github.com/kchristidis/fabric@v1.0.4-0.20171028114726-837acd08cde1/examples/chaincode/go/utxo/store.go (about)

     1  /*
     2  Copyright IBM Corp. 2016 All Rights Reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8  		 http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package main
    18  
    19  import (
    20  	"fmt"
    21  
    22  	"github.com/golang/protobuf/proto"
    23  	"github.com/hyperledger/fabric/core/chaincode/shim"
    24  	"github.com/hyperledger/fabric/examples/chaincode/go/utxo/util"
    25  )
    26  
    27  // Store struct uses a chaincode stub for state access
    28  type Store struct {
    29  	stub shim.ChaincodeStubInterface
    30  }
    31  
    32  // MakeChaincodeStore returns a store for storing keys in the state
    33  func MakeChaincodeStore(stub shim.ChaincodeStubInterface) util.Store {
    34  	store := &Store{}
    35  	store.stub = stub
    36  	return store
    37  }
    38  
    39  func keyToString(key *util.Key) string {
    40  	return key.TxHashAsHex + ":" + string(key.TxIndex)
    41  }
    42  
    43  // GetState returns the transaction for a given key
    44  func (s *Store) GetState(key util.Key) (*util.TX_TXOUT, bool, error) {
    45  	keyToFetch := keyToString(&key)
    46  	data, err := s.stub.GetState(keyToFetch)
    47  	if err != nil {
    48  		return nil, false, fmt.Errorf("Error getting state from stub:  %s", err)
    49  	}
    50  	if data == nil {
    51  		return nil, false, nil
    52  	}
    53  	// Value found, unmarshal
    54  	var value = &util.TX_TXOUT{}
    55  	err = proto.Unmarshal(data, value)
    56  	if err != nil {
    57  		return nil, false, fmt.Errorf("Error unmarshalling value:  %s", err)
    58  	}
    59  	return value, true, nil
    60  }
    61  
    62  // DelState deletes the transaction for the given key
    63  func (s *Store) DelState(key util.Key) error {
    64  	return s.stub.DelState(keyToString(&key))
    65  }
    66  
    67  // PutState stores the given transaction and key
    68  func (s *Store) PutState(key util.Key, value *util.TX_TXOUT) error {
    69  	data, err := proto.Marshal(value)
    70  	if err != nil {
    71  		return fmt.Errorf("Error marshalling value to bytes:  %s", err)
    72  	}
    73  	return s.stub.PutState(keyToString(&key), data)
    74  }
    75  
    76  // GetTran returns a transaction for the given hash
    77  func (s *Store) GetTran(key string) ([]byte, bool, error) {
    78  	data, err := s.stub.GetState(key)
    79  	if err != nil {
    80  		return nil, false, fmt.Errorf("Error getting state from stub:  %s", err)
    81  	}
    82  	if data == nil {
    83  		return nil, false, nil
    84  	}
    85  	return data, true, nil
    86  }
    87  
    88  // PutTran adds a transaction to the state with the hash as a key
    89  func (s *Store) PutTran(key string, value []byte) error {
    90  	return s.stub.PutState(key, value)
    91  }