public IQueryable <T> Include <TProperty>(IQueryable <T> query, Expression <Func <T, TProperty> > expression)
{
ExpressionWrapper <T, M> wrapper = new ExpressionWrapper <T, M>();
LambdaExpression newExpression = (LambdaExpression)wrapper.Visit(expression);
var propertyType = newExpression.Type.GetGenericArguments()[1];
var queryable = query.Unwrap <T, M>();
queryable = (IQueryable <M>)InnerContext.GetType().GetMethod("Include").MakeGenericMethod(propertyType).Invoke(InnerContext, new object[] { queryable, newExpression });
return(queryable.Wrap <T, M>());
}
public static IQueryable <M> Unwrap <T, M>(this IQueryable <T> queryable)
where T : IEntity
where M : IEntity, T
{
WrappedQueryable <T, M> wrapped = queryable as WrappedQueryable <T, M>;
if (wrapped == null)
{
throw new NotSupportedException("不支持的类型。");
}
WrappedQueryableProvider <T, M> provider = wrapped.Provider;
var visitor = new ExpressionWrapper <T, M>();
var expression = visitor.Visit(wrapped.Expression);
return(provider.InnerQueryProvider.CreateQuery <M>(expression));
}
private static Expression <Func <T, TResult> > UnwrapExpression <T, TResult>(Expression <Func <T, TResult> > expression, Type[] args)
{
ExpressionWrapper wrapper = new ExpressionWrapper(args[0], args[1]);
return((Expression <Func <T, TResult> >)wrapper.Visit(expression));
}
protected virtual Expression <Func <M, TResult> > WrapExpression <TResult>(Expression <Func <T, TResult> > expression)
{
ExpressionWrapper <T, M> wrapper = new ExpressionWrapper <T, M>();
return((Expression <Func <M, TResult> >)wrapper.Visit(expression));
}
