T4模版引擎之生成数据库实体类-mysql教程-PHP中文网

在通过T4模版引擎之基础入门对T4有了初步印象后，我们开始实战篇。T4模板引擎可以当做一个代码生成器，代码生成器的职责当然是用来生成代码(这不是废话吗)。而这其中我们使用的最普遍的是根据数据库生成实体类。工欲善其事必先利其器，在这之前先来介绍一

　　在通过t4模版引擎之基础入门对t4有了初步印象后，我们开始实战篇。t4模板引擎可以当做一个代码生成器，代码生成器的职责当然是用来生成代码(这不是废话吗)。而这其中我们使用的最普遍的是根据数据库生成实体类。

　　工欲善其事必先利其器，在这之前先来介绍一款T4编辑器T4 Editor，我们可以点击链接去下载然后安装，不过还是推荐大家直接在VS扩展管理器里直接安装来的方便工具->扩展管理器->联机库搜索 "T4 Editor"，选择第一项 "tangible T4 Editor 2.0 plus modeling tools for VS2010" 进行安装即可，如下图所示:

T4模版引擎之生成数据库实体类

安装上T4 Editor后，编辑T4模板是就有代码着色和智能提示了，下图为安装T4 Editor后的代码着色效果，怎么样是不是耳目一新，呵呵

T4模版引擎之生成数据库实体类

接下来开始正式进入我们的主题，从数据库自动生成实体类

新建一个控制台项目，然后添加T4模板，这里我们起名字为Customers.tt

修改输出文件扩展名为.cs

<span><</span><span>#@ output </span><span>extension</span><span>=".cs"</span><span> #</span><span>></span>

登录后复制

添加常用的程序集和命名空间引用

<span><</span><span>#@ assembly </span><span>name</span><span>="System.Core.dll"</span><span> #</span><span>></span>
<span><</span><span>#@ assembly </span><span>name</span><span>="System.Data.dll"</span><span> #</span><span>></span>
<span><</span><span>#@ assembly </span><span>name</span><span>="System.Data.DataSetExtensions.dll"</span><span> #</span><span>></span>
<span><</span><span>#@ assembly </span><span>name</span><span>="System.Xml.dll"</span><span> #</span><span>></span>
<span><</span><span>#@ import </span><span>namespace</span><span>="System"</span><span> #</span><span>></span>
<span><</span><span>#@ import </span><span>namespace</span><span>="System.Xml"</span><span> #</span><span>></span>
<span><</span><span>#@ import </span><span>namespace</span><span>="System.Linq"</span><span> #</span><span>></span>
<span><</span><span>#@ import </span><span>namespace</span><span>="System.Data"</span><span> #</span><span>></span>
<span><</span><span>#@ import </span><span>namespace</span><span>="System.Data.SqlClient"</span><span> #</span><span>></span>
<span><</span><span>#@ import </span><span>namespace</span><span>="System.Collections.Generic"</span><span> #</span><span>></span>
<span><</span><span>#@ import </span><span>namespace</span><span>="System.IO"</span><span> #</span><span>></span>

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添加数据库操作DbHelper引用

T4模版引擎之生成数据库实体类 DbHelper.ttinclude

<#+
    <span>public</span> <span>class</span><span> DbHelper
    {
        </span><span>#region</span> GetDbTables
        
        <span>public</span> <span>static</span> List<DbTable> GetDbTables(<span>string</span> connectionString, <span>string</span> database, <span>string</span> tables = <span>null</span><span>)
        {
            
            </span><span>if</span> (!<span>string</span><span>.IsNullOrEmpty(tables))
            {
                tables </span>= <span>string</span>.Format(<span>"</span><span> and obj.name in ('{0}')</span><span>"</span>, tables.Replace(<span>"</span><span>,</span><span>"</span>, <span>"</span><span>','</span><span>"</span><span>));
            }
            </span><span>#region</span> SQL
            <span>string</span> sql = <span>string</span>.Format(<span>@"</span><span>SELECT
                                    obj.name tablename,
                                    schem.name schemname,
                                    idx.rows,
                                    CAST
                                    (
                                        CASE 
                                            WHEN (SELECT COUNT(1) FROM sys.indexes WHERE object_id= obj.OBJECT_ID AND is_primary_key=1) >=1 THEN 1
                                            ELSE 0
                                        END 
                                    AS BIT) HasPrimaryKey                                         
                                    from {0}.sys.objects obj 
                                    inner join {0}.dbo.sysindexes idx on obj.object_id=idx.id and idx.indid<=1
                                    INNER JOIN {0}.sys.schemas schem ON obj.schema_id=schem.schema_id
                                    where type='U' {1}
                                    order by obj.name</span><span>"</span><span>, database, tables);
            </span><span>#endregion</span><span>
            DataTable dt </span>=<span> GetDataTable(connectionString, sql);
            </span><span>return</span> dt.Rows.Cast<DataRow>().Select(row => <span>new</span><span> DbTable
            {
                TableName </span>= row.Field<<span>string</span>>(<span>"</span><span>tablename</span><span>"</span><span>),
                SchemaName </span>= row.Field<<span>string</span>>(<span>"</span><span>schemname</span><span>"</span><span>),
                Rows </span>= row.Field<<span>int</span>>(<span>"</span><span>rows</span><span>"</span><span>),
                HasPrimaryKey </span>= row.Field<<span>bool</span>>(<span>"</span><span>HasPrimaryKey</span><span>"</span><span>)
            }).ToList();
        }
        </span><span>#endregion</span>

        <span>#region</span> GetDbColumns
        
        <span>public</span> <span>static</span> List<DbColumn> GetDbColumns(<span>string</span> connectionString, <span>string</span> database, <span>string</span> tableName, <span>string</span> schema = <span>"</span><span>dbo</span><span>"</span><span>)
        {
            </span><span>#region</span> SQL
            <span>string</span> sql = <span>string</span>.Format(<span>@"</span><span>
                                    WITH indexCTE AS
                                    (
                                        SELECT 
                                        ic.column_id,
                                        ic.index_column_id,
                                        ic.object_id    
                                        FROM {0}.sys.indexes idx
                                        INNER JOIN {0}.sys.index_columns ic ON idx.index_id = ic.index_id AND idx.object_id = ic.object_id
                                        WHERE  idx.object_id =OBJECT_ID(@tableName) AND idx.is_primary_key=1
                                    )
                                    select
                                    colm.column_id ColumnID,
                                    CAST(CASE WHEN indexCTE.column_id IS NULL THEN 0 ELSE 1 END AS BIT) IsPrimaryKey,
                                    colm.name ColumnName,
                                    systype.name ColumnType,
                                    colm.is_identity IsIdentity,
                                    colm.is_nullable IsNullable,
                                    cast(colm.max_length as int) ByteLength,
                                    (
                                        case 
                                            when systype.name='nvarchar' and colm.max_length>0 then colm.max_length/2 
                                            when systype.name='nchar' and colm.max_length>0 then colm.max_length/2
                                            when systype.name='ntext' and colm.max_length>0 then colm.max_length/2 
                                            else colm.max_length
                                        end
                                    ) CharLength,
                                    cast(colm.precision as int) Precision,
                                    cast(colm.scale as int) Scale,
                                    prop.value Remark
                                    from {0}.sys.columns colm
                                    inner join {0}.sys.types systype on colm.system_type_id=systype.system_type_id and colm.user_type_id=systype.user_type_id
                                    left join {0}.sys.extended_properties prop on colm.object_id=prop.major_id and colm.column_id=prop.minor_id
                                    LEFT JOIN indexCTE ON colm.column_id=indexCTE.column_id AND colm.object_id=indexCTE.object_id                                        
                                    where colm.object_id=OBJECT_ID(@tableName)
                                    order by colm.column_id</span><span>"</span><span>, database);
            </span><span>#endregion</span><span>
            SqlParameter param </span>= <span>new</span> SqlParameter(<span>"</span><span>@tableName</span><span>"</span>, SqlDbType.NVarChar, <span>100</span>) { Value = <span>string</span>.Format(<span>"</span><span>{0}.{1}.{2}</span><span>"</span><span>, database, schema, tableName) };
            DataTable dt </span>=<span> GetDataTable(connectionString, sql, param);
            </span><span>return</span> dt.Rows.Cast<DataRow>().Select(row => <span>new</span><span> DbColumn()
            {
                ColumnID </span>= row.Field<<span>int</span>>(<span>"</span><span>ColumnID</span><span>"</span><span>),
                IsPrimaryKey </span>= row.Field<<span>bool</span>>(<span>"</span><span>IsPrimaryKey</span><span>"</span><span>),
                ColumnName </span>= row.Field<<span>string</span>>(<span>"</span><span>ColumnName</span><span>"</span><span>),
                ColumnType </span>= row.Field<<span>string</span>>(<span>"</span><span>ColumnType</span><span>"</span><span>),
                IsIdentity </span>= row.Field<<span>bool</span>>(<span>"</span><span>IsIdentity</span><span>"</span><span>),
                IsNullable </span>= row.Field<<span>bool</span>>(<span>"</span><span>IsNullable</span><span>"</span><span>),
                ByteLength </span>= row.Field<<span>int</span>>(<span>"</span><span>ByteLength</span><span>"</span><span>),
                CharLength </span>= row.Field<<span>int</span>>(<span>"</span><span>CharLength</span><span>"</span><span>),
                Scale </span>= row.Field<<span>int</span>>(<span>"</span><span>Scale</span><span>"</span><span>),
                Remark </span>= row[<span>"</span><span>Remark</span><span>"</span><span>].ToString()
            }).ToList();
        }

        </span><span>#endregion</span>     


        <span>#region</span> GetDataTable
        
        <span>public</span> <span>static</span> DataTable GetDataTable(<span>string</span> connectionString, <span>string</span> commandText, <span>params</span><span> SqlParameter[] parms)
        {
            </span><span>using</span> (SqlConnection connection = <span>new</span><span> SqlConnection(connectionString))
            {
                SqlCommand command </span>=<span> connection.CreateCommand();
                command.CommandText </span>=<span> commandText;
                command.Parameters.AddRange(parms);
                SqlDataAdapter adapter </span>= <span>new</span><span> SqlDataAdapter(command);

                DataTable dt </span>= <span>new</span><span> DataTable();
                adapter.Fill(dt);

                </span><span>return</span><span> dt;
            }
        }

        </span><span>#endregion</span><span>
    }

    </span><span>#region</span> DbTable
    <span>///</span> <span><summary></span>
    <span>///</span><span> 表结构
    </span><span>///</span> <span></summary></span>
    <span>public</span> <span>sealed</span> <span>class</span><span> DbTable
    {
        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 表名称
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>string</span> TableName { <span>get</span>; <span>set</span><span>; }
        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 表的架构
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>string</span> SchemaName { <span>get</span>; <span>set</span><span>; }
        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 表的记录数
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>int</span> Rows { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 是否含有主键
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>bool</span> HasPrimaryKey { <span>get</span>; <span>set</span><span>; }
    }
    </span><span>#endregion</span>

    <span>#region</span> DbColumn
    <span>///</span> <span><summary></span>
    <span>///</span><span> 表字段结构
    </span><span>///</span> <span></summary></span>
    <span>public</span> <span>sealed</span> <span>class</span><span> DbColumn
    {
        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 字段ID
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>int</span> ColumnID { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 是否主键
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>bool</span> IsPrimaryKey { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 字段名称
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>string</span> ColumnName { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 字段类型
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>string</span> ColumnType { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 数据库类型对应的C#类型
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>string</span><span> CSharpType
        {
            </span><span>get</span><span>
            {
                </span><span>return</span><span> SqlServerDbTypeMap.MapCsharpType(ColumnType);
            }
        }

        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>
        <span>public</span><span> Type CommonType
        {
            </span><span>get</span><span>
            {
                </span><span>return</span><span> SqlServerDbTypeMap.MapCommonType(ColumnType);
            }
        }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 字节长度
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>int</span> ByteLength { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 字符长度
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>int</span> CharLength { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 小数位
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>int</span> Scale { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 是否自增列
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>bool</span> IsIdentity { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 是否允许空
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>bool</span> IsNullable { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></span>
        <span>///</span><span> 描述
        </span><span>///</span> <span></summary></span>
        <span>public</span> <span>string</span> Remark { <span>get</span>; <span>set</span><span>; }
    }
    </span><span>#endregion</span>

    <span>#region</span> SqlServerDbTypeMap

    <span>public</span> <span>class</span><span> SqlServerDbTypeMap
    {
        </span><span>public</span> <span>static</span> <span>string</span> MapCsharpType(<span>string</span><span> dbtype)
        {
            </span><span>if</span> (<span>string</span>.IsNullOrEmpty(dbtype)) <span>return</span><span> dbtype;
            dbtype </span>=<span> dbtype.ToLower();
            </span><span>string</span> csharpType = <span>"</span><span>object</span><span>"</span><span>;
            </span><span>switch</span><span> (dbtype)
            {
                </span><span>case</span> <span>"</span><span>bigint</span><span>"</span>: csharpType = <span>"</span><span>long</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>binary</span><span>"</span>: csharpType = <span>"</span><span>byte[]</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>bit</span><span>"</span>: csharpType = <span>"</span><span>bool</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>char</span><span>"</span>: csharpType = <span>"</span><span>string</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>date</span><span>"</span>: csharpType = <span>"</span><span>DateTime</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>datetime</span><span>"</span>: csharpType = <span>"</span><span>DateTime</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>datetime2</span><span>"</span>: csharpType = <span>"</span><span>DateTime</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>datetimeoffset</span><span>"</span>: csharpType = <span>"</span><span>DateTimeOffset</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>decimal</span><span>"</span>: csharpType = <span>"</span><span>decimal</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>float</span><span>"</span>: csharpType = <span>"</span><span>double</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>image</span><span>"</span>: csharpType = <span>"</span><span>byte[]</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>int</span><span>"</span>: csharpType = <span>"</span><span>int</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>money</span><span>"</span>: csharpType = <span>"</span><span>decimal</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>nchar</span><span>"</span>: csharpType = <span>"</span><span>string</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>ntext</span><span>"</span>: csharpType = <span>"</span><span>string</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>numeric</span><span>"</span>: csharpType = <span>"</span><span>decimal</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>nvarchar</span><span>"</span>: csharpType = <span>"</span><span>string</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>real</span><span>"</span>: csharpType = <span>"</span><span>Single</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>smalldatetime</span><span>"</span>: csharpType = <span>"</span><span>DateTime</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>smallint</span><span>"</span>: csharpType = <span>"</span><span>short</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>smallmoney</span><span>"</span>: csharpType = <span>"</span><span>decimal</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>sql_variant</span><span>"</span>: csharpType = <span>"</span><span>object</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>sysname</span><span>"</span>: csharpType = <span>"</span><span>object</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>text</span><span>"</span>: csharpType = <span>"</span><span>string</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>time</span><span>"</span>: csharpType = <span>"</span><span>TimeSpan</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>timestamp</span><span>"</span>: csharpType = <span>"</span><span>byte[]</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>tinyint</span><span>"</span>: csharpType = <span>"</span><span>byte</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>uniqueidentifier</span><span>"</span>: csharpType = <span>"</span><span>Guid</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>varbinary</span><span>"</span>: csharpType = <span>"</span><span>byte[]</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>varchar</span><span>"</span>: csharpType = <span>"</span><span>string</span><span>"</span>; <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>xml</span><span>"</span>: csharpType = <span>"</span><span>string</span><span>"</span>; <span>break</span><span>;
                </span><span>default</span>: csharpType = <span>"</span><span>object</span><span>"</span>; <span>break</span><span>;
            }
            </span><span>return</span><span> csharpType;
        }
           
        </span><span>public</span> <span>static</span> Type MapCommonType(<span>string</span><span> dbtype)
        {
            </span><span>if</span> (<span>string</span>.IsNullOrEmpty(dbtype)) <span>return</span><span> Type.Missing.GetType();
            dbtype </span>=<span> dbtype.ToLower();
            Type commonType </span>= <span>typeof</span>(<span>object</span><span>);
            </span><span>switch</span><span> (dbtype)
            {
                </span><span>case</span> <span>"</span><span>bigint</span><span>"</span>: commonType = <span>typeof</span>(<span>long</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>binary</span><span>"</span>: commonType = <span>typeof</span>(<span>byte</span>[]); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>bit</span><span>"</span>: commonType = <span>typeof</span>(<span>bool</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>char</span><span>"</span>: commonType = <span>typeof</span>(<span>string</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>date</span><span>"</span>: commonType = <span>typeof</span>(DateTime); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>datetime</span><span>"</span>: commonType = <span>typeof</span>(DateTime); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>datetime2</span><span>"</span>: commonType = <span>typeof</span>(DateTime); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>datetimeoffset</span><span>"</span>: commonType = <span>typeof</span>(DateTimeOffset); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>decimal</span><span>"</span>: commonType = <span>typeof</span>(<span>decimal</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>float</span><span>"</span>: commonType = <span>typeof</span>(<span>double</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>image</span><span>"</span>: commonType = <span>typeof</span>(<span>byte</span>[]); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>int</span><span>"</span>: commonType = <span>typeof</span>(<span>int</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>money</span><span>"</span>: commonType = <span>typeof</span>(<span>decimal</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>nchar</span><span>"</span>: commonType = <span>typeof</span>(<span>string</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>ntext</span><span>"</span>: commonType = <span>typeof</span>(<span>string</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>numeric</span><span>"</span>: commonType = <span>typeof</span>(<span>decimal</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>nvarchar</span><span>"</span>: commonType = <span>typeof</span>(<span>string</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>real</span><span>"</span>: commonType = <span>typeof</span>(Single); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>smalldatetime</span><span>"</span>: commonType = <span>typeof</span>(DateTime); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>smallint</span><span>"</span>: commonType = <span>typeof</span>(<span>short</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>smallmoney</span><span>"</span>: commonType = <span>typeof</span>(<span>decimal</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>sql_variant</span><span>"</span>: commonType = <span>typeof</span>(<span>object</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>sysname</span><span>"</span>: commonType = <span>typeof</span>(<span>object</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>text</span><span>"</span>: commonType = <span>typeof</span>(<span>string</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>time</span><span>"</span>: commonType = <span>typeof</span>(TimeSpan); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>timestamp</span><span>"</span>: commonType = <span>typeof</span>(<span>byte</span>[]); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>tinyint</span><span>"</span>: commonType = <span>typeof</span>(<span>byte</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>uniqueidentifier</span><span>"</span>: commonType = <span>typeof</span>(Guid); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>varbinary</span><span>"</span>: commonType = <span>typeof</span>(<span>byte</span>[]); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>varchar</span><span>"</span>: commonType = <span>typeof</span>(<span>string</span>); <span>break</span><span>;
                </span><span>case</span> <span>"</span><span>xml</span><span>"</span>: commonType = <span>typeof</span>(<span>string</span>); <span>break</span><span>;
                </span><span>default</span>: commonType = <span>typeof</span>(<span>object</span>); <span>break</span><span>;
            }
            </span><span>return</span><span> commonType;
        }
    }
    </span><span>#endregion</span><span>
    

#</span>>

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<span><</span><span>#@ include </span><span>file</span><span>="$(ProjectDir)DbHelper.ttinclude"</span><span>  #</span><span>></span>

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DbHelper相对比较复杂，把一些常用操作进行了简单封装，因此放到一个单独的文件里面进行引用，可以方便的进行复用，这里DbHelper的后缀名使用ttinclude，这里的后缀名可以随便起，按照微软的建议：用于include的文件尽量不要使用.tt做后缀名

良精.Net多风格企业网站管理系统测试版

编码UTF-8 (支持国外服务器)数据库类型 ACCESS 可生成Html静态页面,后台可以模版管理空间必需支持 NET Framework 2.0 环境下运行 (NET Framework 1.1下无法运行)新增功能静态生成风格切换模版管理中英文加繁体三语版本前台访问地址：http://网址/Default.aspx打开首页后会看到下面有后台访问地址用户名admin密码admin后台主

查看详情

在页面底部定义一些常用变量，以方便操作

<#+
    <span>public</span> <span>class</span><span> config
    {
        </span><span>public</span> <span>static</span> <span>readonly</span> <span>string</span> ConnectionString=<span>"</span><span>Data Source=(local);Integrated Security=true;Initial Catalog=Northwind;</span><span>"</span><span>;
        </span><span>public</span> <span>static</span> <span>readonly</span> <span>string</span> DbDatabase=<span>"</span><span>Northwind</span><span>"</span><span>;
        </span><span>public</span> <span>static</span> <span>readonly</span> <span>string</span> TableName=<span>"</span><span>Customers</span><span>"</span><span>;
    }
#</span>>

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这里我们把数据库连接串和数据库、表名字定义一下，方便修改和使用

最后来编写用于实体类生成的代码

<span>//</span><span>------------------------------------------------------------------------------
</span><span>//</span><span> <auto-generated>
</span><span>//</span><span>     此代码由T4模板自动生成
</span><span>//</span><span>       生成时间 <#=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")#> by 懒惰的肥兔
</span><span>//</span><span>     对此文件的更改可能会导致不正确的行为，并且如果
</span><span>//</span><span>     重新生成代码，这些更改将会丢失。
</span><span>//</span><span> </auto-generated>
</span><span>//</span><span>------------------------------------------------------------------------------</span>

<span>using</span><span> System;
</span><span>namespace</span><span> T4ConsoleApplication.Entities
{    

    </span><span>public</span> <span>class</span> <#=config.TableName#><span>
    {
        </span><# <span>foreach</span>(DbColumn column <span>in</span> DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#>

        <span>///</span> <span><summary></span>
        <span>///</span> <span><#=column.Remark#></span>
        <span>///</span> <span></summary></span>        
        <span>public</span> <#= column.CSharpType#><# <span>if</span>(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName#> { <span>get</span>; <span>set</span><span>; }
        </span><#}#><span> 
      
    }
}</span>

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全部完成后我们的Customers.tt文件就编写好了

T4模版引擎之生成数据库实体类 Customers.tt

<#@ template debug="false" hostspecific="false" language="C#" #>
<#@ output extension=".cs" #>
<#@ assembly name="System.Core.dll" #>
<#@ assembly name="System.Data.dll" #>
<#@ assembly name="System.Data.DataSetExtensions.dll" #>
<#@ assembly name="System.Xml.dll" #>
<#@ import namespace="System" #>
<#@ import namespace="System.Xml" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Data" #>
<#@ import namespace="System.Data.SqlClient" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.IO" #>
<#@ include file="$(ProjectDir)DbHelper.ttinclude"  #>
//------------------------------------------------------------------------------
// 
//     此代码由T4模板自动生成
//       生成时间 <#=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")#> by 懒惰的肥兔
//     对此文件的更改可能会导致不正确的行为，并且如果
//     重新生成代码，这些更改将会丢失。
// 
//------------------------------------------------------------------------------

using System;
namespace T4ConsoleApplication.Entities
{    

    public class <#=config.TableName#>
    {
        <# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#>

        /// 
        /// <#=column.Remark#>
        ///         
        public <#= column.CSharpType#><# if(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName#> { get; set; }
        <#}#> 
      
    }
}

<#+
    <span>public</span> <span>class</span><span> config
    {
        </span><span>public</span> <span>static</span> <span>readonly</span> <span>string</span> ConnectionString=<span>"</span><span>Data Source=(local);Integrated Security=true;Initial Catalog=Northwind;</span><span>"</span><span>;
        </span><span>public</span> <span>static</span> <span>readonly</span> <span>string</span> DbDatabase=<span>"</span><span>Northwind</span><span>"</span><span>;
        </span><span>public</span> <span>static</span> <span>readonly</span> <span>string</span> TableName=<span>"</span><span>Customers</span><span>"</span><span>;
    }
#</span>>

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进行保存后会自动生成Customers.cs文件

T4模版引擎之生成数据库实体类 Customers.cs

<span>//</span><span>------------------------------------------------------------------------------
</span><span>//</span><span> <auto-generated>
</span><span>//</span><span>     此代码由T4模板自动生成
</span><span>//</span><span>       生成时间 2012-07-18 17:51:26 by 懒惰的肥兔
</span><span>//</span><span>     对此文件的更改可能会导致不正确的行为，并且如果
</span><span>//</span><span>     重新生成代码，这些更改将会丢失。
</span><span>//</span><span> </auto-generated>
</span><span>//</span><span>------------------------------------------------------------------------------</span>

<span>using</span><span> System;
</span><span>namespace</span><span> T4ConsoleApplication.Entities
{    

    </span><span>public</span> <span>class</span><span> Customers
    {
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> CustomerID { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> CompanyName { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> ContactName { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> ContactTitle { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> Address { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> City { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> Region { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> PostalCode { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> Country { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> Phone { <span>get</span>; <span>set</span><span>; }
        
        </span><span>///</span> <span><summary></span>
        <span>///</span> 
        <span>///</span> <span></summary></span>        
        <span>public</span> <span>string</span> Fax { <span>get</span>; <span>set</span><span>; }
         
      
    }
}</span>

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　　至此完整演示了怎样一步步根据数据库生成实体类的操作，是不是很简单，如对语法和操作不理解的地方可以参考T4模版引擎之基础入门，稍微用心研究下，轻松打造属于自己的代码生成器。

通过单个T4模板生成多个文件，以及自动生成整个数据库的所有实体类，敬请期待

　　下班了，拍拍屁股走人。。。

源码：T4ConsoleApplication.rar