I have a list of projects with a list of project members for each project as follows

public List<Project> Projects { get; set; }
    public class Project
    {
        public Guid Id { get; set; }
        public string  Title { get; set; } 
        public string Description { get; set; }
        public List<Member> Members { get; set; }
    }
    
    public class Member{
        public Guid Id { get; set; }
        public string Name { get; set; }
        public string Address { get; set; }
    }

I want to select projects for a list of member Ids using LINQ, thank you!

CodePudding user response：

I want to select projects for a list of member Ids using LINQ

List<Guid> memberIdlist = ... // fill

You can use Intersect...Any

IEnumerable<Project> projectsOfMembers = Projects
    .Where(p => p.Members.Select(m => m.Id).Intersect(memberIdlist).Any());

This is an efficient approach if this list can get large, since Intersect is a set based appoach and Any stops at the first true. If it's small you could also use:

IEnumerable<Project> projectsOfMembers = Projects
    .Where(p => p.Members.Any(m => memberIdlist.Contains(m.Id)));

I suggest to not use a List<Guid> but a HashSet<Guid>. Then you can use Overlaps:

IEnumerable<Project> projectsOfMembers = Projects
    .Where(p => memberIdSet.Overlaps(p.Members.Select(m => m.Id)));

CodePudding user response：

If you have a list of Guids, you can check against it by using .Contains() inside .Where():

var projects = new List<Project>();
//Add projects

var memberIds = new List<Guid>();
//Add member IDs

var memberProjects = projects
    .Where(p => p.Members.Any(m => memberIds.Contains(m.Id)));

CodePudding user response：

try something like this:

        var projects = new List<Project>();
        List<Guid>searched_value = new List<Guid>();
        var newList = projects.Where(p => p.Members.Any(m => searched_value.Any(s => s == m.Id))).ToList();

Edited to reflect the OP wants to check against a List