Powershell hash table storing values of "System.Collections.DictionaryEntry"

Bobazonski picture Bobazonski · Mar 18, 2016 · Viewed 14.8k times · Source

When I execute the command:

$var = @{a=1;b=2}

in Powershell (Version 3), $var ends up with a value of {System.Collections.DictionaryEntry, System.Collections.DictionaryEntry}. Why is this happening? How can I store the values I want to store?

Answer

Frode F. picture Frode F. · Mar 18, 2016

That's because your ISE is enumerating the collection to create the variable-treeview, and the objects returned from a HashtableEnumerator which you get from $var.GetEnumerator() are DictionaryEntry-objects.

$var = @{a=1;b=2}

#Collection is a Hashtable
$var | Get-Member -MemberType Properties    

   TypeName: System.Collections.Hashtable

Name           MemberType Definition
----           ---------- ----------
Count          Property   int Count {get;}
IsFixedSize    Property   bool IsFixedSize {get;}
IsReadOnly     Property   bool IsReadOnly {get;}
IsSynchronized Property   bool IsSynchronized {get;}
Keys           Property   System.Collections.ICollection Keys {get;}  
SyncRoot       Property   System.Object SyncRoot {get;}               
Values         Property   System.Collections.ICollection Values {get;}

#Enumerated objects (is that a word?) are DictionaryEntry(-ies)
$var.GetEnumerator() | Get-Member -MemberType Properties

   TypeName: System.Collections.DictionaryEntry

Name  MemberType    Definition
----  ----------    ----------
Name  AliasProperty Name = Key
Key   Property      System.Object Key {get;set;}  
Value Property      System.Object Value {get;set;}

Your value (1 and 2) is stored in the Value-property in the objects while they Key is the ID you used (a and b).

You only need to care about this when you need to enumerate the hashtable, ex. When you're looping through every item. For normal use this is behind-the-scenes-magic so you can use $var["a"].