我有一个名为RouteExport的复杂对象列表,我试图根据CustomerNumber值进行展平和分组,以便返回一个看起来像的匿名对象
{ CustomerNumber = "1235",Route = route1,Section = section2,Sequence = sequence2 }
要么
{ CustomerNumber = "1234",Section = null,Sequence = null }
模型看起来像这样:
public class RouteExport { public string Name { get; set; } public string Term { get; set; } public List<string> CustomerNumbers { get; set; } public List<SectionExport> Sections { get; set; } } public class SectionExport { public string Name { get; set; } public List<string> CustomerNumbers { get; set; } public List<SequenceExport> Sequences { get; set; } } public class SequenceExport { public string Name { get; set; } public List<string> CustomerNumbers { get; set; } }
每个对象都有一个CustomerNumber列表,如果它们在该路由/部分/序列中,则该列表包含客户的编号.我想根据该客户编号对每个对象进行分组.到目前为止,我一直在使用这个:
var flattendExport = exportviewmodel.ExportContainer.Routes .SelectMany(rt => rt.Sections .SelectMany(sec => sec.Sequences .SelectMany(seq => seq.CustomerNumbers .Select(custNum => new { rt,sec,seq,custNum })))).ToList();
它会使对象变平,但不会按CustomerNumber分组,也不会为节或序列返回null.
如何创建一个返回按每个对象的CustomerNumbers分组的展平列表的查询,如果它们不在某个部分或序列中,则返回null?
更新测试用例
我没有充分说出原始问题所以做了一些编辑.我想分组客户的号码,以便这个数据:
var data = new List<RouteExport> { new RouteExport { CustomerNumbers = new List<string> { "1","2" },Sections = new List<SectionExport> { new SectionExport() { CustomerNumbers = new List<string> { "1" },Sequences = new List<SequenceExport> { new SequenceExport() { CustomerNumbers = new List<string> { "1" } } } } } } };
返回以下结果:
{ CustomerNumber = "1",Section = section1,Sequence = sequence1},{ CustomerNumber = "2",Sequence = null}
解决方法
您可以使用LINQ的DefaultIfEmpty插入Sections集合为空时所需的空值.见
https://msdn.microsoft.com/en-us/library/bb355419(v=vs.110).aspx
在第二个结束时.SelectMany(…)添加:
.DefaultIfEmpty(new { rt,null,cystNum })
对于没有部分的每条路线,它都会创建一个虚拟结果.
编辑:鉴于您更改的要求,它将如下所示:
var res = data.SelectMany(r => r.CustomerNumbers .SelectMany(c => r.Sections.Where(s => s.CustomerNumbers.Contains(c)) .SelectMany(s => s.Sequences .Select(seq => new { CustomerNumber = c,Route = r,Section = s,Sequence = seq })) .DefaultIfEmpty(new { CustomerNumber = c,Section = (SectionExport)null,Sequence = (SequenceExport)null }))) .ToList();