func (t *SimpleChaincode) invoke(stub shim.ChaincodeStubInterface, args []string ) pb.Response { var A, B string // Entities var Aval, Bval int // Asset holdings var X int // Transaction value var err error if len(args) != 3 { return shim.Error("Incorrect number of arguments. Expecting 3") } A = args[0] B = args[1] // Get the state from the ledger // TODO: will be nice to have a GetAllState call to ledger Avalbytes, err := stub.GetState(A) if err != nil { return shim.Error("Failed to get state") } if Avalbytes == nil { return shim.Error("Entity not found") } Aval, _ = strconv.Atoi(string(Avalbytes)) Bvalbytes, err := stub.GetState(B) if err != nil { return shim.Error("Failed to get state") } if Bvalbytes == nil { return shim.Error("Entity not found") } Bval, _ = strconv.Atoi(string(Bvalbytes)) // Perform the execution X, err = strconv.Atoi(args[2]) if err != nil { return shim.Error("Invalid transaction amount, expecting a integer value") } Aval = Aval - X Bval = Bval + X fmt.Printf("Aval = %d, Bval = %d\n", Aval, Bval) // Write the state back to the ledger err = stub.PutState(A, []byte(strconv.Itoa(Aval))) if err != nil { return shim.Error(err.Error()) } err = stub.PutState(B, []byte(strconv.Itoa(Bval))) if err != nil { return shim.Error(err.Error()) } return shim.Success(nil) } // Deletes an entity from state func (t *SimpleChaincode) delete(stub shim.ChaincodeStubInterface, args []string ) pb.Response { if len(args) != 1 { return shim.Error("Incorrect number of arguments. Expecting 1") } A := args[0] // Delete the key from the state in ledger err := stub.DelState(A) if err != nil { return shim.Error("Failed to delete state") } return shim.Success(nil) } // query callback representing the query of a chaincode func (t *SimpleChaincode) query(stub shim.ChaincodeStubInterface, args []string) pb.Response { var A string // Entities var err error if len(args) != 1 { return shim.Error ("Incorrect number of arguments. Expecting name of the person to query") } A = args[0] // Get the state from the ledger Avalbytes, err := stub.GetState(A) if err != nil { jsonResp := "{\"Error\":\"Failed to get state for " + A + "\"}" return shim.Error(jsonResp) } if Avalbytes == nil { jsonResp := "{\"Error\":\"Nil amount for " + A + "\"}" return shim.Error(jsonResp) } jsonResp := "{\"Name\":\"" + A + "\",\"Amount\":\"" + string(Avalbytes)+ "\"}" fmt.Printf("Query Response:%s\n", jsonResp) return shim.Success(Avalbytes) } func main() { err := shim.Start(new(SimpleChaincode)) if err != nil { fmt.Printf("Error starting Simple chaincode: %s", err) } }
The same chaincode file is also deployed on the BYFN CLI container:
$ docker exec -it cli bash bash-4.4# echo $GOPATH /opt/gopath bash-4.4# ls -l $GOPATH/src/github.com/chaincode/chaincode_example02/go\ /chaincode_example02.go -rw-rw-r-- 1 1000 1000 5436 Feb 21 23:01 /opt/gopath/src/github.com/chaincode\ /chaincode_example02/go/chaincode_example02.go
⇒ Install Chaincode on BYFN Peers
⇐ Update Anchor Peer of Each BYFN Organization
2019-04-13, 1293🔥, 0💬
Popular Posts:
How to access Query String parameters from "context.Request.Url.Que ry"object in Azure API Policy? Q...
What is EPUB 2.0 Metadata "dc:identifier" Element? EPUB 2.0 Metadata "dc:identifier" is a required m...
Where to find EPUB Sample Files? Here is a list of EPUB sample files collected by FYIcenter.com team...
Why am I getting this "Docker failed to initialize" error? After installing the latest version of Do...
How to use "xml-to-json" Azure API Policy Statement? The "xml-to-json" Policy Statement allows you t...