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/// <summary>
/// Reads database schema from query, generates assembly in the memory, and returns dynamic object
/// </summary>
public static System.Collections.IEnumerable DynamicSqlQuery(this Database database, string sql, params object[] parameters)
{
TypeBuilder builder = DynamicMapper.createTypeBuilder(
"MyDynamicAssembly", "MyDynamicModule", "MyDynamicType");
using (System.Data.IDbCommand command = database.Connection.CreateCommand())
{
try
{
database.Connection.Open();
command.CommandText = sql;
command.CommandTimeout = command.Connection.ConnectionTimeout;
foreach (var param in parameters)
{
command.Parameters.Add(param);
}
using (System.Data.IDataReader reader = command.ExecuteReader())
{
var schema = reader.GetSchemaTable();
foreach (System.Data.DataRow row in schema.Rows)
{
string name = (string)row["ColumnName"];
Type type = (Type)row["DataType"];
DynamicMapper.createAutoImplementedProperty(builder, name, type);
}
}
}
finally
{
database.Connection.Close();
command.Parameters.Clear();
}
}
Type resultType = builder.CreateType();
return database.SqlQuery(resultType, sql, parameters);
}
private 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;
}
private 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, 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);
}
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