Finding objects which contains at least all elements from subset using RavenDB and LINQ

Question

I have simple type `Question`: ``` public class Question { public Question(string id) { Id = id; Tags = new List(); } public string Id { get; private set; } public IList Tags { get; set; } } ``` I have defined sample collection of such questions: ``` var q1 = new Question("q1") { Tags = new List() {"aa", "bb"} }; var q2 = new Question("q2") { Tags = new List() {"aa"} }; var q3 = new Question("q3") { Tags = new List() {"aa", "bb", "cc"} }; var q4 = new Question("q4"); var questions = new List() {q1, q2, q3, q4}; ``` Now I need to find all questions, which contains at least all tags, from given subset. Subset is defined below: ``` string[] tags = new[] {"aa", "bb"}; ``` The query which I use to get desired result is: ``` var result = questions.Where(x => !tags.Except(x.Tags).Any()).ToList(); ``` Result is a list of 2 questions: q1 and q3, which works properly while I'm using linq-to-objects. Unfortunately, while I'm trying to query such…

Accepted Answer

Jarek, what you want to do is:

```
var q = session.Query<Question>();
foreach(var tag in tags)
{
    var currentTag = tag;
    q = q.Where(x=>x.Tags.Any(xTag=>xTag == currentTag));
}
```

This will give you all the questions that have at least all those tags.

Finding objects which contains at least all elements from subset using RavenDB and LINQ

Solution

Problem