无法访问具有group by的字段和使用linq的多个连接

我想只列出那些平均值与记录不同的类别。

这种差异存在于2个表中： TestOperation，TestOperationDifference

我想计算以下3个字段的平均值：

TestOperation:DiffPerc If DiffPerc < 100 "Difference is there and take value of DiffPerc to calculate average" else "Dont take that record" TestOperationDifference:DiffPerc,DiffRec If DiffPerc < 100 "Difference is there and take value of DiffPerc and DiffRec to calculate average" else "Dont take that record" finalAverage=( Average(TestOperation.DiffPerc) + Average(TestOperationDifference.DiffPerc) + Average(TestOperationDifference.DiffRec) )/3 

输出如下：

 [0]=Mobile Electronics FinalAverage=30.00 [1]=Shoes Sports FinalAverage=70.00 . . . 

我的代码：

 public class Category { public int Id { get; set; } public string Name { get; set; } public Nullable ParentId { get; set; } public virtual ICollection Variants { get; set; } } public class Variants { public int Id { get; set; } public string Name { get; set; } public string Type { get; set; } public int CategoryId { get; set; } public virtual ICollection SubVariants { get; set; } public virtual Category Category { get; set; } } public class SubVariants { public int Id { get; set; } public int VariantId { get; set; } public string Name { get; set; } public virtual Variants Variants { get; set; } public virtual ICollection TestOperationDifference { get; set; } public virtual ICollection TestOperationDifference1 { get; set; } public virtual ICollection TestOperation { get; set; } public virtual ICollection TestOperation1 { get; set; } } public class Test { public int Id { get; set; } public string Version { get; set; } public virtual ICollection TestOperation { get; set; } public virtual ICollection TestOperationDifference { get; set; } } public class TestOperation { public int Id { get; set; } public Nullable TestId { get; set; } public int SourceSubVariantId { get; set; } public int TargetSubVariantId { get; set; } public decimal DiffPerc { get; set; } public virtual SubVariants SubVariants { get; set; } public virtual SubVariants SubVariants1 { get; set; } public virtual Test Test { get; set; } } public class TestOperationDifference { public int Id { get; set; } public Nullable TestId { get; set; } public int SourceSubVariantId { get; set; } public int TargetSubVariantId { get; set; } public decimal DiffPerc { get; set; } public decimal DiffRec { get; set; } public virtual SubVariants SubVariants { get; set; } public virtual SubVariants SubVariants1 { get; set; } public virtual Test Test { get; set; } } 

我的查询：

  var query = from cat in context.Category join v in context.Variants on cat.Id equals v.CategoryId join sv in context.SubVariants on v.Id equals sv.VariantId join to in context.TestOperation on sv.Id equals to.SourceSubVariantId join tod in context.TestOperationDifference on sv.Id equals tod.SourceSubVariantId where (to.DiffPerc < 100) || (tod.DiffPerc < 100 ) group cat by new {catid = cat.Id} into grp select new { subcategoryname=grp. //not getting property here ParentCategoryName=grp. FinalAverage= } 

但是在上面的查询中，当我尝试访问子类别名称时，我无法访问它。

演示小提琴

Answer 1

基本查询应如下所示

  var query = (from cat in category join v in variants on cat.Id equals v.CategoryId join sv in subVariants on v.Id equals sv.VariantId into grp select new { id = cat.Id, subvariant = v.SubVariants, name = cat.Name, type = v.Type}) .GroupBy(x => new {id = x.id, subvariant = x.subvariant}); 

您需要将testOperations和testOperationDifferences应用于查询。

Answer 2

那是因为grp是集合的IGrouping的实例。 正如您可能已经猜到的那样，您需要访问集合的某些元素以获取Category的Name属性，或者您可以通过Name和Id对您的Category集合进行分组（如果在您的情况下有意义），那么您可以访问它使用grp.Key.Name