Question

I’m trying to convert a List<Topic> to an anonymous or dynamic type via linq projection… I’m am using the following code, but it doesn’t seem to work properly. It returns the dynamic type without error, however, if I try to enumerate the children field (list<object/topic>) then it says

Results View = The type '<>f__AnonymousType6<id,title,children>' exists in both ‘MyWebCore.dll’ and ‘MvcExtensions.dll’

Strange.

Here is the code I am using:

protected dynamic FlattenTopics()
{
    Func<List<Topic>, object> _Flatten = null; // satisfy recursion re-use
    _Flatten = (topList) =>
    {
        if (topList == null) return null;

        var projection = from tops in topList
                         select new
                         {
                             id = tops.Id,
                             title = tops.Name,
                             children = _Flatten(childs.Children.ToList<Topic>())
                         };
        dynamic transformed = projection;
        return transformed;
    };

    var topics = from tops in Repository.Query<Topic>().ToList()
                 select new
                 {
                     id = tops.Id,
                     title = tops.Name,
                     children = _Flatten(tops.Children.ToList<Topic>())
                 };

    return topics;
}

All i’m doing is flattening a list of self containing objects – basically it’s a list of POCOs that will be stuffed into a tree view (jstree).

The Topic class is defined as:

public class Topic
{
    public Guid Id {get;set;}
    public string Name {get;set;}
    public List<Topic> Children {get;set;}
}

And here is an example of what the first member of the returned dynamic object looks like:

[0] = { 
    id = {566697be-b336-42bc-9549-9feb0022f348},
    title = "AUTO", 
    children = {System.Linq.Enumerable.SelectManyIterator
          <MyWeb.Models.Topic,
           MyWeb.Models.Topic,
           <>f__AnonymousType6<System.Guid,string,object>
          >} 
 }

Answer 1

Here is the proper way – have to load into the a DTO / POCO and return that:

_Flatten = (topList) =>
        {
            if (topList == null) return null;

            var projection = from tops in topList
                             //from childs in tops.Children
                             select new JsTreeJsonNode
                             {
                                 //id = tops.Id.ToString(),
                                 data = tops.Name,
                                 attr = setAttributes(tops.Id.ToString(), tops.URI),
                                 state = "closed",
                                 children = _Flatten(tops.Children)
                             };


            return projection.ToList();
        };