EF Intersect Syntax

Question

A UI allows users to select one or many tags. I would like to select all Nodes that have ALL that tags the user entered associated, not just a single tag.

public JsonResult SearchNodesByTags(string[] tags)
{
    var dbTags = _DbContext.Tags.Where(t => tags.Contains(t.DisplayName)).ToList();
    var nodes = _DbContext.Nodes.Where(n => n.Tags.Intersect(dbTags).Any());  
    // Error about intersection with non primitive

    return Json(nodes);
}

Answer 1

You can do this in one statement:

var nodes = _DbContext.Nodes
            .Where(n => n.Tags.All(t => tags.Contains(t.DisplayName)));

Your statement is not correct because dbTags is a local list containing Tag objects. When you use this list in a LINQ-to-Entities expression there is no way to translate these objects into SQL variables. That's only possible with primitive values.