上QQ阅读APP看书，第一时间看更新

The Invoke function

The implementation of the Invoke function is as follows:

func (c *AssetMgr) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
               function, args := stub.GetFunctionAndParameters()
               if function == "Order" {
                               return c.Order(stub, args)
               } else if function == "Ship" {
                               return c.Ship(stub, args)
               } else if function == "Distribute" {
                               return c.Distribute(stub, args)
               } else if function == "query" {
                               return c.query(stub, args)
               } else if function == "getHistory" {
                               return c.getHistory(stub, args)
               }
               return shim.Error("Invalid function name")
}

The Order, Ship, and Distribute functions will be quite similar. These will update the ledger state. We will use order() as an example to show how we implement the chaincode function:

func (c *AssetMgr) Order(stub shim.ChaincodeStubInterface, args []string) pb.Response {
               return c.UpdateAsset(stub, args, "ORDER", "SCHOOL", "OEM")
}

Here is the UpdateAsset function:

func (c *AssetMgr) UpdateAsset(stub shim.ChaincodeStubInterface, args []string, currentStatus string, from string, to string) pb.Response {
               assetId := args[0]   comment := args[1]               location := args[2]
               assetBytes, err := stub.GetState(assetId)
               orgAsset := OrgAsset{}
               …
               if currentStatus == "ORDER" && orgAsset.Status != "START" {
               return shim.Error(err.Error())
               } else if currentStatus == "SHIP" && orgAsset.Status != "ORDER" {.}
else if currentStatus == "DISTRIBUTE" && orgAsset.Status != "SHIP" {.}
               orgAsset.Comment = comment
               orgAsset.Status = currentStatus
….
               orgAsset0, _ := json.Marshal(orgAsset)
               err = stub.PutState(assetId, orgAsset0)
               …
               return shim.Success(orgAsset0)
}