I am trying to write chaincode for Hyperledger that has a mapping, that stores struct values mapped to strings. This is my first time writing contracts for Hyperledger and also my first time using go and it appears I am not approaching this the right way.
This is my mapping, Data struct, Init function and addVData function that shows the problem.
type Data struct{
Timestamp string
Velocity string
Location string
}
var all_data map[string]Data
func (t *DataContract) Init(stub shim.ChaincodeStubInterface) peer.Response {
all_data = make(map[string]Data)
return shim.Success(nil)
}
func (t *DataContract) addVData(stub shim.ChaincodeStubInterface, args []string) peer.Response {
params := stub.GetStringArgs()
fmt.Println("The params passed in are:", params)
if len(params) != 4 {
fmt.Println("Please resubmit in this particular order: addVData, Timestamp, Velocity, Location")
return shim.Error("Please resubmit in this particular order: addVData, Timestamp, Velocity, Location")
}
var d = Data{Timestamp:params[1], Velocity:params[2], Location:params[3]}
all_data[params[1]] = d
var err = stub.PutState(params[1],d)
return shim.Success(nil)
}
The error I am getting is actually very clear:
./data.go:79:35: cannot use d (type Data) as type []byte in argument to stub.PutState
I am wondering, since my data is not in form of a byte array, how do I go about storing it? Also, I am not certain I have implemented the Init method and the mappings in the correct way but have had a hard time finding examples. If you could please explain and point me in the right direction it would be very appreciated, thank you.
Use
json.Marshal
function to convert thestruct
intobytes