As its name indicates, the gethistory function reads a claim of all historical values records for a key, as well as the TxId and claim value.

We first define the AuditHistory struct, which has TxId and value. GetHistoryForKey returns the list of results with resultsIterator, which contains all historical transaction records. We iterate through these records and add them to an array of AuditHistory. Later, we convert it to JSON byte and send the data back as a response, as follows:

func (c *ClaimContract) getHistory(stub shim.ChaincodeStubInterface, args []string) pb.Response {
         type AuditHistory struct {
                 TxId  string `json:"txId"`
                 Value Claim  `json:"value"`
         }
         var history []AuditHistory
         var claim Claim
         if len(args) != 1 {
                 return shim.Error("Incorrect number of arguments. Expecting 1")
         }
         claimId := args[0]
         fmt.Printf("- start getHistoryForClaim: %s
", claimId)


         // Get History
         resultsIterator, err := stub.GetHistoryForKey(claimId)
         if err != nil {
                 return shim.Error(err.Error())
         }
         defer resultsIterator.Close()


         for resultsIterator.HasNext() {
                 historyData, err := resultsIterator.Next()
                 if err != nil {
                          return shim.Error(err.Error())
                 }
                 var tx AuditHistory
                 tx.TxId = historyData.TxId
                 json.Unmarshal(historyData.Value, &claim)
                 tx.Value = claim              //copy claim over
                 history = append(history, tx) //add this tx to the list
         }
         fmt.Printf("- getHistoryForClaim returning:
%s", history)


         //change to array of bytes
         historyAsBytes, _ := json.Marshal(history) //convert to array of bytes
         return shim.Success(historyAsBytes)
}

This covers our issuance claim chaincode. We will learn about Hyperledger Fabric configuration in the next section.