// Query has two functions
// get - takes one argument, a key, and returns the value for the key
// keys - returns all keys stored in this chaincode
func (t *SimpleChaincode) Query(stub shim.ChaincodeStubInterface, function string, args []string) ([]byte, error) {
switch function {
case "get":
if len(args) < 1 {
return nil, errors.New("get operation must include one argument, a key")
}
key := args[0]
value, err := stub.GetState(key)
if err != nil {
return nil, fmt.Errorf("get operation failed. Error accessing state: %s", err)
}
return value, nil
case "keys":
keysIter, err := stub.RangeQueryState("", "")
if err != nil {
return nil, fmt.Errorf("keys operation failed. Error accessing state: %s", err)
}
defer keysIter.Close()
var keys []string
for keysIter.HasNext() {
key, _, iterErr := keysIter.Next()
if iterErr != nil {
return nil, fmt.Errorf("keys operation failed. Error accessing state: %s", err)
}
keys = append(keys, key)
}
jsonKeys, err := json.Marshal(keys)
if err != nil {
return nil, fmt.Errorf("keys operation failed. Error marshaling JSON: %s", err)
}
return jsonKeys, nil
default:
return nil, errors.New("Unsupported operation")
}
}
// Invoke has two functions
// put - takes two arguements, a key and value, and stores them in the state
// remove - takes one argument, a key, and removes if from the state
func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) ([]byte, error) {
function, args := stub.GetFunctionAndParameters()
switch function {
case "put":
if len(args) < 2 {
return nil, errors.New("put operation must include two arguments, a key and value")
}
key := args[0]
value := args[1]
err := stub.PutState(key, []byte(value))
if err != nil {
fmt.Printf("Error putting state %s", err)
return nil, fmt.Errorf("put operation failed. Error updating state: %s", err)
}
return nil, nil
case "remove":
if len(args) < 1 {
return nil, errors.New("remove operation must include one argument, a key")
}
key := args[0]
err := stub.DelState(key)
if err != nil {
return nil, fmt.Errorf("remove operation failed. Error updating state: %s", err)
}
return nil, nil
case "get":
if len(args) < 1 {
return nil, errors.New("get operation must include one argument, a key")
}
key := args[0]
value, err := stub.GetState(key)
if err != nil {
return nil, fmt.Errorf("get operation failed. Error accessing state: %s", err)
}
return value, nil
case "keys":
keysIter, err := stub.RangeQueryState("", "")
if err != nil {
return nil, fmt.Errorf("keys operation failed. Error accessing state: %s", err)
}
defer keysIter.Close()
var keys []string
for keysIter.HasNext() {
key, _, iterErr := keysIter.Next()
if iterErr != nil {
return nil, fmt.Errorf("keys operation failed. Error accessing state: %s", err)
}
keys = append(keys, key)
}
jsonKeys, err := json.Marshal(keys)
if err != nil {
return nil, fmt.Errorf("keys operation failed. Error marshaling JSON: %s", err)
}
return jsonKeys, nil
default:
return nil, errors.New("Unsupported operation")
}
}