How to fetch asset modification history in hyperledger fabric

Question

I am using IBM bluemix blockchain service to tryout some smart contract logic for my asset sharing demo.

Is there anyway to query the asset modified history in hyp

Answer 1

IF you need. Java SDk and go chaincode combination. Here is the example

Java code

public List getUFOHistory(String key) throws Exception {
    String[] args = { key };
    Logger.getLogger(QueryChaincode.class.getName()).log(Level.INFO, "UFO communication history - " + args[0]);

    Collection responses1Query = ucc.getChannelClient().queryByChainCode("skynetchaincode", "getHistoryForUFO", args);
    String stringResponse = null;
    ArrayList newArrayList = new ArrayList<>();
    for (ProposalResponse pres : responses1Query) {
        stringResponse = new String(pres.getChaincodeActionResponsePayload());
        Logger.getLogger(QueryChaincode.class.getName()).log(Level.INFO, stringResponse);
        newArrayList = gson.fromJson(stringResponse, new TypeToken>() {
        }.getType());
    }
    if (null == stringResponse)
        stringResponse = "Not able to find any ufo communication history";
    return newArrayList;
}

and you go chancode implemetation is as follows

Go code

func (t *SmartContract) getHistoryForUFO(APIstub shim.ChaincodeStubInterface, args []string) sc.Response {

    if len(args) < 1 {
            return shim.Error("Incorrect number of arguments. Expecting 1")
    }

    ufoId := args[0]
    resultsIterator, err := APIstub.GetHistoryForKey(ufoId)
    if err != nil {
            return shim.Error(err.Error())
    }
    defer resultsIterator.Close()

    var buffer bytes.Buffer
    buffer.WriteString("[")

    bArrayMemberAlreadyWritten := false
    for resultsIterator.HasNext() {
            response, err := resultsIterator.Next()
            if err != nil {
                    return shim.Error(err.Error())
            }
            // Add a comma before array members, suppress it for the first array member
            if bArrayMemberAlreadyWritten == true {
                    buffer.WriteString(",")
            }
            buffer.WriteString("{\"TxId\":")
            buffer.WriteString("\"")
            buffer.WriteString(response.TxId)
            buffer.WriteString("\"")

            buffer.WriteString(", \"Value\":")
            // if it was a delete operation on given key, then we need to set the
            //corresponding value null. Else, we will write the response.Value
            //as-is (as the Value itself a JSON)
            if response.IsDelete {
                    buffer.WriteString("null")
            } else {
                    buffer.WriteString(string(response.Value))
            }

            buffer.WriteString(", \"Timestamp\":")
            buffer.WriteString("\"")
            buffer.WriteString(time.Unix(response.Timestamp.Seconds, int64(response.Timestamp.Nanos)).String())
            buffer.WriteString("\"")

            buffer.WriteString(", \"IsDelete\":")
            buffer.WriteString("\"")
            buffer.WriteString(strconv.FormatBool(response.IsDelete))
            buffer.WriteString("\"")

            buffer.WriteString("}")
            bArrayMemberAlreadyWritten = true
    }
    buffer.WriteString("]")

    fmt.Printf("- History returning:\n%s\n", buffer.String())
    return shim.Success(buffer.Bytes())
}

There you go. Have fun.