Question

I have the following situation:
An “Conversations” entity/table which has multiple Tags associated to it.
Tag is also an entity/table – the key/id is tagName (a string).

On the client side (javascript) I work with arrays of string when dealing with Tags.

Now I want want to retrieve all the conversations that have all given tags.

---

The input is an array of strings and the output should be a collection of Conversations

I’ve tried:

var filterTags = new List<EFModels.Tag>();
foreach (var tagName in tags)
            {
               filterTags.Add(new EFModels.Tag() { Name = tagName});
            }

var conversations = from c in context.Conversations where !c.Tags.Except(filterTags).Any() select c ;

The problem with this is: Unable to create a constant value of type 'EFModels.Tag'. Only primitive types or enumeration types are supported in this context – which makes sense.

Now how can I do my select? What’s the best approach? (I still want to use linq and not write the sql select)

Answer 1

You can project c.Tags to tag name.

I guess it will look like that

var conversations = from c in context.Conversations where !c.Tags.Select(tag => tag.Name ).Except(filterTags).Any() select c ;

Where filterTags is the list of strings containing the names of the tags