Need a linq to objects query for a nested collection

Question

I am trying to select text from a collection that is three of four deep.

RootObject has a List<ResourceSet> resourceSets

The resourceSets has a List<Resources> resources

The resources has a List<RouteLeg> routeLegs

The routLegs has a List<ItineraryItem> itineraryItems

The each routeLeg contains and object called ItineraryItem and in that object there is a text property.

I am trying to pull out a list of all the text properties on the routeLeg object. As you can see it is nested pretty deep. I can obviously do this in nested loops..(as shown below) but want something cleaner using Linq to Objects but I am having trouble with the multiple nesting.

  ResourceSet testst = new ResourceSet();
            ResourceSet rs;          
            StringBuilder sb = new StringBuilder();

            for (int i = 0; i < _Result.resourceSets.Count; i++)
            {
                rs = _Result.resourceSets[i];


                for (int j = 0; j < rs.resources.Count; i++)
                {

                    Resource rec = rs.resources[j];

                    string test = rec.distanceUnit;

                    for (int k = 0; k < rec.routeLegs.Count; k++)
                    {
                        RouteLeg rl = rec.routeLegs[k];

                        for (int l = 0; l < rl.itineraryItems.Count; l++)
                        {
                            ItineraryItem ii = rl.itineraryItems[l];                           
                            sb.Append(ii.instruction.ToString());
                        }
                    }

                }
            }

Answer 1

You can use SelectMany to fetch the internal items:

var items = result.resourceSets
                  .SelectMany(rs => rs.resources)
                  .SelectMany(res => res.routeLegs)
                  .SelectMany(rl => rl.itineraryItems)
foreach(var x in items)
    sb.Append(x.instruction.ToString());