Creating a dictionary from another dictionary using LINQ

Question

I have a dictionary of the type:

IDictionary<foo, IEnumerable<bar>> my_dictionary 

bar class looks like this:

class bar {     public bool IsValid {get; set;}  } 

How can I create another dictionary with only those items that have IsValid = true.

I tried this:

my_dictionary.ToDictionary( p=> p.Key,                             p=> p.Value.Where (x => x.IsValid)); 

The problem with above code is that this creates a key with empty enumerable, if all the elements for that key were IsValid = false.

for example:

my_dictionar[foo1] = new List<bar> { new bar {IsValid = false}, new bar {IsValid = false}, new bar {IsValid = false}}; my_dictionary[foo2] = new List<bar> {new bar {IsValid = true} , new bar{IsValid = false}; var new_dict = my_dictionary.ToDictionary( p=> p.Key,                             p=> p.Value.Where (x => x.IsValid)); // Expected new_dict should contain only foo2 with a list of 1 bar item. // actual is a new_dict with foo1 with 0 items, and foo2 with 1 item. 

How do I get my expected.

Answer 1

Something like this?

my_dictionary     .Where(p=> p.Value.Any(x => x.IsValid))     .ToDictionary( p=> p.Key,                    p=> p.Value.Where (x => x.IsValid)); 

That will only include items where at least one of the values IsValid.