IEnumerable中的地方ID <int> 在单个LINQ查询中

Question

I've got a dataset of this format:

ID   Make        Model
==   =========   =========
1    Ford        Fusion
2    Ford        Fusion
3    Chevy       Malibu

I want the result to be:

Make      Model      IDs
========  =========  ===
Ford      Fusion     IEnumerable<int> {1,2}
Chevy     Malibu     IEnumerable<int> {3}

I'm implementing multi-line edits in a grid so I need to save the IDs of each line while displaying the distinct properties to edit. Once the editing is done then I will have the IDs to update.

I'm wondering if there is a way to collate these IDs with a single LINQ query. Currently I've been successful but with two queries.

Answer 1

A simple group by should work:

var query=from c in cars
          group c.Id by new {c.Make,c.Model} into g
          select new {g.Key.Make, g.Key.Model, Ids=g.ToList() };

Answer 2

You can try something like this:

var results = context.Cars
                     .GroupBy(c => new { c.Make, c.Model })
                     .Select(g => new
                     {
                         Make = g.Key.Make,
                         Model = g.Key.Model,
                         IDs = g.Select(c => c.ID)
                     });