Linq to Entity，随机顺序 [英] Linq to Entities, random order

问题描述

如何以随机顺序返回匹配的实体?
只是要清楚这是实体框架的东西和 LINQ to Entities.

How do i return matching entities in a random order?
Just to be clear this is Entity Framework stuff and LINQ to Entities.

(航空代码)

IEnumerable<MyEntity> results = from en in context.MyEntity
                                where en.type == myTypeVar
                                orderby ?????
                                select en;

谢谢

我尝试将其添加到上下文中:

I tried adding this to the context:

public Guid Random()
{
    return new Guid();
}

并使用此查询:

IEnumerable<MyEntity> results = from en in context.MyEntity
                                where en.type == myTypeVar
                                orderby context.Random()
                                select en;

但是我遇到了这个错误:

But i got this error:

System.NotSupportedException: LINQ to Entities does not recognize the method 'System.Guid Random()' method, and this method cannot be translated into a store expression..

编辑(当前代码):

IEnumerable<MyEntity> results = (from en in context.MyEntity
                                 where en.type == myTypeVar
                                 orderby context.Random()
                                 select en).AsEnumerable();

推荐答案

简单的解决方案是创建一个数组(或一个 List)，然后随机化其索引.

The simple solution would be creating an array (or a List<T>) and than randomize its indexes.

static IEnumerable<T> Randomize<T>(this IEnumerable<T> source) {
  var array = source.ToArray();
  // randomize indexes (several approaches are possible)
  return array;
}

就个人而言，我发现 Jon Skeet 的回答更优雅:

Personally, I find the answer of Jon Skeet is more elegant:

var results = from ... in ... where ... orderby Guid.NewGuid() select ...

当然，您可以使用随机数生成器代替 Guid.NewGuid().

And sure, you can take a random number generator instead of Guid.NewGuid().

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