在匿名类型声明中按属性索引排序 [英] Ordering by Index of property in Anonymous Type Declaration

问题描述

我有一个复杂的问题，没有涉及太多细节.我只是想知道这是否可能.

I have a complex problem, without going into too many details. I'm just wondering if this is possible.

我有一个Ordered Linq查询，该查询获取数据的子集并将其推入DataTable.

I have an Ordered Linq query which gets a subset of data and pushes it into a DataTable.

var FormattedDataSet = DataSet.Select(t => new
{
    ItemNumber = t.ExtTitleID,
    Name = "<a href='/Title/Preview/" + t.ID + "'>" + t.TitleFullName + "</a>",
    Master_Edited = t.MediaDetails.FirstOrDefault().Datecaptured
}).ToList();

Int是否可以根据匿名类型的声明的索引对此进行排序?

Is it Possible Int to sort this based on the index of the declaration of the Anonymous Type?

0 => ItemNumber
1 => Name
2 => MasterEdited

我需要能够做到这一点，而无需显式声明要进行排序的列名，因此，它对于任何匿名类型都可以通用.

I need to be able to do this with out explicitly declaring the column name to sort by, so this can work generically for any anonymous type.

推荐答案

我希望这还不算太晚，但是我为您准备了一些工作代码.我以前在项目中使用过它，并且没有引起任何明显的问题.

I hope this is not too late but I have some working code for you. I've used this in a project before and it hasn't caused any noticed problems.

public static IOrderedQueryable<T> OrderByPropertyDeclarionIndex<T>(this IQueryable<T> source, int propertyIndex, bool isDescending = false)
{
    string OrderByText = isDescending ? "OrderByDescending" : "OrderBy";
    return ApplyOrder(source, propertyIndex, OrderByText);
}


private static IOrderedQueryable<T> ApplyOrder<T>(IQueryable<T> source, int property, string methodName)
{

    var type = typeof(T);
    var arg = Expression.Parameter(type, "x");
    Expression expr = arg;

    var propertyinfos = type.GetProperties();


    var pi = propertyinfos[property];



    expr = Expression.Property(expr, pi);
    type = pi.PropertyType;

    var delegateType = typeof(Func<,>).MakeGenericType(typeof(T), type);
    var lambda = Expression.Lambda(delegateType, expr, arg);

    var result = typeof(Queryable).GetMethods().Single(
            method => method.Name == methodName
                    && method.IsGenericMethodDefinition
                    && method.GetGenericArguments().Length == 2
                    && method.GetParameters().Length == 2)
            .MakeGenericMethod(typeof(T), type)
            .Invoke(null, new object[] { source, lambda });
    return (IOrderedQueryable<T>)result;
}

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