Question

我的链码存在问题，因为我无法查询所有数据（过去的记录）并显示出来。

我希望做的是在键入相同的uniqueID变量时添加一个计数器。

使用计数器，添加唯一ID值，我可以得到正确的查询。

目前，当我运行此命令时，我可以从区块链中获取单个条目数据：

peer chaincode query -C food -n food_ccv01 -c '{"Args":["queryFoodInfo","1","123456789"]}'

使用"123456789"作为唯一ID和＆＃34; 1＆＃34;作为计数器，结合它们给了我一个独特的条目

但是我无法使用此＆＃34; 123456789＆＃34; +计数器来提取先前输入区块链的所有数据。

我怎么能这样做？还是有更好的方法？

我不知道为什么我的计数器无法初始化为整数，我现在正在使用字符串......

这是我的chaincode.

Answer 1

我认为您不需要使用计数器附加密钥，而是可以继续更新相同的密钥并查询所有更新，因为您可以使用以下API：

// GetHistoryForKey returns a history of key values across time.
// For each historic key update, the historic value and associated
// transaction id and timestamp are returned. The timestamp is the
// timestamp provided by the client in the proposal header.
// GetHistoryForKey requires peer configuration
// core.ledger.history.enableHistoryDatabase to be true.
// The query is NOT re-executed during validation phase, phantom reads are
// not detected. That is, other committed transactions may have updated
// the key concurrently, impacting the result set, and this would not be
// detected at validation/commit time. Applications susceptible to this
// should therefore not use GetHistoryForKey as part of transactions that
// update ledger, and should limit use to read-only chaincode operations.
GetHistoryForKey(key string) (HistoryQueryIteratorInterface, error)

E.g。这些方面的东西应该为你做一些工作：

func queryFoodFullInfo(stub shim.ChaincodeStubInterface, args []string) pb.Response {
    fmt.Println("Entering Query Food information")

    // Assuming food key is at zero index
    historyIer, err := stub.GetHistoryForKey(args[0])

    if err != nil {
        errMsg := fmt.Sprintf("[ERROR] cannot retrieve history of food record with id <%s>, due to %s", args[0], err)
        fmt.Println(errMsg)
        return shim.Error(errMsg)
    }

    result := make([]FavouritefoodInfo, 0)
    for historyIer.HasNext() {
        modification, err := historyIer.Next()
        if err != nil {
            errMsg := fmt.Sprintf("[ERROR] cannot read food record modification, id <%s>, due to %s", args[0], err)
            fmt.Println(errMsg)
            return shim.Error(errMsg)
        }
        var food FavouritefoodInfo
        json.Unmarshal(modification.Value, &food)
        result = append(result, food)
    }

    outputAsBytes, _ := json.Marshal(&result)                   
    return shim.Success(outputAsBytes)
 }

按照您的初始路径，您可能希望探索range query功能：

// GetStateByRange returns a range iterator over a set of keys in the
// ledger. The iterator can be used to iterate over all keys
// between the startKey (inclusive) and endKey (exclusive).
// The keys are returned by the iterator in lexical order. Note
// that startKey and endKey can be empty string, which implies unbounded range
// query on start or end.
// Call Close() on the returned StateQueryIteratorInterface object when done.
// The query is re-executed during validation phase to ensure result set
// has not changed since transaction endorsement (phantom reads detected).
GetStateByRange(startKey, endKey string) (StateQueryIteratorInterface, error)

请参阅marbles example。

无法使用Hyperledger fabric v1.0.0 chaincode查询所有历史记录/计数数据

1 个答案: