Вот пользовательская оболочка, которую я сделал для System.Data.Linq. Он содержит метод find, поэтому вместо вашего кода:
var myContext = new DataContext();
var product = context.Products.Where(p => p.Id == productId).SingleOrDefault();
Вы можете сделать это
var myContext = new DataContext();
var product = context.Products.Find(productId); //(assuming productId is your primary key)
Вы можете взять приведенный ниже код и выполнить любые пользовательские изменения, которые вы хотите установить product.Context, но это пример изменения DataContext.
Я также сделал методы сохранения и удаления. Вы заметите, что я перезаписываю запись, даже если она передается. Я делаю это, потому что запись может отделяться от контекста и не обновляться. Если кому-то нужен полный код, я могу опубликовать ссылку на github.
public abstract class DbContext : IDisposable
{
#region Properties
private string _connectionString { get; set; }
private DataContext _context { get; set; }
#endregion
#region Constructor
public DbContext(string connectionString)
{
_connectionString = connectionString;
_context = new DataContext(_connectionString);
Initialized(_context);
}
public DbContext(string server, string database, string userID, string password)
{
_connectionString = string.Format(
"Server={0};Database={1};User Id={2};Password={3};MultipleActiveResultSets=true",
server,
database,
userID,
password);
_context = new DataContext(_connectionString);
Initialized(_context);
}
#endregion
#region Methods
/// <summary>
/// Is used to get the contents of a Sql Server Table.
/// </summary>
/// <typeparam name="TEntity">Type</typeparam>
/// <returns>Table</returns>
public Table<TEntity> GetTable<TEntity, TPKType>()
where TEntity : DbTableEquatable<IDbTableEquatable<TPKType>>
where TPKType : struct
{
return _context.GetTable<TEntity>();
}
/// <summary>
/// Is used to get the contents of a Sql Server Table.
/// </summary>
/// <typeparam name="TEntity">Type</typeparam>
/// <returns>Table</returns>
public Table<TEntity> GetTable<TEntity>()
where TEntity : DbTableEquatable<IDbTableEquatable<long>>
{
return GetTable<TEntity, long>();
}
protected virtual void Initialized(DataContext context) { }
/// <summary>
/// Saves the changes to the database. In order to save the table must inherit from DbTableEquatable
/// and be a type of IDbTableEquatable and the Primary Key Type must be a C# Structure
/// </summary>
/// <typeparam name="TEntity">Record Type</typeparam>
/// <typeparam name="TPKType">Primary Key Type</typeparam>
/// <param name="entity">Record</param>
public virtual void SaveChanges<TEntity, TPKType>(TEntity entity)
where TEntity : DbTableEquatable<IDbTableEquatable<TPKType>>
where TPKType : struct
{
var changedList = _context.GetTable<TEntity>();
var ID = entity.GetType().GetProperty("ID").GetValue(entity);
_preprocessSave<TEntity, TPKType>(entity);
// Save changes
if (Convert.ToInt64(ID) == 0)
{
// Insert
// If No ID we need to insert on submit
_context.GetTable<TEntity>().InsertOnSubmit((TEntity)entity);
_context.SubmitChanges();
}
else
{
// Update
var item = changedList.Where(w => w.Equals(entity)).FirstOrDefault();
ReflectionManager.SetValuesWithSkip(entity, item, "ID");
_context.SubmitChanges();
}
Refresh();
}
/// <summary>
/// Saves the changes to the database. In order to save the Table the Record is from must inherit from DbTableEquatable
/// and be a type of IDbTableEquatable and the Primary Key Type must be a C# Structure
/// </summary>
/// <typeparam name="TEntity">Record Type</typeparam>
/// <param name="entity">Record</param>
public virtual void SaveChanges<TEntity>(TEntity entity)
where TEntity : DbTableEquatable<IDbTableEquatable<long>>
{
SaveChanges<TEntity, long>(entity);
}
/// <summary>
/// Saves any non committed changes to the database
/// </summary>
public void SaveChanges()
{
_context.SubmitChanges();
Refresh();
}
/// <summary>
/// Marks the record as delete and will be deleted when saved
/// </summary>
/// <typeparam name="TEntity">Record Type</typeparam>
/// <typeparam name="TPKType">Primary Key Type</typeparam>
/// <param name="entity">Record</param>
public virtual void DeleteOnSave<TEntity, TPKType>(TEntity entity)
where TEntity : DbTableEquatable<IDbTableEquatable<TPKType>>
where TPKType : struct
{
var item = _context.GetTable<TEntity>().Where(w => w.Equals(entity)).FirstOrDefault();
_context.GetTable<TEntity>().DeleteOnSubmit((TEntity)item);
}
/// <summary>
/// Marks the record as delete and will be deleted when saved
/// </summary>
/// <typeparam name="TEntity">Record Type</typeparam>
/// <param name="entity">Record</param>
public virtual void DeleteOnSave<TEntity>(TEntity entity)
where TEntity : DbTableEquatable<IDbTableEquatable<long>>
{
DeleteOnSave<TEntity, long>(entity);
}
protected virtual void _preprocessSave<TEntity, TPKType>(TEntity entity)
where TEntity : DbTableEquatable<IDbTableEquatable<TPKType>>
where TPKType : struct
{
}
protected virtual void _preprocessSave<TEntity>(TEntity entity)
where TEntity : DbTableEquatable<IDbTableEquatable<long>>
{
_preprocessSave<TEntity, long>(entity);
}
public void Dispose()
{
_connectionString = "";
_context.Dispose();
_context = null;
}
public virtual void Refresh<TEntity>(RefreshMode mode, TEntity entity) where TEntity : class
{
_context.Refresh(RefreshMode.OverwriteCurrentValues, entity);
}
public virtual void Refresh()
{
_context = new DataContext(_connectionString);
}
public virtual void Refresh<TEntity>(RefreshMode mode, params TEntity[] entities) where TEntity : class
{
_context.Refresh(RefreshMode.OverwriteCurrentValues, entities);
}
public virtual void Refresh<TEntity>(RefreshMode mode, IEnumerable<TEntity> entities) where TEntity : class
{
_context.Refresh(RefreshMode.OverwriteCurrentValues, entities);
}
#endregion
}
Extenstions
public static class Extension
{
public static TEntity Find<TEntity, TPKType>(this Table<TEntity> table, TPKType ID, string pkName = "ID")
where TEntity : DbTableEquatable<IDbTableEquatable<TPKType>>
where TPKType : struct
{
TEntity copy = Activator.CreateInstance<TEntity>();
// set value through reflection
copy.GetType().GetProperty(pkName).SetValue(copy, ID, null);
return (TEntity)table.Where(w => w.Equals(copy)).FirstOrDefault();
}
public static TEntity Find<TEntity>(this Table<TEntity> table, long ID, string pkName = "ID")
where TEntity : DbTableEquatable<IDbTableEquatable<long>>
{
TEntity copy = Activator.CreateInstance<TEntity>();
// set value through reflection
copy.GetType().GetProperty(pkName).SetValue(copy, ID, null);
return (TEntity)table.Where(w => w.Equals(copy)).FirstOrDefault();
}
}
}
Интерфейс / Абстракция
/// <summary>
/// This Class Assumes the type T has a property called ID. MUST be
/// used with IDbEquatable
/// </summary>
/// <typeparam name="T">Class Type</typeparam>
public abstract class DbTableEquatable<T> : IEquatable<T> where T : class
{
public bool Equals(T other)
{
//Check whether the compared object is null.
if (Object.ReferenceEquals(other, null))
{
return false;
}
//Check whether the compared object references the same data.
if (Object.ReferenceEquals(this, other))
{
return true;
}
return ((dynamic)other).ID == ((dynamic)this).ID;
}
}
/// <summary>
/// Needs to be inherited from in order for Ion.Data.Linq functions to work
/// </summary>
/// <typeparam name="T">Primary Key Type</typeparam>
public interface IDbTableEquatable<T>
{
T ID { get; set; }
}
вот таблица реализации
[Table(Name = "Crews")]
public class Crew : DbTableEquatable<IDbTableEquatable<long>>, IDbTableEquatable<long>
{
[Column(IsPrimaryKey = true, DbType = "Bigint NOT NULL IDENTITY", AutoSync = AutoSync.OnInsert, IsDbGenerated = true)]
public long ID { get; set; }
[Column]
public string Alias { get; set; }
[Column]
public string DefaultForeground { get; set; }
[Column]
public string DefaultBackground { get; set; }
[Column]
public string AccountEmailAddress { get; set; }
[Column]
public long? CrewLeaderEmployeeID { get; set; }
[Column]
public string Comments { get; set; }
[Column]
public string Password { get; set; }
[Column]
public string PrivateICSLink { get; set; }
[Column]
public string PrivateXMLLink { get; set; }
}