How to Call Keys in Nested Hash Tables?

Question

I'm studying Hash Tables in PowerShell at the moment and I learned that variables can be used as both keys and values. I had already created a hash table by this point and wanted to see how I could nest that within another hash table. So, here's the information for what I'm doing:

I created a hash table named $avatar. Within this are the keys "Episode 1", "Episode 2", "Episode 3", etc. along with the name of each episode as the value.

$avatar = [ordered]@{
      "Episode 1" = "The Boy in the Iceberg";
      "Episode 2" = "The Avatar Returns";
      "Episode 3" = "The Southern Air Temple";
}

So then I wanted to put this hash table within another with the name $shows.

$shows = [ordered]@{
      "Avatar" = $avatar;
}

So, here's my question. Did I write the syntax for nesting the hash table correctly? If not, how should it be written? Also, what is the syntax required for calling a specific key from the nested hash table?

user_4085331 · Answer

It's fun and can teach you a lot just to investigate each little part.

So we know we have the first hash table, it's made up of "keys" and "values"

$avatar.keys

Episode 1
Episode 2
Episode 3

$avatar.values

The Boy in the Iceberg
The Avatar Returns
The Southern Air Temple

If you want to loop over each name/value pair, use .GetEnumerator()

$avatar.GetEnumerator() | ForEach-Object {
    "Name: $($_.name)"
    "Value: $($_.value)"
}

Name: Episode 1
Value: The Boy in the Iceberg
Name: Episode 2
Value: The Avatar Returns
Name: Episode 3
Value: The Southern Air Temple

You can take each key and loop over them to act on one at a time

$shows.Keys | ForEach-Object {
    $shows.$_
}

Name                           Value                                                                                                                                                          
----                           -----                                                                                                                                                          
Episode 1                      The Boy in the Iceberg                                                                                                                                         
Episode 2                      The Avatar Returns                                                                                                                                             
Episode 3                      The Southern Air Temple

When you get into nesting, just know you will have to peel back each layer.

$shows.Keys | ForEach-Object {
    $shows.$_.GetEnumerator()
}

Name                           Value                                                                                                                                                          
----                           -----                                                                                                                                                          
Episode 1                      The Boy in the Iceberg                                                                                                                                         
Episode 2                      The Avatar Returns                                                                                                                                             
Episode 3                      The Southern Air Temple

or

$shows.Keys | ForEach-Object {
    foreach($key in $shows.$_.keys){
        $shows.$_.$key
    }
}

The Boy in the Iceberg
The Avatar Returns
The Southern Air Temple

Or lots of different ways

How to Call Keys in Nested Hash Tables?

1 Answers