在选择查询中扩展现有(匿名)类型 [英] Extend an existing (anonymous) type in a select query

问题描述

在使用LinqPad时，我有一个Select x, Extra=f(y)查询，我想在其中返回x的所有属性(和字段)，并返回与Extra相同的级别，而不是分别作为x和Extra属性(或字段).

While working with LinqPad I have a Select x, Extra=f(y) query where I'd like to return all the properties (and fields) of x at the same level as Extra, rather than as separate x and Extra properties (or fields).

可以做到吗?

即我想要Select x.p1, x.p2, Extra=f(y)而不用输入太多.

I.e. I want Select x.p1, x.p2, Extra=f(y) without having to type that much.

请注意，x的类型实际上可能是匿名的，也可能不是匿名的，只是有点不透明或太大而无法手动复制.由VB.NET隐式键入和C#显式new {}产生的类型是匿名的.

Note the type of x may or may not actually be anonymous, just somewhat opaque or just too big to copy out manually. The type resulting from the VB.NET implicit typing and the C# explicit new {} is anonymous.

推荐答案

Jon Skeet已经在此处否定回答了这个问题. (但这个问题不是重复的，因为这是特例).

Jon Skeet has already answered this question negatively here (but that question is not a duplicate because it's a special case).

作为解决方法，这里的My Extensions至少列出了准备粘贴回Select查询中的属性和字段.

As a workaround here are My Extensions to at least list the properties and fields ready to be pasted back into the Select query.

// Properties so you can "extend" anonymous types
public static string AllProperties<T>(this T obj, string VarName)
{
    var ps=typeof(T).GetProperties();
    return ps.Any()?(VarName + "." + string.Join(", " + VarName + ".", from p in ps select p.Name)):"";
}

// Fields so you can "extend" anonymous types
public static string AllFields<T>(this T obj, string VarName)
{
    var fs=typeof(T).GetFields();
    return fs.Any()?(VarName + "." + string.Join(", " + VarName + ".", from f in fs select f.Name)):"";
}

您可能很幸运，只能够说出Select x.AllProperties("x") Take 1，但是当您需要避免Linq-to-SQL成为障碍时，您需要添加更多内容:(from ... Select x).First().AllProperties("x")，如果需要，还可以添加更多的选项获取属性和字段(就像我发现的那样，使用LinqPad生成的实体).

You may be lucky enough to just be able to say Select x.AllProperties("x") Take 1 but when you need to avoid Linq-to-SQL getting in the way you need to add more: (from ... Select x).First().AllProperties("x"), with even more hoops if you need to get both properties and fields (as I found you do with the entities generated by LinqPad).

这些将产生像"x.p1, x.p2"这样的字符串，可以将其粘贴回原始的Select查询中.

These will produce a string like "x.p1, x.p2" that can be pasted back into the original Select query.

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