Question

我一直在开发一个涉及前端调用区块链链码的应用程序。

Chaincode为发送的所有事务返回OK消息。即使失败的交易也可以作为回复。虽然可以在区块链日志中看到错误。

有没有办法让链码一直发送错误信息回到前端，以防错误发生，以便前端知道交易是否成功？

Answer 1

Chaincode应符合以下API：

// Chaincode interface must be implemented by all chaincodes. The fabric runs
// the transactions by calling these functions as specified.
type Chaincode interface {
    // Init is called during Instantiate transaction after the chaincode container
    // has been established for the first time, allowing the chaincode to
    // initialize its internal data
    Init(stub ChaincodeStubInterface) pb.Response

    // Invoke is called to update or query the ledger in a proposal transaction.
    // Updated state variables are not committed to the ledger until the
    // transaction is committed.
    Invoke(stub ChaincodeStubInterface) pb.Response
}

pb.Response的位置：

// A response with a representation similar to an HTTP response that can
// be used within another message.
type Response struct {
    // A status code that should follow the HTTP status codes.
    Status int32 `protobuf:"varint,1,opt,name=status" json:"status,omitempty"`
    // A message associated with the response code.
    Message string `protobuf:"bytes,2,opt,name=message" json:"message,omitempty"`
    // A payload that can be used to include metadata with this response.
    Payload []byte `protobuf:"bytes,3,opt,name=payload,proto3" json:"payload,omitempty"`
}

Chaincode shim提供Facade函数来返回response.go中定义的错误和成功状态。因此，在您的链代码上实现流程时，您可以使用不同的响应类型来发送信号并将错误转发回客户端，example：

func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
    fmt.Println("ex02 Invoke")
    function, args := stub.GetFunctionAndParameters()
    if function == "invoke" {
        // Make payment of X units from A to B
        return t.invoke(stub, args)
    } else if function == "delete" {
        // Deletes an entity from its state
        return t.delete(stub, args)
    } else if function == "query" {
        // the old "Query" is now implemtned in invoke
        return t.query(stub, args)
    }

    return shim.Error("Invalid invoke function name. Expecting \"invoke\" \"delete\" \"query\"")
}

如果您尝试调用设置了错误参数的链码，则会回复错误。稍后您可以检查响应以查看是否发生错误或者没有发生错误，您也可以使用消息扩展您的响应，以提供有关所发生情况的更多详细信息。

链码如何将错误消息发送回呼叫来自的应用程序？

1 个答案: