LINQ按子值排序

Question

I have an EF model that looks like:

public class MetaData
{
    public ICollection<MetaDataDictionary> MetaDataDictionary { get; set; }
}

public partial class MetaDataDictionary
{
    public string Key { get; set; }
    public string Value { get; set; }
}

public List<MetaData> MetaDataList { get; set; }

...so I could have an instance like:

MetaDataList 
  MetaData1
    MetaDataDictionary          
      { key = "aaa", value = "4" }
      { key = "bbb", value = "5" }     
      { key = "ccc", value = "6" }     
  MetaData2
    MetaDataDictionary 
      { key = "aaa", value = "1" }
      { key = "bbb", value = "2" }     
      { key = "ccc", value = "3" }              

The goal is to sort MetaDataList based on a value of a specific key (for example key "aaa") of the MetaDataDictionary, output should be:

MetaDataList 
  MetaData1
    MetaDataDictionary          
      { key = "aaa", value = "1" }
      { key = "bbb", value = "2" }     
      { key = "ccc", value = "3" }     
  MetaData2
    MetaDataDictionary 
      { key = "aaa", value = "4" }
      { key = "bbb", value = "5" }     
      { key = "ccc", value = "6" }   

As you see, it is now sorted on values of key "bbb".

I tried:

var sorted = metaDataList.OrderBy(md => md.MetaDataDictionary.Select(mdd => mdd.Key == "aaa").Single()).ToList();

...but it complains about 'DbSortClause expressions must have a type that is order comparable'.

Any pointers how I can make this work?

Thanks!

EDIT: just tried this:

var sorted = metaDataList.OrderBy(md => md.MetaDataDictionary.Where(mdd => mdd.Key == "aaa").Select(mdd => mdd.Value).FirstOrDefault()).ToList();

Seems to work, but if someone has a better solution, feel free to share :)

Answer 1

Maybe this?

metaDataList.OrderBy(md => md.MetaDataDictionary.First(mdd => mdd.Key == "aaa").Value)
            .ToList();

I haven't tested it yet but believe it should work.