c# - 简单 POCO 的简单 T4 生成

Question

<分区>

Answer 1

我一直想回答这个问题，但一直很忙。

我创建了一个关于如何读取数据库模式并从中生成类和属性的简单示例。

基本上，您应该能够将其剪切并粘贴到 TT 文件中(参见 Oleg Sychs blog 如何开始)，更新连接字符串并保存以执行模板。

我并不是说这是一个完整的示例，但它可以作为您的起点:

  <#@ template   language    = "C#"                           #>
  <#@ assembly   name        = "Microsoft.CSharp"             #>
  <#@ assembly   name        = "System.Core"                  #>
  <#@ assembly   name        = "System.Data"                  #>
  <#@ import     namespace   = "System.Collections.Generic"   #>
  <#@ import     namespace   = "System.Dynamic"               #>
  <#@ import     namespace   = "System.Linq"                  #>
  <#@ import     namespace   = "System.Data.SqlClient"        #>

  <#
     var namespaceName    = "Poco2";
     // Update the connection string to something appropriate
     var connectionString = @"Data Source=localhost\SQLExpress;Initial Catalog=MyTest;Integrated Security=True";
  #>

  <#
     using (var db = new SqlConnection (connectionString))
     using (var cmd = db.CreateCommand ())
     {
        db.Open();
        var tables              = ReadRows (cmd, "SELECT * FROM sys.tables").ToArray ();

        var columns             = ReadRows (cmd, "SELECT * FROM sys.columns").ToLookup (k => k.object_id);

        var indexes             = ReadRows (cmd, "SELECT * FROM sys.indexes").ToLookup (k => k.object_id);
        var indexColumns        = ReadRows (cmd, "SELECT * FROM sys.index_columns").ToLookup (k => k.object_id);

        var foreignKeys         = ReadRows (cmd, "SELECT * FROM sys.foreign_keys").ToArray ();
        var foreignKeyColumns   = ReadRows (cmd, "SELECT * FROM sys.foreign_key_columns").ToArray ();
  #>
  namespace <#=namespaceName#>
  {
     using System;
     using System.Data.Linq.Mapping;

  <#
        foreach (var table in tables)
        {         
  #>
     [Table]
     partial class <#=table.name#>
     {
  <#
           IEnumerable<dynamic> tc = columns[table.object_id];
           var tableColumns = tc.OrderBy (r => r.column_id).ToArray ();          

           IEnumerable<dynamic> ti = indexes[table.object_id];
           var tableIndexes = ti.ToArray ();          

           var primaryKeyIndex = tableIndexes.FirstOrDefault (i => i.is_primary_key);
           var primaryKeyColumns = new Dictionary<dynamic, dynamic> ();
           if (primaryKeyIndex != null)
           {
              IEnumerable<dynamic> pc = indexColumns[table.object_id];
              primaryKeyColumns = pc
                 .Where (c => c.index_id == primaryKeyIndex.index_id)
                 .ToDictionary (c => c.column_id, c => c.key_ordinal)
                 ;
           }

           foreach (var tableColumn in tableColumns)
           {
              var type = MapToType (tableColumn.user_type_id, tableColumn.max_length, tableColumn.is_nullable);

  #>
        [Column (IsPrimaryKey = <#=primaryKeyColumns.ContainsKey (tableColumn.column_id) ? "true" : "false"#>)]
        public <#=type#> <#=tableColumn.name#> {get;set;}

  <#
           }
  #>

     }
  <#
        }
  #>
  }
  <#
     }
  #>

  <#+

     struct DataType
     {     
        public readonly int     SizeOf;
        public readonly string  SingularType;
        public readonly string  PluralType;

        public DataType (
           int sizeOf,
           string singularType,
           string pluralType = null
           )
        {
           SizeOf         = sizeOf;
           SingularType   = singularType;
           PluralType     = pluralType ?? (singularType + "[]");
        }

     }
     static Dictionary<int, DataType> dataTypes = new Dictionary<int, DataType>
        {
           {61   , new DataType (8,  "DateTime"            )},
           {127  , new DataType (8,  "long"                )},
           {165  , new DataType (1,  "byte"                )},
           {231  , new DataType (2,  "char"    ,  "string" )},
        };

     static string MapToType (int typeId, int maxLength, bool isNullable)
     {
        DataType dataType;

        if (dataTypes.TryGetValue (typeId, out dataType))
        {
           var length = maxLength > 0 ? (maxLength / dataType.SizeOf) : int.MaxValue;
           if (length > 1)
           {
              return dataType.PluralType;
           }
           else
           {
              return dataType.SingularType + (isNullable ? "?" : "");
           }
        }
        else
        {
           return "UnknownType_"+ typeId;
        }
     }

     static IEnumerable<dynamic> ReadRows (SqlCommand command, string sql)
     {
        command.CommandText = sql ?? "";

        using (var reader = command.ExecuteReader())
        {
           while (reader.Read())
           {
              var dyn = new ExpandoObject ();
              IDictionary<string, object> dic = dyn;

              for (var iter = 0; iter < reader.FieldCount; ++iter)
              {
                    dic[reader.GetName(iter) ?? ""] = reader.GetValue(iter);
              }

              yield return dyn;
           }

        }
     }


  #>