EOSIO Developer Portal 解説　データの永続化とインラインアクション 第1回

はじめに

EOSにおけるデータの扱い

EOSの手数料とストレージ

EOSIO Database

サンプルコントラクトによる実装

$ cd CONTRACTS_DIR
$ mkdir addressbook
$ cd addressbook
$ touch addressbook.cpp

#include 

using namespace eosio;

class [[eosio::contract]] addressbook : public eosio::contract {
  public:
       
  private: 
  
};

private:
  struct [[eosio::table]] person {
    name key;
    std::string first_name;
    std::string last_name;
    std::string street;
    std::string city;
    std::string state;
    uint64_t primary_key() const { return key.value; }
  };

typedef eosio::multi_index<"people"_n, person> address_index;

public:
  using contract::contract;
  
  addressbook(name receiver, name code,  datastream ds): contract(receiver, code, ds) {}

 [[eosio::action]]
  void upsert(name user, std::string first_name, std::string last_name, std::string street, std::string city, std::string state) {
    require_auth( user );
    address_index addresses(_code, _code.value);
    auto iterator = addresses.find(user.value);
    if( iterator == addresses.end() )
    {
      addresses.emplace(user, [&]( auto& row ) {
       row.key = user;
       row.first_name = first_name;
       row.last_name = last_name;
       row.street = street;
       row.city = city;
       row.state = state;
      });
    }
    else {
      std::string changes;
      addresses.modify(iterator, user, [&]( auto& row ) {
        row.key = user;
        row.first_name = first_name;
        row.last_name = last_name;
        row.street = street;
        row.city = city;
        row.state = state;
      });
    }
  }

  [[eosio::action]]
  void erase(name user) {
    require_auth(user);

    address_index addresses(_self, _code.value);

    auto iterator = addresses.find(user.value);
    eosio_assert(iterator != addresses.end(), "Record does not exist");
    addresses.erase(iterator);
  }

EOSIO_DISPATCH( addressbook, (upsert)(erase) )

サンプルコントラクトによる動作確認

$ eosio-cpp -o addressbook.wasm addressbook.cpp --abigen

$ cleos create account eosio addressbook YOUR_PUBLIC_KEY YOUR_PUBLIC_KEY -p eosio@active

$ cleos set contract addressbook CONTRACTS_DIR/addressbook -p addressbook@active

5f78f9aea400783342b41a989b1b4821ffca006cd76ead38ebdf97428559daa0  5152 bytes  727 us
#         eosio <= eosio::setcode               {"account":"addressbook","vmtype":0,"vmversion":0,"code":"0061736d010000000191011760077f7e7f7f7f7f7f...
#         eosio <= eosio::setabi                {"account":"addressbook","abi":"0e656f73696f3a3a6162692f312e30010c6163636f756e745f6e616d65046e616d65...
warning: transaction executed locally, but may not be confirmed by the network yet    ]

$ cleos push action addressbook upsert '["alice", "alice", "liddell", "123 drink me way", "wonderland", "amsterdam"]' -p alice@active

executed transaction: 003f787824c7823b2cc8210f34daed592c2cfa66cbbfd4b904308b0dfeb0c811  152 bytes  692 us
#   addressbook <= addressbook::upsert          {"user":"alice","first_name":"alice","last_name":"liddell","street":"123 drink me way","city":"wonde..

$ cleos get table addressbook addressbook people --lower alice --limit 1

{
  "rows": [{
      "key": "3773036822876127232",
      "first_name": "alice",
      "last_name": "liddell",
      "street": "123 drink me way",
      "city": "wonderland",
      "state": "amsterdam"
    }
  ],
  "more": false
}

$ cleos push action addressbook upsert '["bob", "bob", "is a loser", "doesnt exist", "somewhere", "someplace"]' -p alice@active

Error 3090004: Missing required authority
Ensure that you have the related authority inside your transaction!;
If you are currently using 'cleos push action' command, try to add the relevant authority using -p option.

$ cleos push action addressbook erase '["alice"]' -p alice@active

executed transaction: 0a690e21f259bb4e37242cdb57d768a49a95e39a83749a02bced652ac4b3f4ed  104 bytes  1623 us
#   addressbook <= addressbook::erase           {"user":"alice"}
warning: transaction executed locally, but may not be confirmed by the network yet    ]

$ cleos get table addressbook addressbook people --lower alice --limit 1

{
  "rows": [],
  "more": false
}

参考文献：

• EOSIO Developer Portal – 2.4 Data Persistence

• EOSIO Developer Portal – Multi-Index DB API