QueryOver是否有查詢生成器或擴展點，就像LINQ一樣？

Question

我正在嘗試使用與Query<T>()內QueryOver<T>()內使用計算的屬性。當使用LINQ查詢時，我可以使用自定義的DefaultLinqToHqlGeneratorsRegistry註冊自定義生成器。這適用於calculated properties from an expression，因此代碼不會重複。

我似乎無法找到爲QueryOver API註冊自定義生成器的擴展點。它存在嗎？

我想不是必須複製原始SQL字符串（Map(x => x.Prop).Formula("query").LazyLoad().Access.ReadOnly()）內部的計算屬性邏輯。這意味着兩倍的邏輯和兩倍的測試。

根據我所看到的source，QueryOver API使用Criterion作爲其基礎...直接轉換爲原始SQL而不是HQL。

Answer 1

LINQ和QueryOver採取不同的路徑到SQL：

QueryOver -> Expression -> Criteria \ 
Linq  -> LinqParser -> Hql  --> Sql 

的標準有NHibernate.Impl.ExpressionProcessor.RegisterCustomMethodCall(...);這可能是你想要的。

一個簡單的例子：

public static class QueryOverExtensions 
{ 
    public static void Register() 
    { 
     ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Day(default(DateTime)), QueryOverExtensions.ProcessDay); 
     ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Month(default(DateTime)), QueryOverExtensions.ProcessMonth); 
     ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Year(default(DateTime)), QueryOverExtensions.ProcessYear); 
    } 

    public static Int32 Day(this DateTime dateTimeProperty) 
    { 
     return (dateTimeProperty.Day); 
    } 

    public static Int32 Month(this DateTime dateTimeProperty) 
    { 
     return (dateTimeProperty.Month); 
    } 

    public static Int32 Year(this DateTime dateTimeProperty) 
    { 
     return (dateTimeProperty.Year); 
    } 

    private static IProjection ProcessDay(MethodCallExpression methodCallExpression) 
    { 
     IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection(); 
     return (Projections.SqlFunction("day", NHibernateUtil.Int32, property)); 
    } 

    private static IProjection ProcessMonth(MethodCallExpression methodCallExpression) 
    { 
     IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection(); 
     return (Projections.SqlFunction("month", NHibernateUtil.Int32, property)); 
    } 

    private static IProjection ProcessYear(MethodCallExpression methodCallExpression) 
    { 
     IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection(); 
     return (Projections.SqlFunction("year", NHibernateUtil.Int32, property)); 
    } 
} 

不要忘記調用註冊（）。之後，你可以使用它像這樣：

session.QueryOver<Order>().Where(o => o.Date.Month() == DateTime.Today.Month).List(); 

Answer 2

一個簡單的例子：

public static class QueryOverExtensions 
{ 
    public static void Register() 
    { 
     ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Day(default(DateTime)), QueryOverExtensions.ProcessDay); 
     ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Month(default(DateTime)), QueryOverExtensions.ProcessMonth); 
     ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Year(default(DateTime)), QueryOverExtensions.ProcessYear); 
    } 

    public static Int32 Day(this DateTime dateTimeProperty) 
    { 
     return (dateTimeProperty.Day); 
    } 

    public static Int32 Month(this DateTime dateTimeProperty) 
    { 
     return (dateTimeProperty.Month); 
    } 

    public static Int32 Year(this DateTime dateTimeProperty) 
    { 
     return (dateTimeProperty.Year); 
    } 

    private static IProjection ProcessDay(MethodCallExpression methodCallExpression) 
    { 
     IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection(); 
     return (Projections.SqlFunction("day", NHibernateUtil.Int32, property)); 
    } 

    private static IProjection ProcessMonth(MethodCallExpression methodCallExpression) 
    { 
     IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection(); 
     return (Projections.SqlFunction("month", NHibernateUtil.Int32, property)); 
    } 

    private static IProjection ProcessYear(MethodCallExpression methodCallExpression) 
    { 
     IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection(); 
     return (Projections.SqlFunction("year", NHibernateUtil.Int32, property)); 
    } 
} 

不要忘記調用註冊（）。之後，你可以這樣使用它：

session.QueryOver<Order>().Where(o => o.Date.Month() == DateTime.Today.Month).List();