How to do ForEach only on objects in hashtable that match object in array

Question

I have a hashtable used in a job, each hash.key is a job name:

$myhashtable = @{ 
    'somelocation'    = 'somevalue'
    'otherlocation'   = 'othervalue'
}

I run the hashtable against a function, the function is a Start-Job that runs for each object in the hashtable.

foreach ( $location in $myhashtable.GetEnumerator() )
{
    SomeFunction
}

I then get the names of stopped jobs:

$joblist = Get-Job | Where-Object { $_.State -eq "Stopped" }
$joblist = $joblist.name

Trying to do the same as above against the function but only for the jobs that have stopped:

foreach( $location in $myhashtable.GetEnumerator() )
{
    if $location.key matches an object in $joblist}( 
    do SomeFunction for those $location.keys)
}

I've tried various foreach if and where but can't hit on it.

Thanks!

Have you tried using an if statement at the top that just sees if item is in job list, and if not, just `continue;`? — Josh Heaps, Jul 01 '22 at 19:08
So what do you want to match of `$Array`, the key or the value? I. e. is the job name the array key or the array value? (Nitpicking: it isn't actually an array, but a `Hashtable`) — zett42, Jul 01 '22 at 19:21
_"I've tried various foreach if and where"_, but you don't show any of these attempts. — Theo, Jul 01 '22 at 19:33
Your question, as it stand, is not clear. If you want to get your array that was created from a job, you need to use `receive-job` first. If you want to compare arrays and / or object, you can use `Compare-Object`. — Sage Pourpre, Jul 01 '22 at 19:37
On a separate note, duplicate keys are not allowed in hash literals, i.e., your `$Array`. — Abraham Zinala, Jul 01 '22 at 20:05

score 1 · Answer 1 · edited Jul 02 '22 at 14:35

1

as @zett42 noted, your question uses which you name $Array. Renaming this in my reply to avoid confusion, but I think the code below will do what you are trying to do.

PS> $myHashtable = @{
>> 'key1'   = 'value1'
>> 'key2'   = 'value2'
>> 'key3'   = 'value3'
>> }
PS> $joblist= 'key1', 'key2'
PS> $myHashtable.keys | ForEach-Object { if( $_ -in $joblist ){ $myHashtable[$_] } }
value1
value3

edited Jul 02 '22 at 14:35

Steven

6,817
1
14
14

answered Jul 01 '22 at 19:48

ben

51
3

3

If you're interested in switching it up a bit, you can use the `.Where({})` operator instead: `$myHashtable.GetEnumerator().Where{$_.key -in $joblist}.Value`, or `.Key` for the key name. – Abraham Zinala Jul 01 '22 at 20:21
1

@Retrotube I'm having a bit of trouble parsing just what output you are looking for. Could you please update your question to include what the intended output would look like? – ben Jul 01 '22 at 20:49
1

@ben May I suggest you add a pseudo function call to your final `If ` block. Reading the question I think that might be the final piece. – Steven Jul 02 '22 at 14:42
@steven I'm not sure quite what that means or what problem it would solve. If you'd care to put the code in a comment or point me at an example elsewhere, I'd be glad to learn more. – ben Jul 17 '22 at 19:43
@ben Sorry you read too much into that. From the original question I think the op wants to call a function on those values. When I say put a pseudo function call, it's just a place holder to represent that. – Steven Jul 18 '22 at 18:11

zett42 · Answer 2 · 2022-07-02T22:18:34.783

Here is a possible solution:

$myhashtable = @{ 
'somelocation'    = 'somevalue'
'otherlocation'   = 'othervalue'
}

# For each job that has stopped and whose name matches a key in $myhashtable
Get-Job | Where-Object { $_.State -eq Stopped -and $myhashtable.Contains( $_.Name ) } | 
    ForEach-Object {
        SomeFunction 
    }

When you have a hashtable, you normally shouldn't loop over it, to search for a key somewhere else, which is very inefficient. Instead do it the other way around, loop over the array of objects you want to match and do a lookup in the hashtable, e.g. by calling the .Contains method or using the index operator []. The .Contains method returns $true if the given argument matches one of the keys of the hashtable. This is a very efficient operation, because a hashtable is optimized for fast lookup of keys.

How to do ForEach only on objects in hashtable that match object in array

2 Answers2