Blockchain By Example

The Query function

The final important function to define is the Query function. It is called when the application queries the Chaincode state. In our case Query definition is straightforward: we just need to pass a key—orderId—to get, in result, the corresponding food struct, as follows :

func (f *FoodContract) query(stub shim.ChaincodeStubInterface, args []string) pb.Response {                    var ENIITY string                    var err error                     if len(args) != 1 {                                         return shim.Error("Incorrect number of arguments. Expected ENIITY Name")                    }                     ENIITY = args[0]                    Avalbytes, err := stub.GetState(ENIITY)                    if err != nil {                                           sonResp := "{\"Error\":\"Failed to get state for " + ENIITY + "\"}"                                         return shim.Error(jsonResp)                    }                     if Avalbytes == nil {                                  jsonResp := "{\"Error\":\"Nil order ...