开源数据访问组件DAC

不好意思，借首页作个广告，给大家介绍个开源的数据访问组件Data Access Component，项目网站:http://dac.codeplex.com .

项目描述:

数据访问组件，提供了一组类库和一个代码生成工具，使.net项目中数据访问更简化.

功能:

• 多种数据库支持.
• 提供DataSet, DataTable 和数据实体查询.
• 执行SQL脚本及存储过程.
• 条件表达式.
• 常用SQL方法, 如MAX, MIN等可能被应用在查询中.
• 数据实体代码及XML文件生成.

使用:

基本功能:

1. 使用 "EntitiesGenerator" 生成工具生成实体项目。
  参见 blog： How to use the "Enties Generator" tool to create an entities project.

2. 添加一个文件名为"connection.config"的数据库连接配置文件，到应用程序的运行目录，文件格式及内容如下：

<?xml version="1.0" encoding="utf-8" ?>
<connections>
  <connection databaseType="SQL">Data Source=.\SQLEXPRESS;AttachDbFilename="|DataDirectory|Database1.mdf";
  Integrated Security=True;User Instance=True</connection>
</connections>

3. 假定我们有个实体类，名叫 "Issue", 可以使用以下代码将它插入数据库

	RaisingStudio.Data.Providers.DataContext dc = new RaisingStudio.Data.Providers.DataContext();
	dc.Insert<Issue>(issue);

4. 更新实体.

	dc.Update<Issue>(issue);

5. 删除实体, 可以通过给定实体或实体的主键值进行。

	dc.Delete<Issue>(issue);

或

	dc.Delete<Issue>(issueID);

6. 查询实体, 通过三个不同的方法，可以分别获得 IEnumerable<T>, IList<T> or DataTable 作为返回结果。

	IEnumerable<Issue> query = dc.Query<Issue>();
	foreach(Issue issue in query)
	{
	}

	IList<Issue> issueList = dc.QueryForList<Issue>();

在查询中，还可以使用“条件表达式”.

	DataTable dataTable = dc.QueryForDataTable<Issue>(Issue._.IssueID > 1);

7. 可以通过GetData()方法，查询单个实体，使用包含主键值的实体，主键值或条件表达式作为参数。

	Issue issue = new Issue();
	issue.IssueID = 2;
	issue = dc.GetData<Issue>(issue);

	Issue issue = dc.GetData<Issue>(2);

	Issue issue = dc.GetData<Issue>(Issue._.IssueID == 2);

8. 更新DataTable.

	int result = dc.UpdateDataTable<Issue>(dataTable);

高级特性:

1. 常用SQL方法, 包括 GetCount, GetMin, GetMax, GetSum and GetAvg.

int result = dc.GetCount<Issue>();
object minValue = dc.GetMin<Issue>(Issue._.Progress);
decimal maxValue = Convert.ToDecimal(dc.GetMax<Issue>(Issue._.Progress,
              Issue._.Title == "test title"));

2. Save 和 Exists.

int result = dc.Save<Issue>(issue);
bool saved = dc.Exists<Issue>(issue);
bool ex = dc.Exists<Issue>(Issue._.Title == "test title");

3. 部分列.

Issue issue = dc.GetData<issue>(2, Issue._.Status);
issue.Status = IssueStatus.Fixed;
int result  = dc.Update<Issue>(issue, Issue._.Status);

4. 批量操作.

int result = dc.Delete<issue>(Issue._.Status == IssueStatus.Fixed);
result  = dc.Update<Issue>(issue, Issue._.Status == IssueStatus.Fixed, Issue._.Status);

5. 排序, 使用 "OrderBy" 方法或  ^ 和  ^ ! 运算符应用在查询中，可以对查询进行排序.

IEnumerable<Issue> query = dc.Query<Issue>(Issue.All.OrderBy(Issue._.IssueID));
query = dc.Query<Issue>(Issue._.Status == IssueStatus.Fixed ^ Issue._.IssueID);

6. 分页.

 IList<Issue> issueList = dc.QueryForList<Issue>(Issue.All, 0, 100);

7. 事务.

try
{
    this.dc.BeginTransaction();
    try
    {
        int result = this.dc.Insert<Issue>(issue);              
        this.dc.CommitTransaction();
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.WriteLine(ex);
        this.dc.RollbackTransaction();
        throw;
    }
}
catch (Exception ex)
{
    System.Diagnostics.Debug.WriteLine(ex);
    throw;
}

8. 多主键.

MutipleKeysTable mt = dc.GetData<MutipleKeysTable>(new object[] { key1, key2 }, 
             MutipleKeysTable.Except(MutipleKeysTable._.Value2));

9. 使用 common command 查询.

CommonCommand cmd = new CommonCommand();
cmd.CommandText = string.Format("SELECT [IssueID], [{0}] FROM .[Issue] WHERE [{0}] = @p1", Issue._.Title);
cmd.Parameters.Add("@p1", "test title");
Issue issue = dc.GetData<Issue>(cmd);

10. 执行 common command, 支持 ExecuteForDataTable, ExecuteForList, ExecuteQuery, ExecuteReader, ExecuteScalar 和 ExecuteNoQuery 等方法.

RaisingStudio.Data.CommonCommand cmd = new CommonCommand(
              string.Format("UPDATE .[{0}] SET [{1}] = [{1}] + 1 WHERE [{2}] = @p1",
              Issue._, Issue._.Progress, Issue._.IssueID));
cmd.AddParameter("@p1", System.Data.DbType.Int32, maxID);
int result = this.dc.ExecuteNoQuery<Issue>(cmd);

11. SQL 脚本日志.

DataContext dc = new DataContext();
dc.Log = System.Console.Out;

12. 多种数据库 providers, 添加如下的 xml 项到 "providers.config" 配置文件中, 就可以在 "connections.config" 中使用.

    <provider 
    name="MYSQL" 
    description="MySQL, MySQL provider " 
    enabled="false" 
    assemblyName="MySql.Data, Version=5.2.5.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" 
   connectionClass="MySql.Data.MySqlClient.MySqlConnection" 
    commandClass="MySql.Data.MySqlClient.MySqlCommand" 
    parameterClass="MySql.Data.MySqlClient.MySqlParameter" 
    parameterDbTypeClass="MySql.Data.MySqlClient.MySqlDbType" 
    parameterDbTypeProperty="MySqlDbType" 
    dataAdapterClass="MySql.Data.MySqlClient.MySqlDataAdapter" 
    commandBuilderClass="MySql.Data.MySqlClient.MySqlCommandBuilder" 
    usePositionalParameters="false" 
    useParameterPrefixInSql="true" 
    useParameterPrefixInParameter="true" 
    parameterPrefix="?"
    allowMARS="false"    
  />

13. 自定义数据类型“转换器”,  以下就是一个 "TypeConverter" 示例代码，及如何配置到 "converters.config" 配置文件中.

public class PointConverter : IDbTypeConverter
{
	#region IDbTypeConvertermember
	public object ConvertFromDbType(object value)
	{
		string s = value as string;
		if (!string.IsNullOrEmpty(s))
		{
			string[] sa = s.Split(',');
			if ((sa != null) && (sa.Length == 3))
			{
				int x = int.Parse(sa[0]);
				int y = int.Parse(sa[1]);
				int z = int.Parse(sa[2]);
				return new Point(x, y, z);
			}
		}
		return null;
	}
	public object ConvertToDbType(object value)
	{
		if (value is Point)
		{
			Point point = (Point)value;
			return point.ToString();
		}
		return null;
	}
	#endregion
}

    <converter type="RaisingStudio.Data.Entities.Point, 
RaisingStudio.Data.Entities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" 
dbType="string" 
converterType="RaisingStudio.Data.Entities.PointConverter, 
RaisingStudio.Data.Entities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null">
</converter>

14. “实体定义”配置, "*.definition.xml" 文件可以作为资源文件嵌入到程序集在，也可以留在文件系统上，"EntitiesGenerator" 实体生成工具生在项目是采用的嵌入资源的方式， 如果要使用文件的方式，则需要配置一个名叫"definitions.config"的配置文件，样式如下：

<?xml version="1.0" encoding="utf-8"?>
<definitionsConfig xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <aliases>
    <alias name="UTIssue" type="UnitTest.UTIssue, UnitTest, Version=1.0.0.0, 
             Culture=neutral, PublicKeyToken=null" />
  </aliases>
  <definitions>
    <definition name="UTIssue" resource="definitions/Issue.definition.xml" />
    <definition name="UTSystemUser" resource="definitions/SystemUser.definition.xml" />
  </definitions>  
</definitionsConfig>

15. Common command 管理器. 把 SQL脚本配置在 "commands.config" 中后，可以用如下代码读取使用。

<?xml version="1.0" encoding="utf-8" ?>
<commands parameterPrefix=":">
  <command name="select">SELECT * FROM DAC_ISSUE</command>
  <command name="select2">
    <![CDATA[
    SELECT * FROM DAC_USER
    ]]>
  </command>
  <command name="select3" commandType="StoredProcedure">SELECT_DAC_ISSUE</command>
  <command name="select4">
    <![CDATA[
    SELECT * FROM DAC_ISSUE DI
    WHERE DI.ISSUE_ID = :ISSUE_ID
    ]]>
  </command>
</commands>

CommonCommand cmd = CommandManager.Instance.GetCommand("select");
System.Data.DataTable dt = this.dc.ExecuteForDataTable(cmd);