EOS 智能合约中数据表的操作方法

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netkiller old

发布于 2018-07-19 09:37:22

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发布于 2018-07-19 09:37:22

文章被收录于专栏：Netkiller

本文节选自电子书《Netkiller Blockchain 手札》

Netkiller Blockchain 手札

Mr. Neo Chan, 陈景峯(BG7NYT)

中国广东省深圳市龙华新区民治街道溪山美地 518131 +86 13113668890 <netkiller@msn.com>

文档始创于2018-02-10

转载请与作者联系，转载时请务必标明文章原始出处和作者信息及本声明。

网站：http://www.netkiller.cn
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QQ群：128659835 请注明“读者”

内容摘要

这一部关于区块链开发及运维的电子书。

为什么会写区块链电子书？因为2018年是区块链年，区块链是一个风口，前几个风口我都错过了。例如web2.0, 云，大数据等等，都从身旁擦肩而过。所以我要抓住这次。

这本电子书是否会出版（纸质图书）？不会，因为互联网技术更迭太快，纸质书籍的内容无法实时更新，一本书动辄百元，很快就成为垃圾，你会发现目前市面的上区块链书籍至少是一年前写的，内容已经过时，很多例子无法正确运行。所以我不会出版，电子书的内容会追逐技术发展，及时跟进软件版本的升级，做到内容最新，至少是主流。

这本电子书与其他区块链书籍有什么不同？市面上大部分区块链书籍都是用2/3去讲区块链原理，只要不到 1/3 的干货，干货不够理论来凑，通篇将理论或是大谈特谈区块链行业，这些内容更多是头脑风暴，展望区块链，均无法落地实施。本书与那些书籍完全不同，不讲理论和原理，面向应用落地，注重例子，均是干货。

写作原则，无法落地的项目作者绝对不会写。凡是写入电子的内容均具备可操作，可落地。

电子书更新频率？每天都会有新内容加入，更新频率最迟不会超过一周，更新内容请关注 https://github.com/netkiller/netkiller.github.io/commits/master

本文采用碎片化写作，原文会不定期更新，请尽量阅读原文 http://www.netkiller.cn/blockchain/index.html

您的打赏是我的写作动力：http://www.netkiller.cn/blockchain/donations.html

接受 ETH 打赏：0x3e827461Cc53ed7c75A29187CfF39629FCAE3661

6.7. 智能合约数据库操作 CURD

为了方便调试合约

找到config.ini中的配置项contracts-console = false 改为 true

[root@netkiller ~]# vim ~/.local/share/eosio/nodeos/config/config.ini

# print contract's output to console (eosio::chain_plugin)
contracts-console = true

这样 eosio::print() 输出的内容才会显示在控制台上。

6.7.1. 创建一个新项目

eosiocpp -n project

6.7.2. 创建结构体

例如我们需要这样一个数据结构

{
	id,
	description,
	completed
}

结构体定义如下

struct todo {
	uint64_t id;
	std::string description;
	uint64_t completed;

	uint64_t primary_key() const { return id; }
	EOSLIB_SERIALIZE(todo, (id)(description)(completed))
};

primary_key() 相当与数据中的主键。

定义一个表

typedef eosio::multi_index<N(todos), todo> todo_table;
todo_table todos;

6.7.3. 插入数据操作

void create(account_name author, const uint32_t id, const std::string& description) {
	todos.emplace(author, [&](auto& new_todo) {
		new_todo.id  = id;
		new_todo.description = description;
		new_todo.completed = 0;
	});

6.7.4. 修改数据操作

void complete(account_name author, const uint32_t id) {
      auto todo_lookup = todos.find(id);
      eosio_assert(todo_lookup != todos.end(), "Todo does not exist");

      todos.modify(todo_lookup, author, [&](auto& modifiable_todo) {
        modifiable_todo.completed = 1;
      });

      eosio::print("todo#", id, " marked as complete");
    }

6.7.5. 删除数据操作

void destroy(account_name author, const uint32_t id) {
	auto todo_lookup = todos.find(id);
	todos.erase(todo_lookup);

	eosio::print("todo#", id, " destroyed");
}

6.7.6. 完整的合约例子

#include <eosiolib/eosio.hpp>
#include <string>

namespace eosio {
using std::string;
  class netkiller : public contract {
     public:
           netkiller( account_name self ):contract(self){}

           void create(account_name author, string title, string content);
           void change(account_name author, uint64_t post_id, string title, string content);
           void remove(account_name author, uint64_t post_id);
           void find(uint64_t post_id, account_name author);

     private:

           struct da {
                 uint64_t     post_id;
                 account_name poster;
                 string       title;
                 string       content;

                 uint64_t primary_key()const { return post_id; }
                 account_name get_poster() const { return poster; }

                 EOSLIB_SERIALIZE(da, (post_id)(poster)(title)(content))
           };
           typedef eosio::multi_index<N(data), da, indexed_by<N(byposter), const_mem_fun<da, account_name, &da::get_poster>> > article;
  };
}

#include "netkiller.hpp"

namespace eosio {

    void netkiller::create(account_name author, string title, string content)
    {
        require_auth( author );
        article datable( _self, _self);
        datable.emplace(author, [&]( da & d){
            d.title = title;
            d.content = content;
            d.post_id = datable.available_primary_key();
            d.poster = author;
        });
    }

    void netkiller::change(account_name author, uint64_t post_id, string title, string content)
    {
        require_auth(author);
        article datable( _self, author);
        auto post = datable.find(post_id);
        eosio_assert(post->poster == author, "netkiller");
        datable.modify(post, author, [&](auto& p){
            if (title != "")
                p.title = title;
            if (content != "")
                p.content = content;
        });
    }

    void netkiller::remove(account_name author, uint64_t post_id)
    {
        require_auth(author);
        article datable( _self, author);
        auto post = datable.find(post_id);
        eosio::print(post->title.c_str());

        eosio_assert(post->poster == author, "The author is invlide");
        datable.erase(post);
    }

    void netkiller::find(uint64_t post_id, account_name author){
        article datable(_self, _self);
        auto post_da = datable.find( post_id);
        eosio::print("Post_id: ", post_da->post_id, "  Post_Tile: ", post_da->title.c_str(), " Content: ", post_da->content.c_str());

        auto poster_index = datable.template get_index<N(byposter)>();
        auto pos = poster_index.find( author );

        for (; pos != poster_index.end(); pos++)
        {
            eosio::print("content:", pos->content.c_str(), " post_id:", pos->post_id, " title:", pos->title.c_str());
        }
    }

}
EOSIO_ABI(eosio::netkiller, (create)(change)(remove)(find))

6.7.6.1. 编译

eosiocpp -o cms.wast cms.cpp	
eosiocpp -g cms.abi cms.cpp

6.7.6.2. 启动EOS私链开发环境

nodeos -e -p eosio --plugin eosio::chain_api_plugin --plugin eosio::history_api_plugin --plugin eosio::wallet_api_plugin

6.7.6.3. 创建合约账号

这里我们创建一个账号，用这个账号部署合约，该账号是合约所有者。

创建秘钥对

[root@netkiller ~]# cleos wallet unlock		
				
[root@netkiller ~]# cleos create key
Private key: 5HxCWNbTEADKbvdRBgeENXhxReHMQbVuPL5mumDqGCzmkPo5yy3
Public key: EOS7WEcxxHcmM7w7DHB56N6qQ2toMrdudYjeDTZb6LtL9g77MXzR4

导入私钥

[root@netkiller ~]# cleos wallet import 5HxCWNbTEADKbvdRBgeENXhxReHMQbVuPL5mumDqGCzmkPo5yy3
imported private key for: EOS7WEcxxHcmM7w7DHB56N6qQ2toMrdudYjeDTZb6LtL9g77MXzR4		
	
[root@netkiller ~]# cleos wallet keys | grep EOS7WEcxxHcmM7w7DHB56N6qQ2toMrdudYjeDTZb6LtL9g77MXzR4
  "EOS7WEcxxHcmM7w7DHB56N6qQ2toMrdudYjeDTZb6LtL9g77MXzR4",

创建账号 neo

[root@netkiller ~]# cleos create account eosio contract.cms EOS7WEcxxHcmM7w7DHB56N6qQ2toMrdudYjeDTZb6LtL9g77MXzR4 EOS7WEcxxHcmM7w7DHB56N6qQ2toMrdudYjeDTZb6LtL9g77MXzR4
executed transaction: f04ba09f633dffbf97321c6d2e021192082383908fa690dc40032cd98a1bfd89  200 bytes  390 us
#         eosio <= eosio::newaccount            "0000000000ea305590af0119999b274501000000010003588ecdc868696f500c7782dbf0da3b298830e67ea9b810469819d...
warning: transaction executed locally, but may not be confirmed by the network yet

contract.art 就是我们合约账号，我们使用 contract 前缀来区分他是合约账号。

6.7.6.4. 部署合约

[root@netkiller eos]# cleos wallet unlock
password: Unlocked: default

[root@netkiller eos]# cleos set contract contract.cms cms
Reading WAST/WASM from cms/cms.wasm...
Using already assembled WASM...
Publishing contract...
executed transaction: 8a72e29389e170807daaf41e9c9e70ac4eff2f2f129ca22ef55ca9443768dedf  7176 bytes  1311 us
#         eosio <= eosio::setcode               "80250219999b27450000c3770061736d0100000001b2011b60037f7e7e0060027f7e0060057f7e7e7f7f0060047f7e7f7f0...
#         eosio <= eosio::setabi                "80250219999b27459d020e656f73696f3a3a6162692f312e30000506637265617465000306617574686f72046e616d65057...
warning: transaction executed locally, but may not be confirmed by the network yet

6.7.6.5. 创建

cleos push action contract.cms create '{"author":"contract.cms","title":"hello","content":"helloworld!!!"}' -p contract.cms

[root@netkiller eos]# cleos push action contract.art create '{"author":"contract.art","title":"hello","content":"helloworld!!!"}' -p contract.art
executed transaction: b6cab608fb4e7fa17a7f893848f3516e1bfd231769ad7d7226b0a099f309a771  120 bytes  899 us
#  contract.art <= contract.art::create         {"author":"contract.cms","title":"hello","content":"helloworld!!!"}
warning: transaction executed locally, but may not be confirmed by the network yet

[root@netkiller eos]# cleos push action contract.cms create '{"author":"neo","title":"hello","content":"helloworld!!!"}' -p neo
executed transaction: 90cb81b11386514b450e1a609f0e1e2633f6a4e40d453c127811e5cd33b46a5a  120 bytes  755 us
#  contract.art <= contract.art::create         {"author":"neo","title":"hello","content":"helloworld!!!"}
warning: transaction executed locally, but may not be confirmed by the network yet

下面我们来查询一下刚刚插入的数据：

6.7.6.6. 查找

find

[root@netkiller eos]# cleos push action contract.cms find '{"id":0}' -p contract.cms
executed transaction: b3cba4d001fcb49a88926be208fa7bee59d557b0ed8a2bd12e65bdd3ff69c61e  104 bytes  486 us
#  contract.cms <= contract.cms::find           {"id":0}
>> id: 0 Tile: hello Content: helloworld!!!

query

[root@netkiller eos]# cleos push action contract.cms query '{"author":"contract.cms", "id":0}' -p contract.cms 
executed transaction: c81a0d21634f4942f7d65dd49efcf5cf7cd739a049968b5f9b0eaad7de4c688c  112 bytes  583 us
#  contract.cms <= contract.cms::query          {"author":"contract.cms","id":0}
>> Post_id: 0  Post_Tile: hello Content: helloworld!!!content:helloworld!!! id:0 title:hello

6.7.6.7. 修改

修改表中的数据

[root@netkiller eos]# cleos push action contract.cms change '{"author":"contract.cms","id":0,"title":"word","content":"china"}' -p contract.cms
executed transaction: 073205e4e3e30699a81394ee622aa84d568958919801b364d809ff34f4ca8412  120 bytes  553 us
#  contract.cms <= contract.cms::change         {"author":"contract.cms","id":0,"title":"word","content":"china"}

检查数据修改情况

[root@netkiller eos]# cleos push action contract.cms find '{"id":0}' -p contract.cms
executed transaction: 300fe2c93cf2cfebcdd0524e0629a96b3011b0592be2119d001f38807c1c378b  104 bytes  498 us
#  contract.cms <= contract.cms::find           {"id":0}
>> id: 0 Tile: word Content: china

6.7.6.8. 删除

[root@netkiller eos]# cleos push action contract.cms remove '{"author":"contract.cms","id":0}' -p contract.cms
executed transaction: eeee8ff799c58d5e3a246ccec8d80c47599ad947d4581611d9a668abee53c0b5  112 bytes  770 us
#  contract.cms <= contract.cms::remove         {"author":"contract.cms","id":0}
>> word

检查被删除的数据，提示 Error 3070002: Runtime Error Processing WASM 表示找不到该记录。

[root@netkiller eos]# cleos push action contract.cms find '{"id":0}' -p contract.cms
Error 3070002: Runtime Error Processing WASM

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

其他

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

其他

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