Powershell - combine switch statement and loop

Question

I have a piece of code presented below, it takes values from a json file. This is a array of string --> $Json.Names. I would like to avoid duplicate lines like --> $Json.Names[0].Name {$Json.Names[0].Name; break}. Second case is that Array $Json.Names could have different length, array can have 6 and more or less elements. I want to make this switch statement more elastic. I tried to use for loop and while loop, but in this case these loops doesn't help me. Is there any clever method to make this code more sophisticated/elastic and avoid duplicate mentioned code lines$Json.Names[0].Name {$Json.Names[0].Name; break}

$Json = Get-Content "$path" | out-string | ConvertFrom-Json
$Name = switch ($Member) {
    $Json.Names[0].Name  {$Json.Names[0].Name; break}
    $Json.Names[1].Name  {$Json.Names[1].Name; break}
    $Json.Names[2].Name  {$Json.Names[2].Name; break}
    $Json.Names[3].Name  {$Json.Names[3].Name; break}
    $Json.Names[4].Name  {$Json.Names[4].Name; break}
    $Json.Names[5].Name  {$Json.Names[5].Name; break}
    $Json.Names[6].Name  {$Json.Names[6].Name; break}
    default {"Unknown Name"}
}

What does the json look like? Switch is a loop: switch (1..5) { $_ { $_ } } — js2010
– js2010, Commented Nov 6, 2019 at 13:08

js2010 · Accepted Answer · 2019-11-06 16:04:44Z

2

Assuming this structure:

$json = [pscustomobject]@{names = [pscustomobject]@{name ='joe'},
  [pscustomobject]@{name ='john'},
  [pscustomobject]@{name ='james'}}

Assuming $member is a single name, you can say

$name = $json.names.name -eq $member # an array of one

$name would be a null array if there's no match.

if (! $name) { $name = 'Unknown Name' }

Or, in the language of Powershell 7 preview 5:

$name ??= 'Unknown Name'

You also may want to make a hashtable of the names.

edited Nov 6, 2019 at 16:04

answered Nov 6, 2019 at 15:18

js2010

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Comments

Mathias R. Jessen · Accepted Answer · 2019-11-06 12:06:20Z

1

You can take advantage of property enumeration and simplify your code pretty significantly:

# define our default
$Name = "Unknown Name"

# define the list of names 
$Json = Get-Content "$path" | ConvertFrom-Json
$Names = $Json.Names.Name

# update $Name if applicable
if($Names -contains $member){
    $Name = $member
}

answered Nov 6, 2019 at 12:06

Mathias R. Jessen

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1 Comment

tester81 Over a year ago

Thx, it helps me, tested pipeline, and it works, similar solution to this proposed by @js2010

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