BCSkill (Block chain skill )
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基于EOS的Dapp就是html页面通过调用eosjs与EOS链进行RPC通信，进行合约执行与数据交换。

下面演示Hello合约的Dapp调用
合约源代码
//hello.cpp

#include <eosiolib/eosio.hpp>
using namespace eosio;

class hello : public eosio::contract {
  public:
      using contract::contract;

      /// @abi action 
      void hi( account_name user ) {
         print( "Hello, ", name{user} );
      }
};

EOSIO_ABI( hello, (hi) )

合约部署参考（零基础部署测试合约（三）---合约部署）

html 调用js关键代码

import EOS from 'eosjs'
const EOS_CONFIG = {
  contractName: "dapp.token", // Contract name
  contractReceiver: "dapp.exec", // User executing the contract (should be paired with private key)
  clientConfig: {
    keyProvider: '5JC9FdRjX3c3fsB62S5Tz22LgTuRHegb1XEV16uft8u3njmm9E5', // Your private key
    httpEndpoint: 'http://192.168.1.112:8888', // EOS http endpoint
    chainId: '706a7ddd808de9fc2b8879904f3b392256c83104c1d544b38302cc07d9fca477'
  }
}
//执行合约
DoContract(){
let eosClient = EOS(EOS_CONFIG.clientConfig)
    eosClient.contract(EOS_CONFIG.contractName)
      .then((contract) => {
        contract.hi(EOS_CONFIG.contractReceiver, { authorization: [EOS_CONFIG.contractReceiver] })
          .then((res) => { console.log("Success") })
          .catch((err) => {console.log("Fail"); console.log(err) })
      })
}

从前一篇文章讲解了EOS账户权限介绍以及增删改查
下面介绍下账户权限的使用
基于上篇第5步（为bcskill账号增加自定义权限组custom，基于active ）开始进行

1.首先先给账号bcskill转点SYS代币

发币步骤请参考（零基础EOS 节点部署，BP出块（三）-->开始部署），这里就不多做介绍

cleos push action eosio.token transfer '["eosio", "bcskill","1000.0000 SYS","bcskill"]' -p eosio

2.查询bcskill账户余额

cleos get currency balance eosio.token bcskill

3.用bcskill账号已custom权限转账给eosio

cleos push action eosio.token transfer '["bcskill", "eosio","100.0000 SYS","bcskill"]' -p bcskill@custom

4.custom权限组绑定transfer action

cleos set action permission bcskill eosio.token transfer custom

5.用bcskill账号已custom权限转账给eosio

cleos push action eosio.token transfer '["bcskill", "eosio","100.0000 SYS","bcskill"]' -p bcskill@custom

6.查询bcskill账户余额

cleos get currency balance eosio.token bcskill

经过两篇文章我们可以看出EOS的权限管理非常灵活。

EOS一直宣传自己的账号权限机制，下面将演示针对账号bcskill三个权限组的增删改查

• owner 账号拥有者，拥有账号全部的权限，等于超级管理员 （新建账号预设）
• active 拥有账号大部分账户的权限，等于管理员 （新建账号预设）
• custom 自定义添加，用于下面演示针对权限组的增删改查

  拥有哪些组的私钥，就拥有当前账号哪些权限。每个组可以有多个授权key，也可以多个授权账户。

1. 生成多组公钥私钥 （在线生成）

• 用于添加到三个权限组演示

• 用于演示一个权限组多个账号

• 用于演示一个权限组多个授权key

2.导入私钥

cleos wallet import 5Hvpv1qkoBymEb8DA1MfrgHdcPbxGkE7Ux9DPzhRnb8kHBoAuBn
cleos wallet import 5Jqq6ztSk41Y6duygrFwCKKVBTaat8zLExG3owwnJSHZMKRcZC4
cleos wallet import 5JewRAyyYoNoTfwmy32CLBiyqS2DfQ8njY4ENuzqJ5Rrp7Zft2o

3.创建账号

cleos system newaccount eosio bcskill EOS6fQzsc9Bn5buFbNxHgGMNh9zr2gcbHz2YaaBCfMApw3E8vADu3 EOS5G45ChvRSTjQJGvHX8gBEV2ZrUvbxnh6WEd1qfXKox7KqnZb7j  --stake-net '50.00 SYS' --stake-cpu '50.00 SYS' --buy-ram-kbytes 10000

创建账户时，会一同加入owner，active两个组，（两个组的公钥可以用同一个，但不建议）

4.查看账户信息

cleos get account bcskill -j

也就是只要有EOS6fQzsc9Bn5buFbNxHgGMNh9zr2gcbHz2YaaBCfMApw3E8vADu3的私钥，就拥有对账户bcskill的owner权限组的权限

拥有EOS5G45ChvRSTjQJGvHX8gBEV2ZrUvbxnh6WEd1qfXKox7KqnZb7j的私钥，就拥有对账户bcskill的active权限组的权限

5.为bcskill账号增加自定义权限组custom，基于active

cleos set account permission bcskill custom '{"threshold":1,"keys":[{"key":"EOS5QxpwkWLAAWQqcT8teKrUceYr5Nj6PsBmCVoLaQQVqcoP2ZjF5","weight":1}],"accounts":[]}' active

6.查看账户信息

cleos get account bcskill -j

7.为权限组custom更换权限key

cleos set account permission bcskill custom '{"threshold": 1, "keys": [{"key": "EOS7UKzLPHVUTYpex48pRZokvBNEEp5KKXFGwcb5Qv6dZTWUYHGeP", "weight": 1}], "accounts": []}' active

8.查看账户信息

cleos get account bcskill -j

custom授权key已更新

9.为custom添加多个授权key

cleos set account permission bcskill custom '{"threshold":1,"keys":[{"key":"EOS5QxpwkWLAAWQqcT8teKrUceYr5Nj6PsBmCVoLaQQVqcoP2ZjF5","weight":1},{"key":"EOS7UKzLPHVUTYpex48pRZokvBNEEp5KKXFGwcb5Qv6dZTWUYHGeP","weight":1}],"accounts":[]}' active

10.查看账户信息

cleos get account bcskill -j

custom已有两个授权key

11.创建账号temporary

cleos system newaccount eosio temporary EOS7Yfs4kL6j9G8nmCTFt5ycLUpV4NmPaZKfuVfYC8XJbuDYPPdnA EOS7Yfs4kL6j9G8nmCTFt5ycLUpV4NmPaZKfuVfYC8XJbuDYPPdnA  --stake-net '50.00 SYS' --stake-cpu '50.00 SYS' --buy-ram-kbytes 10000

12.为custom添加其他授权账号temporary

cleos set account permission bcskill custom '{"threshold":2,"keys":[{"key":"EOS5QxpwkWLAAWQqcT8teKrUceYr5Nj6PsBmCVoLaQQVqcoP2ZjF5","weight":1}],"accounts":[{"permission":{"actor":"temporary","permission":"active"},"weight":1}]}' active

13.查看账户信息

cleos get account bcskill -j

custom已有授权账号temporary

14.删除custom权限组

cleos set account permission bcskill custom 'NULL' active

15.查看账户信息

cleos get account bcskill -j

custom权限组已被删除

下一篇将讲解EOS账户权限的使用

下面开始编译合约

进入合约目录 /License

1. 生成ABI

   eosiocpp -g License.abi License.cpp

2. 生成WAST

   eosiocpp -o License.wast License.cpp

   执行完成后
   

开始部署合约

在部署测试合约（一）---前准备中，已经创建dapp.token,dapp.exec账号

下面开始在dapp.token账户部署合约

cleos set contract dapp.token License/ -p dapp.token

开始执行合约

1. 执行合约setuserinfo 修改用户信息

   cleos push action dapp.token setuserinfo '["dapp.exec","区块链技能学习", "bcskill.com"]' -p dapp.exec

   

2. 查看用户信息

   cleos get table dapp.token dapp.token accounts

   

3. 执行合约makeproject 创建项目

   cleos push action dapp.token makeproject '["dapp.exec","testcontract"]' -p dapp.exec

   

4. 查看项目信息

   cleos get table dapp.token dapp.token projecttable

   

5. 执行合约 buylicense购买项目授权

   cleos push action dapp.token buylicense '["dapp.exec","testcontract"]' -p dapp.exec

   

6. 查看项目信息

   cleos get table dapp.token dapp.token projecttable

   

下面演示EOS智能合约编写，实例将涉及对链上多索引（multi_index）的增删改查。

实例为License合约，主要功能为

• 客户设置自己的信息
• 客户创建自己的项目
• 客户购买项目授权
• 验证项目授权
  （由于演示二级索引，项目名称为索引唯一，所以实例为用户单项目）
  上面的权限都是基于客户自身的权限验证，创建是创建的系统子账户，可用于系统币转账

合约代码基于C++语言，源代码分为源文件（.cpp）和头文件(.hpp)
//License.hpp

#include <eosiolib/asset.hpp>
#include <eosiolib/eosio.hpp>
#include <eosiolib/print.hpp>

class License : public eosio::contract {
    public:
        License( account_name self )
        :eosio::contract(self)
        ,accounts(_self, _self)
        ,projecttable(_self, _self){}

        void setuserinfo(account_name owner, const std::string& company_name, const std::string& contact_info);
        void makeproject(account_name owner, const std::string& project_name);
        void buylicense(account_name owner, const std::string& project_name);
        void testlicense(account_name owner, const std::string& project_name);

    private:
        //@abi table accounts i64
        struct account{
            account_name name;
            std::string company_name;
            std::string contact_info;
            uint8_t level;
            uint64_t primary_key()const { return name; }
            EOSLIB_SERIALIZE(account, (name)(company_name)(contact_info)(level))
        };

        typedef eosio::multi_index<N(accounts),account> account_table;
        account_table accounts;

        //@abi table projecttable i64
        struct project{
            uint32_t pkey;
            account_name owner_name;
            std::string project_name;
            std::string company_name;
            std::string contact_info;
            uint8_t      status;

            uint64_t primary_key()const { return pkey; }
            uint64_t getowner_name() const{return owner_name;}
            EOSLIB_SERIALIZE(project, (pkey)(owner_name)(project_name)(company_name)(contact_info)(status))
        };
        //contracts/eosiolib/multi_index.hpp
        //multi_index用于封装智能合约对数据库的管理，增、删、改、查
        //eosio::multi_index<N(表名),数据类型> 
        //一个multi_index最多支持16个二级索引
        //定义二级索引使用eosio::indexed_by模板。N(byowner_name)为索引的名称
        //project表数据类型，uint64_t索引类型即索引函数返回的类型(只支持uint64_t,uint128_t,double,long double,key256类型)，&project::getowner_name索引函数。
        typedef eosio::multi_index<N(projecttable),project, eosio::indexed_by<N(byowner_name), eosio::const_mem_fun<project, account_name, &project::getowner_name> >> projecttable_type;
        projecttable_type projecttable;
};
EOSIO_ABI(License, (setuserinfo)(makeproject)(buylicense)(testlicense))

//License.cpp

#include <License.hpp>

void License::setuserinfo(account_name owner, const std::string& company_name, const std::string& contact_info){
    eosio::print("License::setuserinfo line 4");
    require_auth(owner);
    auto account_itr = accounts.find(owner);
    if(account_itr == accounts.end()){
        account_itr = accounts.emplace(_self, [&](auto& account){
            account.name = owner;
            account.company_name = company_name;
            account.contact_info = contact_info;
        });
    }
    else{
        accounts.modify(account_itr, 0, [&](auto& account) {
            account.company_name = company_name;
            account.contact_info = contact_info;
        });
    }
}

void License::makeproject(account_name owner, const std::string& project_name){
    require_auth(owner);
    //二级索引查找
    auto customer_index = projecttable.template get_index<N(byowner_name)>();
    account_name customer_acct = owner; //如果是string 可以用 eosio::string_to_name 转换
    auto cust_itr = customer_index.find(customer_acct);
    if (cust_itr != customer_index.end() && cust_itr->owner_name == customer_acct) {
        customer_index.modify(cust_itr, 0, [&](auto& project) {
            project.project_name = project_name;
            project.status = cust_itr->status; //初始化未授权，须另购买
            auto account_itr = accounts.find(owner);
            if(account_itr != accounts.end()){
                project.project_name = project_name;
                project.company_name = account_itr->company_name;
                project.contact_info = account_itr->contact_info;

            }
        });
    } 
    else{
        auto project_itr = projecttable.emplace(_self, [&](auto& project){
                project.owner_name = owner;
                project.project_name = project_name;
                auto account_itr = accounts.find(owner);
                if(account_itr != accounts.end()){
                    project.company_name = account_itr->company_name;
                    project.contact_info = account_itr->contact_info;
                    project.status = 0; //初始化未授权，须另购买
                }
            });
    }
}

void License::buylicense(account_name owner, const std::string& project_name){
    require_auth(owner);
    bool bFind = false;
    //二级索引查找
    auto customer_index = projecttable.template get_index<N(byowner_name)>();
    account_name customer_acct = owner; //如果是string 可以用 eosio::string_to_name 转换
    auto cust_itr = customer_index.find(customer_acct);
    while (cust_itr != customer_index.end() && cust_itr->owner_name == customer_acct) {
        if(cust_itr->project_name == project_name){
            if(cust_itr->status == 0){
                //TODO 判断当前账户余额，购买转账等操作
                customer_index.modify(cust_itr, 0, [&](auto& project) {
                    project.status = 1;
                });
            }
            else{
                eosio_assert(false, "The current project is authorized" );
            }
            bFind = true;
            break;
        }
        cust_itr++;
    } 
    eosio_assert(bFind, "owner with project not exists" );
}

void License::testlicense(account_name owner, const std::string& project_name){
    require_auth(owner);
    bool bFind = false;
    for( const auto& project : projecttable ) {
        if(project.project_name == project_name && project.owner_name == owner){
            eosio_assert((project.status == 1), "The current project is not authorized" );
            bFind = true;
            break;
        }
    }
    eosio_assert(bFind, "owner with project not exists" );
}

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