增加几个entity framework 的函数 (记录备忘)[转]

public static class DatabaseExtensions
{
public static DataTable SqlQueryForDataTatable(this Database db, string sql, params SqlParameter[] parameters)
{

SqlConnection conn = new System.Data.SqlClient.SqlConnection();
conn.ConnectionString = db.Connection.ConnectionString;
if (conn.State != ConnectionState.Open)
{
conn.Open();
}
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = sql;

if (parameters.Length > 0)
{
foreach (var item in parameters)
{
cmd.Parameters.Add(item);
}
}

SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataTable table = new DataTable();
adapter.Fill(table);
return table;
}

public static IEnumerable SqlQueryForDynamic(this Database db, string sql, params object[] parameters)
{
IDbConnection defaultConn = new System.Data.SqlClient.SqlConnection();
return SqlQueryForDynamicOtherDB(db, sql, defaultConn, parameters);
}

public static IEnumerable SqlQueryForDynamicOtherDB(this
Database db, string sql, IDbConnection conn, params object[] parameters)
{
conn.ConnectionString = db.Connection.ConnectionString;
if (conn.State != ConnectionState.Open)
{
conn.Open();
}

IDbCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;

IDataReader dataReader = cmd.ExecuteReader();

if (!dataReader.Read())
{
return null; //无结果返回Null
}

#region 构建动态字段

TypeBuilder builder = DatabaseExtensions.CreateTypeBuilder(
"EF_DynamicModelAssembly",
"DynamicModule",
"DynamicType");

int fieldCount = dataReader.FieldCount;
for (int i = 0; i < fieldCount; i++)
{
//dic.Add(i, dataReader.GetName(i));

//Type type = dataReader.GetFieldType(i);

DatabaseExtensions.CreateAutoImplementedProperty(
builder,
dataReader.GetName(i),
dataReader.GetFieldType(i));
}

#endregion

dataReader.Close();
dataReader.Dispose();
cmd.Dispose();
conn.Close();
conn.Dispose();

Type returnType = builder.CreateType();

if (parameters != null)
{
return db.SqlQuery(returnType, sql, parameters);
}
else
{
return db.SqlQuery(returnType, sql);
}
}

public static TypeBuilder CreateTypeBuilder(string assemblyName, string moduleName, string typeName)
{
TypeBuilder typeBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(
new AssemblyName(assemblyName),
AssemblyBuilderAccess.Run).DefineDynamicModule(moduleName).DefineType(typeName,
TypeAttributes.Public);
typeBuilder.DefineDefaultConstructor(MethodAttributes.Public);
return typeBuilder;
}

public static void CreateAutoImplementedProperty(TypeBuilder builder, string propertyName, Type propertyType)
{
const string PrivateFieldPrefix = "m_";
const string GetterPrefix = "get_";
const string SetterPrefix = "set_";

// Generate the field.
FieldBuilder fieldBuilder = builder.DefineField(
string.Concat(
PrivateFieldPrefix, propertyName),
propertyType,
FieldAttributes.Private);

// Generate the property
PropertyBuilder propertyBuilder = builder.DefineProperty(
propertyName,
System.Reflection.PropertyAttributes.HasDefault,
propertyType, null);

// Property getter and setter attributes.
MethodAttributes propertyMethodAttributes = MethodAttributes.Public
| MethodAttributes.SpecialName
| MethodAttributes.HideBySig;

// Define the getter method.
MethodBuilder getterMethod = builder.DefineMethod(
string.Concat(
GetterPrefix, propertyName),
propertyMethodAttributes,
propertyType,
Type.EmptyTypes);

// Emit the IL code.
// ldarg.0
// ldfld,_field
// ret
ILGenerator getterILCode = getterMethod.GetILGenerator();
getterILCode.Emit(OpCodes.Ldarg_0);
getterILCode.Emit(OpCodes.Ldfld, fieldBuilder);
getterILCode.Emit(OpCodes.Ret);

// Define the setter method.
MethodBuilder setterMethod = builder.DefineMethod(
string.Concat(SetterPrefix, propertyName),
propertyMethodAttributes,
null,
new Type[] { propertyType });

// Emit the IL code.
// ldarg.0
// ldarg.1
// stfld,_field
// ret
ILGenerator setterILCode = setterMethod.GetILGenerator();
setterILCode.Emit(OpCodes.Ldarg_0);
setterILCode.Emit(OpCodes.Ldarg_1);
setterILCode.Emit(OpCodes.Stfld, fieldBuilder);
setterILCode.Emit(OpCodes.Ret);

propertyBuilder.SetGetMethod(getterMethod);
propertyBuilder.SetSetMethod(setterMethod);
}

}