Linq where sublist contains a partial value

Question

I want to search for items where the search term exists within one of its sub items

For example I have a device with settings, I want a list of all devices which have a DeviceSetting with Id=1 and value.Contains("test"). I am using LINQ to SQL so if anything can be done to keep this fast (and avoid projection to POCO) that would be great

How do I achieve this?

Device
{
   List<DeviceSetting> Settings { get; set; }
}

DeviceSetting
{
    int Id;
    string value;
}

var devices = new List<Device>(); // populated from EF

var search = "test";
var results = devices.Where(d => d.Settings.Contains(searchTerm));

Answer 1

Use Enumerable.Any to check if any of device settings matches some condition:

var results = 
    devices.Where(d => d.Settings.Any(s => s.value.Contains(searchTerm)));

If you also need to check for Id, then add this condition to predicate of Any:

d.Settings.Any(s => s.Id == 1 && s.value.Contains(searchTerm))

NOTE: You can do this filtering on server side if you will not save devices into list.