I need to return a list within a list using linq(lambda), however, still not getting required syntax.
I have a list of WikiMeta which I want to query and return all the WikiGroups as a new list.
Note: Some properties have been removed from clarity.
List<WikiMeta> Meta;
public class WikiMeta
{
public List<WikiGroup> Groups = new List<WikiGroup>();
}
public class WikiGroup
{
public string Name { get; set; }
}
You can get them all as a flat list using SelectMany:
var groups = meta.SelectMany(m => m.Groups).ToList();
This will give you a List<WikiGroup>.
You can perform any query you wish on the main List<WikiMeta> as such:
var filteredGroups = meta
.Where(m => m.IsActive) // Fictional "IsActive" boolean property.
.SelectMany(m => m.Groups)
.ToList();
Using this fluent-style functional approach to querying collections, you can start to build up more complicated queries.
If you wish to leave the query deferred until it is iterated, remove ToList, which will give you an IEnumerable<WikiGroup>.
List<T>? You can useWhereSelectMany, like:Meta.SelectMany(m => m.Groups);