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T4模版引擎之生成数据库实体类

WBOY
Release： 2016-06-07 15:10:53
Original
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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

  1. 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

    T4模版引擎之生成数据库实体类

  2. 修改输出文件扩展名为.cs 

    <span><span>#@ output </span><span>extension</span><span>=".cs"</span><span> #</span><span>></span></span>
    Copy after login
  3. 添加常用的程序集和命名空间引用 

    <span><span>#@ assembly </span><span>name</span><span>="System.Core.dll"</span><span> #</span><span>></span>
<span><span>#@ assembly </span><span>name</span><span>="System.Data.dll"</span><span> #</span><span>></span>
<span><span>#@ assembly </span><span>name</span><span>="System.Data.DataSetExtensions.dll"</span><span> #</span><span>></span>
<span><span>#@ assembly </span><span>name</span><span>="System.Xml.dll"</span><span> #</span><span>></span>
<span><span>#@ import </span><span>namespace</span><span>="System"</span><span> #</span><span>></span>
<span><span>#@ import </span><span>namespace</span><span>="System.Xml"</span><span> #</span><span>></span>
<span><span>#@ import </span><span>namespace</span><span>="System.Linq"</span><span> #</span><span>></span>
<span><span>#@ import </span><span>namespace</span><span>="System.Data"</span><span> #</span><span>></span>
<span><span>#@ import </span><span>namespace</span><span>="System.Data.SqlClient"</span><span> #</span><span>></span>
<span><span>#@ import </span><span>namespace</span><span>="System.Collections.Generic"</span><span> #</span><span>></span>
<span><span>#@ import </span><span>namespace</span><span>="System.IO"</span><span> #</span><span>></span></span></span></span></span></span></span></span></span></span></span></span>
    Copy after login
  4. 添加数据库操作DbHelper引用

    T4模版引擎之生成数据库实体类T4模版引擎之生成数据库实体类DbHelper.ttinclude 

    public <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<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.Fieldstring</datarow></span>>(<span>"</span><span>tablename</span><span>"</span><span>),
                SchemaName </span>= row.Fieldstring>(<span>"</span><span>schemname</span><span>"</span><span>),
                Rows </span>= row.Fieldint>(<span>"</span><span>rows</span><span>"</span><span>),
                HasPrimaryKey </span>= row.Fieldbool>(<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.Fieldint>(<span>"</span><span>ColumnID</span><span>"</span><span>),
                IsPrimaryKey </span>= row.Fieldbool>(<span>"</span><span>IsPrimaryKey</span><span>"</span><span>),
                ColumnName </span>= row.Fieldstring>(<span>"</span><span>ColumnName</span><span>"</span><span>),
                ColumnType </span>= row.Fieldstring>(<span>"</span><span>ColumnType</span><span>"</span><span>),
                IsIdentity </span>= row.Fieldbool>(<span>"</span><span>IsIdentity</span><span>"</span><span>),
                IsNullable </span>= row.Fieldbool>(<span>"</span><span>IsNullable</span><span>"</span><span>),
                ByteLength </span>= row.Fieldint>(<span>"</span><span>ByteLength</span><span>"</span><span>),
                CharLength </span>= row.Fieldint>(<span>"</span><span>CharLength</span><span>"</span><span>),
                Scale </span>= row.Fieldint>(<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></summary></span>
    <span>///</span><span> 表结构
    </span><span>///</span> <span></span>
    <span>public</span> <span>sealed</span> <span>class</span><span> DbTable
    {
        </span><span>///</span> <span><summary></summary></span>
        <span>///</span><span> 表名称
        </span><span>///</span> <span></span>
        <span>public</span> <span>string</span> TableName { <span>get</span>; <span>set</span><span>; }
        </span><span>///</span> <span><summary></summary></span>
        <span>///</span><span> 表的架构
        </span><span>///</span> <span></span>
        <span>public</span> <span>string</span> SchemaName { <span>get</span>; <span>set</span><span>; }
        </span><span>///</span> <span><summary></summary></span>
        <span>///</span><span> 表的记录数
        </span><span>///</span> <span></span>
        <span>public</span> <span>int</span> Rows { <span>get</span>; <span>set</span><span>; }

        </span><span>///</span> <span><summary></summary></span>
        <span>///</span><span> 是否含有主键
        </span><span>///</span> <span></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></summary></span>
    <span>///</span><span> 表字段结构
    </span><span>///</span> <span></span>
    <span>public</span> <span>sealed</span> <span>class</span><span> DbColumn
    {
        </span><span>///</span> <span><summary></summary></span>
        <span>///</span><span> 字段ID
        </span><span>///</span> <span></span>
        <span>public</span> <span>int</span> ColumnID { <span>get</span>; <span>set</span><span>; }

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

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

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

        </span><span>///</span> <span><summary></summary></span>
        <span>///</span><span> 数据库类型对应的C#类型
        </span><span>///</span> <span></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></summary></span>
        <span>///</span> 
        <span>///</span> <span></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></summary></span>
        <span>///</span><span> 字节长度
        </span><span>///</span> <span></span>
        <span>public</span> <span>int</span> ByteLength { <span>get</span>; <span>set</span><span>; }

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

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

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

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

        </span><span>///</span> <span><summary></summary></span>
        <span>///</span><span> 描述
        </span><span>///</span> <span></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>></datarow></dbcolumn></dbtable>
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    <span><span>#@ include </span><span>file</span><span>="$(ProjectDir)DbHelper.ttinclude"</span><span>  #</span><span>></span></span>
    Copy after login

    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

  5. 在页面底部定义一些常用变量，以方便操作 

    public <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>>
    Copy after login

    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

  6. 最后来编写用于实体类生成的代码 

    <span>//</span><span>------------------------------------------------------------------------------
</span><span>//</span><span> <auto-generated>
</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  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> 
</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>
    {
        </span>foreach(DbColumn column <span>in</span> DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#>

        <span>///</span> <span><summary></summary></span>
        <span>///</span> <span></span>
        <span>///</span> <span></span>        
        <span>public</span> if(column.CommonType.IsValueType && column.IsNullable){#>?  { <span>get</span>; <span>set</span><span>; }
        </span><span> 
      
    }
}</span>
    Copy after login
  7. 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T4模版引擎之生成数据库实体类Customers.tt 

    "false" hostspecific="false" language="C#" #>
".cs" #>
"System.Core.dll" #>
"System.Data.dll" #>
"System.Data.DataSetExtensions.dll" #>
"System.Xml.dll" #>
namespace="System" #>
namespace="System.Xml" #>
namespace="System.Linq" #>
namespace="System.Data" #>
namespace="System.Data.SqlClient" #>
namespace="System.Collections.Generic" #>
namespace="System.IO" #>
"$(ProjectDir)DbHelper.ttinclude"  #>
//------------------------------------------------------------------------------
// 
//     此代码由T4模板自动生成
//       生成时间  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 
    {
        foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#>

        /// 
        /// 
        ///         
        public if(column.CommonType.IsValueType && column.IsNullable){#>?  { get; set; }
         
      
    }
}

public <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>>
    Copy after login

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

     

    　　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

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