EOS智能合约-增删改查

#include <eosiolib/eosio.hpp>

class [[eosio::contract]] testcontract : public eosio::contract
{
public:
    testcontract( eosio::name receiver, eosio::name code, eosio::datastream<const char*> ds )
        : eosio::contract(receiver, code, ds),  _students(receiver, code.value)
    {}

    //添加学生
    [[eosio::action]]
    void add(eosio::name user, std::string studentName,std::string studentGender,uint32_t studentAge,uint32_t studentHeight)
    {
        require_auth(user);
        eosio::print("Add student ", studentName);
        _students.emplace(get_self(), [&](auto& p) {
            p.id = _students.available_primary_key();
            p.studentName = studentName;
            p.studentGender = studentGender;
            p.studentAge = studentAge;
            p.studentHeight = studentHeight;
        });
    }

    //根据主键删除学生
    [[eosio::action]]
    void del(eosio::name user, uint64_t id)
    {
        require_auth(user);
        eosio::print("Del student", id);
        auto itr = _students.find(id);
        if (itr != _students.end()) {
            _students.erase(itr);
        }
    }

    //根据主键修改学生
    [[eosio::action]]
    void update(eosio::name user, uint64_t id,std::string studentName,std::string studentGender,uint32_t studentAge,uint32_t studentHeight)
    {
        require_auth(user);
        eosio::print("update student", studentName);
        auto itr = _students.find(id);
        if (itr != _students.end())
        {
            _students.modify(itr, user, [&]( auto& p ) {
                p.studentName = studentName;
                p.studentGender = studentGender;
                p.studentAge = studentAge;
                p.studentHeight = studentHeight;
            });
        }
    }

    //清空表,待定
    [[eosio::action]]
    void clear(eosio::name user)
    {
        require_auth(user);
        std::vector<uint64_t> keysForDeletion;
        for(auto& item : _students) {
            keysForDeletion.push_back(item.id);
        }

        for (uint64_t key : keysForDeletion) {
            eosio::print("remove from _students ", key);
            auto itr = _students.find(key);
            if (itr != _students.end()) {
                _students.erase(itr);
            }
        }
    }

    //private: -- not private so the cleos get table call can see the table data.
    // create the multi index tables to store the data
    struct [[eosio::table]] students
    {
        uint64_t      id; // primary key
        std::string   studentName;
        std::string   studentGender;
        uint32_t    studentAge;
        uint32_t    studentHeight;

        uint64_t primary_key() const { return id; }
        uint64_t by_age() const {return studentAge; }
    };

    //数据表根据age排序
    typedef eosio::multi_index<"students"_n, students, eosio::indexed_by<"studentage"_n, eosio::const_mem_fun<students, uint64_t, &students::by_age>>> studentstable;

    //students数据库表
    studentstable _students;
};

EOSIO_DISPATCH( testcontract, (add)(del)(update)(clear))

1.编译与部署合约
xjdeMacBook-Pro:testcontract xj$ eosio-cpp -o testcontract.wasm testcontract.cpp --abigen
Warning, empty ricardian clause file
Warning, empty ricardian clause file
Warning, action <add> does not have a ricardian contract
Warning, action <del> does not have a ricardian contract
Warning, action <update> does not have a ricardian contract
Warning, action <clear> does not have a ricardian contract
(reverse-i-search)`':
xjdeMacBook-Pro:testcontract xj$ cleos set contract testcontract /Users/xj/code/eos/build/programs/cleos/testcontract -p testcontract@active
Reading WASM from /Users/xj/code/eos/build/programs/cleos/testcontract/testcontract.wasm...
Skipping set code because the new code is the same as the existing code
Skipping set abi because the new abi is the same as the existing abi
no transaction is sent

2.添加数据
xjdeMacBook-Pro:testcontract xj$ cleos push action testcontract add '["testcontract","wangwu","male",11,120]' -p eosio@active
executed transaction: 4ea9886d0347e75028ef5f4d2180ceee2f5a8843783f30ee7fb3a473b3dc2039  120 bytes  1308 us
#  testcontract <= testcontract::add            {"s":"testcontract","studentName":"wangwu","studentGender":"male","studentAge":11,"studentHeight":12...
warning: transaction executed locally, but may not be confirmed by the network yet         ]

3.查询
xjdeMacBook-Pro:testcontract xj$ cleos get table testcontract testcontract students
{
  "rows": [{
      "id": 0,
      "studentName": "wangwu",
      "studentGender": "male",
      "studentAge": 11,
      "studentHeight": 120
    }
  ],
  "more": false
}

4.修改
xjdeMacBook-Pro:testcontract xj$ cleos push action testcontract update '["testcontract",0,"wangwu","male",12,123]' -p eosio@active
executed transaction: b895a437c9c205d769cdb3746b861b5164591f4cec70bfb047d5e0472e21a18b  128 bytes  1198 us
#  testcontract <= testcontract::update         {"s":"testcontract","id":0,"studentName":"wangwu","studentGender":"male","studentAge":12,"studentHei...
warning: transaction executed locally, but may not be confirmed by the network yet         ]
xjdeMacBook-Pro:testcontract xj$ cleos get table testcontract testcontract students
{
  "rows": [{
      "id": 0,
      "studentName": "wangwu",
      "studentGender": "male",
      "studentAge": 12,
      "studentHeight": 123
    }
  ],
  "more": false
}

5.删除
xjdeMacBook-Pro:testcontract xj$ cleos push action testcontract del '["testcontract",0]' -p eosio@active
executed transaction: f885c9e315a2d610fbeeefc887884c1e9b99ed21c1782bc1034eb67c6e3fda96  112 bytes  1172 us
#  testcontract <= testcontract::del            {"s":"testcontract","id":0}
warning: transaction executed locally, but may not be confirmed by the network yet         ]
xjdeMacBook-Pro:testcontract xj$ cleos get table testcontract testcontract students
{
  "rows": [],
  "more": false
}