一直以來，筆者都在不停尋找一種更人性化的數據庫訪問方式（並不是說默認的方式不好，而是有時候的確在模塊化設計中不太方便）。
後來有幸在php中找到codeigniter的ActiveReord，詳細參考這篇文章: 抽離CodeIgniter的數據庫訪問類！
然而c++卻始終用著最原始的方式，昨天趁著項目要用的機會，在網上搜索了好久，總算讓我找到兩套c++的數據庫訪問框架:
soci
litesql
兩套代碼我都拿下來看了一下，litesql實現了一套完整的代碼自動生成，功能強大，但是也很重；soci相對要輕量，但是同樣也實現了數據結構到數據庫表的映射。本人還是比較喜歡輕量的東西，所以最終選擇了soci。經過這兩天的試用，感覺非常不錯。
官方的文檔也很詳細，所以這裡就用我寫的單元測試代碼來做一下簡單的講解:
首先創建庫表:
create database soci; CREATE TABLE `tb_test` ( `id` int(11) NOT NULL auto_increment, `name` varchar(32) default "", `sex` int(11) default 0, PRIMARY KEY (`id`), UNIQUE KEY `name` (`name`) ); create database soci; CREATE TABLE `tb_test` ( `id` int(11) NOT NULL auto_increment, `name` varchar(32) default "", `sex` int(11) default 0, PRIMARY KEY (`id`), UNIQUE KEY `name` (`name`) );
1.簡單的select單條記錄
TEST(soci,select_one)
{
try
{
session sql(mysql, "host=localhost db=soci user=dantezhu");
indicator ind;
string name = "dandan";
int sex;
sql << "select sex from tb_test where name = :name",
into(sex, ind), use(name);
ASSERT_EQ(ind, i_ok) << name;
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
TEST(soci,select_one)
{
try
{
session sql(mysql, "host=localhost db=soci user=dantezhu");
indicator ind;
string name = "dandan";
int sex;
sql << "select sex from tb_test where name = :name",
into(sex, ind), use(name);
ASSERT_EQ(ind, i_ok) << name;
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
select的結果，如果成功則ind會為i_ok，同值sex被賦值；如果失敗則反之
2.簡單的select多條記錄
TEST(soci,select_multi2)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
indicator ind;
int count;
sql << "select count(*) from tb_test", into(count, ind);
ASSERT_EQ(ind, i_ok) << count;
if (count == 0)
{
SUCCEED();
return;
}
int sex = 1;
vector<string> vec_name(count);
vector<int> vec_sex(count);
sql << "select name,sex from tb_test where sex = :sex",
into(vec_name), into(vec_sex), use(sex);
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
TEST(soci,select_multi2)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
indicator ind;
int count;
sql << "select count(*) from tb_test", into(count, ind);
ASSERT_EQ(ind, i_ok) << count;
if (count == 0)
{
SUCCEED();
return;
}
int sex = 1;
vector<string> vec_name(count);
vector<int> vec_sex(count);
sql << "select name,sex from tb_test where sex = :sex",
into(vec_name), into(vec_sex), use(sex);
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
與select單條記錄唯一的區別即，into()的參數是一個vector。其實用多個vector這種方式並不是一個很好的選擇，後面會介紹基於數據結構的方式。
3.簡單的insert
TEST(soci,insert_exist)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
string name = "dandan";
int sex = 1;
sql << "insert into tb_test(name, sex) values(:name, :sex)",
use(name), use(sex);
}
catch (exception const &e)
{
SUCCEED()<<e.what();
}
}
TEST(soci,insert_exist)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
string name = "dandan";
int sex = 1;
sql << "insert into tb_test(name, sex) values(:name, :sex)",
use(name), use(sex);
}
catch (exception const &e)
{
SUCCEED()<<e.what();
}
}
insert，update，delete都有兩個同樣的問題:
a)affect_rows(操作的行數)沒有辦法返回
b)操作的id無法知道，尤其對於insert的主鍵是自增的情況下，無法知道插入的主鍵的值是多少。
update和delete都與insert相似，這裡就不再多說。
接下來是這個框架的很重要的一個特性，即數據庫表與數據結構綁定：
首先我們需要定義一個結構體，並告知soci怎麼讓列名和數據結構的字段對應起來:
struct Person
{
int id;
std::string name;
int sex;
};
namespace soci
{
template<> struct type_conversion<Person>
{
typedef values base_type;
static void from_base(values const & v, indicator /* ind */, Person & p)
{
p.id = v.get<int>("id");
p.name = v.get<std::string>("name");
p.sex = v.get<int>("sex");
}
static void to_base(const Person & p, values & v, indicator & ind)
{
v.set("id", p.id);
v.set("name", p.name);
v.set("sex", p.sex);
ind = i_ok;
}
};
}
struct Person
{
int id;
std::string name;
int sex;
};
namespace soci
{
template<> struct type_conversion<Person>
{
typedef values base_type;
static void from_base(values const & v, indicator /* ind */, Person & p)
{
p.id = v.get<int>("id");
p.name = v.get<std::string>("name");
p.sex = v.get<int>("sex");
}
static void to_base(const Person & p, values & v, indicator & ind)
{
v.set("id", p.id);
v.set("name", p.name);
v.set("sex", p.sex);
ind = i_ok;
}
};
}
關於
template<> struct type_conversion<Person> template<> struct type_conversion<Person>
這裡，官方的文檔是是有誤的，我查了好長時間，按照上面的寫法來寫即可。
1.用數據結構來select
TEST(soci,select_obj_one)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
indicator ind;
int count;
sql << "select count(*) from tb_test", into(count, ind);
ASSERT_EQ(ind, i_ok) << count;
string name = "dandan";
Person p;
sql << "select id,name,sex from tb_test where name = :name",
into(p, ind), use(name);
ASSERT_EQ(ind, i_ok) << name;
if (sql.got_data())
{
cout<< p.id
<< ","
<< p.name
<< ","
<< p.sex
<< endl;
}
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
TEST(soci,select_obj_one)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
indicator ind;
int count;
sql << "select count(*) from tb_test", into(count, ind);
ASSERT_EQ(ind, i_ok) << count;
string name = "dandan";
Person p;
sql << "select id,name,sex from tb_test where name = :name",
into(p, ind), use(name);
ASSERT_EQ(ind, i_ok) << name;
if (sql.got_data())
{
cout<< p.id
<< ","
<< p.name
<< ","
<< p.sex
<< endl;
}
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
2.用數據結構來進行insert
TEST(soci,insert_obj_noexist)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
Person p = {
0,
"niuniu",
2
};
sql << "insert into tb_test(name, sex) values(:name, :sex)",
use(p);
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
TEST(soci,insert_obj_noexist)
{
try
{
session sql(mysql, "db=soci user=dantezhu");
Person p = {
0,
"niuniu",
2
};
sql << "insert into tb_test(name, sex) values(:name, :sex)",
use(p);
}
catch (exception const &e)
{
FAIL()<<e.what();
}
}
整個就是這樣~~下面是文中代碼文件的下載路徑：
http://code.google.com/p/vimercode/source/browse/#svn%2Ftrunk%2Fsoci_test
另外，雖然python下的mysql訪問也算比較簡單，但還是想知道是否有更Pythonic的庫或接口，如果有朋友知道，歡迎不吝告知。
