六、编写第一个应用【外部nodejs调用】

一、

参考地址：https://hyperledger-fabric.readthedocs.io/en/latest/write_first_app.html

根据前几节的配置

1、下载代码

git clone https://github.com/hyperledger/fabric-samples.git
cd fabric-samples/fabcar

2、在fabcar下会有如下文件

chaincode    invoke.js       network         package.json    query.js        startFabric.sh

新版本的示例，chaincode在根目录下

3、开启网络配置[注意docker版本17.06,在1.12.6版本没有-e命令]

./startFabric.sh

4、查询一个账本

安装node

yum install gcc-c++
npm install

查询[注意配置query.js中的ip地址]

node query.js

展示如下数据

Create a client and set the wallet location
Set wallet path, and associate user  PeerAdmin  with application
Check user is enrolled, and set a query URL in the network
Make query
Assigning transaction_id:  f2f45cb045d6290d199e1b2d4eb3b60b1e9cafeff8d09e2b7683dd8578492be7
returned from query
Query result count =  1
Response is  [{"Key":"CAR0", "Record":{"colour":"blue","make":"Toyota","model":"Prius","owner":"Tomoko"}},{"Key":"CAR1", "Record":{"colour":"red","make":"Ford","model":"Mustang","owner":"Brad"}},{"Key":"CAR2", "Record":{"colour":"green","make":"Hyundai","model":"Tucson","owner":"Jin Soo"}},{"Key":"CAR3", "Record":{"colour":"yellow","make":"Volkswagen","model":"Passat","owner":"Max"}},{"Key":"CAR4", "Record":{"colour":"black","make":"Tesla","model":"S","owner":"Adriana"}},{"Key":"CAR5", "Record":{"colour":"purple","make":"Peugeot","model":"205","owner":"Michel"}},{"Key":"CAR6", "Record":{"colour":"white","make":"Chery","model":"S22L","owner":"Aarav"}},{"Key":"CAR7", "Record":{"colour":"violet","make":"Fiat","model":"Punto","owner":"Pari"}},{"Key":"CAR8", "Record":{"colour":"indigo","make":"Tata","model":"Nano","owner":"Valeria"}},{"Key":"CAR9", "Record":{"colour":"brown","make":"Holden","model":"Barina","owner":"Shotaro"}}]

5、分析query.js

1》初始化参数，包含了用户ID，信道，链码，网络连接入口

var options = {
    wallet_path: path.join(__dirname, './creds'),
    user_id: 'PeerAdmin',
    channel_id: 'mychannel',
    chaincode_id: 'fabcar',
    network_url: 'grpc://localhost:7051',
};

2》查询代码

    var transaction_id = client.newTransactionID();

    // queryCar - requires 1 argument, ex: args: ['CAR4'],
    // queryAllCars - requires no arguments , ex: args: [''],
    const request = {
        chaincodeId: options.chaincode_id,
        txId: transaction_id,
        fcn: 'queryAllCars',
        args: ['']
    };
    return channel.queryByChaincode(request);

这里设置了链码ID，交易ID，以及调用的链码的方法fcn，方法参数args等

3》链码：/chaincode/fabcar/目录下fabcar.go

此文件匹配上文的链码ID，包含了如下方法：initLedger, queryCar,queryAllCars, createCar and changeCarOwner

func (s *SmartContract) queryAllCars(APIstub shim.ChaincodeStubInterface) sc.Response {
    startKey := "CAR0"
    endKey := "CAR999"

    resultsIterator, err := APIstub.GetStateByRange(startKey, endKey)

此处就是查询范围内的数据。

查看所有方法

6、测试

cp query.js query1.js
vim query1.js

修改内部访问链码方法

    const request = {
        chaincodeId: options.chaincode_id,
        txId: transaction_id,
        fcn: 'queryCar',
        args: ['CAR4']
    };

执行：node query1.js

Create a client and set the wallet location
Set wallet path, and associate user  PeerAdmin  with application
Check user is enrolled, and set a query URL in the network
Make query
Assigning transaction_id:  ca88dc3b60f4df009a709f2f5ee5ad3b54f43d03a7e0b931042e2797f70c795d
returned from query
Query result count =  1
Response is  {"colour":"black","make":"Tesla","model":"S","owner":"Adriana"}

7、更新账本数据

使用fabcar目录下的invoke.js

修改，中的 fcn，以及args等参数

var request = {
    targets: targets,
    chaincodeId: options.chaincode_id,
    fcn: '',
    args: [''],
    chainId: options.channel_id,
    txId: tx_id

如下

var request = {
    targets: targets,
    chaincodeId: options.chaincode_id,
    fcn: 'createCar',
    args: ['CAR10', 'Chevy', 'Volt', 'Red', 'Nick'],
    chainId: options.channel_id,
    txId: tx_id

执行命令

node invoke.js

成功后会有

The transaction has been committed on peer localhost:7053

执行

cp query1.js query2.js
vim query2.js

将query2.js中查询条件参数，变为CAR10即可

Response is  {"colour":"Red","make":"Chevy","model":"Volt","owner":"Nick"}

ok，可以继续调试其他方法。