Filtering nested list is not bringing back the correct result set

Question

I currently have a list of skills which looks something like:

var list = new List<Test>
    {
        new Test
        {
            Name = "Some Name",
            Skills = new List<Skill>
            {
                new Skill { SkillName = "Java" },
                new Skill { SkillName = "JavaScript" },
                new Skill { SkillName = "C#" },
                new Skill { SkillName = "CSS" }
            }
        }
    };

Now, I am trying to filter the result by the search term Java for which the code looks something like:

var searchTerm = "Java";
    
var filteredList = list.Where(t => t.Skills.Any(s => s.SkillName.Contains(searchTerm))).ToList();

Here, I would expect the filteredList to contain Java & JavaScript but it's bringing back all the 4 items. Does anyone know where I'm going wrong?

dotnetfiddle

Answer 1

You need to create a new list to achieve this. You could do this as follows:

var filteredList =
    // where filters down the list to the tests you are interested in(ones containing a skill that has the search term)
    list.Where(t => t.Skills.Any(s => s.SkillName.Contains(searchTerm)))
        // select creates a new list, where each test only has the skills that match the search term
        .Select(t => new Test
                     {
                       Name = t.Name,
                       Skills = t.Skills.Where(s => s.SkillName.Contains(searchTerm)).ToList()
                     })
        .ToList();