#region License
/*
* Copyright 2002-2006 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#endregion
using System.Data.Common;
using Spring.Data.Generic;
namespace Spring.DataQuickStart.Dao.GenericTemplate{
/// <summary>
/// A simple DAO that uses Generic.AdoTemplate CommandCallback functionality
/// </summary>
public class CommandCallbackDao : AdoDaoSupport
{
private string cmdText = "select count(*) from Customers where PostalCode = @PostalCode";
/// <summary>
/// Finds the number of customers with the given postal code.
/// </summary>
/// <param name="postalCode">The postal code.</param>
/// <returns>Number of customers with the given postal code.</returns>
public virtual int FindCountWithPostalCodeWithDelegate(string postalCode)
{
// Using anonymous delegates allows you to easily reference the
// surrounding parameters for use with the DbCommand processing.
return AdoTemplate.Execute<int>(delegate(DbCommand command)
{
// Do whatever you like with the DbCommand... downcast to get
// provider specific funtionality if necesary.
command.CommandText = cmdText;
DbParameter p = command.CreateParameter();
p.ParameterName = "@PostalCode";
p.Value = postalCode;
command.Parameters.Add(p);
return (int)command.ExecuteScalar();
});
}
public virtual int FindCountWithPostalCode(string postalCode)
{
// Type inference allows you not to explicitly write .Execute<ResultObject>
return AdoTemplate.Execute(new PostalCodeCommandCallback<ResultObject>(postalCode)).count;
}
// Note that you can not use System.Array, System.Delegate, System.Enum,
// System.ValueType or object in the constraint. for this example that returns just
// an integer, a simple 'ResultObject' type is used.
// You code would generally have a return object more complex than an 'int'.
/// <summary>
/// A callback implementation that returns a 'ResultObject' containing a the count
/// of customers with a specific zip code.
/// </summary>
/// <typeparam name="T"></typeparam>
private class PostalCodeCommandCallback<T> : ICommandCallback<T> where T : ResultObject, new()
{
private string postalCode;
public PostalCodeCommandCallback(string postalCode)
{
this.postalCode = postalCode;
}
public T DoInCommand(DbCommand command)
{
T resultObject = new T();
DbParameter p = command.CreateParameter();
p.ParameterName = "@PostalCode";
p.Value = postalCode;
command.Parameters.Add(p);
resultObject.count = (int)command.ExecuteScalar();
return resultObject;
}
}
}
/// <summary>
/// Helper class for returning simple integer value via generic class.
/// </summary>
public class ResultObject
{
public int count;
}
}
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