Hyperledger Fabric 链码API的介绍

网址

https://godoc.org/github.com/hyperledger/fabric/core/chaincode/shim

参数读取API

• GetFunctionAndParameters 提取调用链码交易中的参数，其中第一个作为被调用的函数名称，剩下的参数作为函数的执行参数

func (stub *ChaincodeStub) GetFunctionAndParameters() (function string, params []string)

# {"Args":["set","tom","100"]}
fn, args := stub.GetFunctionAndParameters()
fmt.Println(fn, args)

# 输出结果
set ["tom", "100"]

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• GetStringArgs 提取链码交易的指定参数

func (stub *ChaincodeStub) GetStringArgs() []string

# {"Args":["set","tom","100"]}

args = stub.GetStringArgs()
fmt.Println(args)

# 输出结果
["set","tom","100"]

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账本状态交互API

• PutState 在账本中添加或更新一对键值。

func (stub *ChaincodeStub) PutState(key string, value []byte) error

err := stub.PutState("str",[]byte("hello"))
if err != nil {
fmt.Println("str PutState error: "+err.Error())
}else{
fmt.Println("str PutState success!")
}

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• GetState 负责查询账本，返回指定键的对应值

func (stub *ChaincodeStub) GetState(key string) ([]byte, error)

strValue , err := stub.GetState("str")
if err != nil {
fmt.Println("str GetState error: "+err.Error())
}else {
fmt.Printf("str value: %s \n",string(strValue))
}
# 输出结果
str value: hello

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• DelState 删除一对键值

func (stub *ChaincodeStub) DelState(key string) error

err = stub.DelState("str")

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• GetStateByRange 查询指定范围内的键值，startKey为起始key，endKey为终止key

func (stub *ChaincodeStub) GetStateByRange(startKey, endKey string) (StateQueryIteratorInterface, error)

err := stub.PutState("str",[]byte("hello"))
err = stub.PutState("str1",[]byte("hello1"))
err = stub.PutState("str2",[]byte("hello2"))
resultIterator , err := stub.GetStateByRange("str" , "str2")

defer resultIterator.Close()
fmt.Println("-----start resultIterator-----")
for resultIterator.HasNext() {
item, _ := resultIterator.Next()
fmt.Println(string(item.Value))
}
fmt.Println("-----end resultIterator-----")
# 运行结果
-----start resultIterator-----
hello
hello1
-----end resultIterator-----

---

• GetHistoryForKey 返回某个键的历史记录

func (stub *ChaincodeStub) GetHistoryForKey(key string) (HistoryQueryIteratorInterface, error)

historyIterator,err := stub.GetHistoryForKey("str")
defer historyIterator.Close()
fmt.Println("-----start historyIterator-----")
for resultIterator.HasNext() {
item, _ := historyIterator.Next()
fmt.Println(string(item.TxId))
fmt.Println(string(item.Value))
}
fmt.Println("-----end historyIterator-----")

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其他API

• CreateCompositeKey 给定一组属性，将这些属性组合起来构造一个复合键

func (stub *ChaincodeStub) CreateCompositeKey(objectType string, attributes []string) (string, error)

indexName := "sex~name"
indexKey , err := stub.CreateCompositeKey(indexName,[]string{"boy","xiaowang"})

value := []byte{0x00}
stub.PutState(indexKey,value)
fmt.Println(indexKey)
indexKey , err = stub.CreateCompositeKey(indexName,[]string{"boy","xiaoli"})
stub.PutState(indexKey,value)
fmt.Println(indexKey)
indexKey , err = stub.CreateCompositeKey(indexName,[]string{"girl","xiaofang"})
fmt.Println(indexKey)
stub.PutState(indexKey,value)
# 运行结果
sex~nameboyxiaowang
sex~nameboyxiaoli
sex~namegirlxiaofang

---

• SplitCompositeKey 给定一个复合键，将其拆分为复合键所用的属性

func (stub *ChaincodeStub) SplitCompositeKey(compositeKey string) (string, []string, error)

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• GetStateByPartialCompositeKey 根据局部的复合键返回所有的匹配的键值

func (stub *ChaincodeStub) GetStateByPartialCompositeKey(objectType string, attributes []string) (StateQueryIteratorInterface, error)

resultIterator,err = stub.GetStateByPartialCompositeKey(indexName, []string{"boy"})
defer resultIterator.Close()
fmt.Println("-----start resultIterator-----")
for resultIterator.HasNext() {
item, _ := resultIterator.Next()

objectType, compositeKeyParts, err := stub.SplitCompositeKey(item.Key)
if err != nil {
return shim.Error(err.Error())
}
fmt.Println("objectType: "+objectType)
fmt.Println("sex : "+compositeKeyParts[0])
fmt.Println("name : "+compositeKeyParts[1])
}
fmt.Println("-----end resultIterator-----")
# 运行结果
-----start resultIterator-----
objectType: sex~name
sex : boy
name : xiaoli
objectType: sex~name
sex : boy
name : xiaowang
-----end resultIterator----

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• GetQueryResult 对状态数据库进行富查询，仅有couchDB支持

func (stub *ChaincodeStub) GetQueryResult(query string) (StateQueryIteratorInterface, error)

resultIterator , err = stub.GetQueryResult("{\"selector\": {\"sex\": \"boy\"}}" )

defer resultIterator.Close()
fmt.Println("-----start resultIterator-----")
for resultIterator.HasNext() {
item, _ := resultIterator.Next()
fmt.Println(string(item.Value))
}
fmt.Println("-----end resultIterator-----")

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• InvokeChaincode 调用另一个链码中的Invoke方法

func (stub *ChaincodeStub) InvokeChaincode(chaincodeName string, args [][]byte, channel string) pb.Response

# chaincode_example02 中 a向b 转账
trans:=[][]byte{[]byte("invoke"),[]byte("a"),[]byte("b"),[]byte("11")}
stub.InvokeChaincode("mycc",trans,"mychannel")

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