How to get index of hashtable in array? - arrays

Question

I'm having a little trouble finding the index of a hashtable in an array. I create a JSON with this code:
$start = {
Clear-Host
$BIB = Read-Host 'Bibliothek'
$BIBName = Read-Host 'Bibliothek Name'
$Standort = Read-Host 'Bibliothek Standort'
$Autor = Read-Host 'Buchautor'
$BuchName = Read-Host 'Buchname'
$jsonfile = "C:\Skripte\bibV2-1000.xml"
if(![System.IO.File]::Exists($jsonfile)){
$Data = #{BIBs = #(
#{$BIB = #{BIBName=$BIBName},
#{Standort = $Standort},
#{Bücher = #(
#{BuchName = $BuchName;
Autor = $Autor})
}}
)}
ConvertTo-Json -Depth 50 -InputObject $Data | Add-Content $jsonfile
.$continue
} else {
$jsonfile = "C:\Skripte\bibV2-1000.json"
$Data = Get-Content $jsonfile | ConvertFrom-Json
$Data.BIBs += New-Object -TypeName psobject -Property #{$BIB =
#{BIBname=$BIBName},
#{Standort=$Standort},
#{Bücher = #(#{
Buchname=$BuchName;
Autor=$Autor})
}
}
ConvertTo-Json -Depth 50 -InputObject $Data | Out-File $jsonfile}
.$continue
}
$continue = {
Write-Host ""
Write-Host "Was wollen Sie machen?"
Write-Host "(1) Eine weitere Bibliothek hinzufügen"
Write-Host "(2) Einer Bibliothek neue Bücher hinzufügen"
Write-Host "(E) Script beenden"
If (($read = Read-Host ) -eq "1") {
&$start} else {
if (($read) -eq "2") {
. C:\Skripte\büc.ps1 } else {
if (($read) -eq "E") {
exit} else {
Write-Host "+++ FALSCHE EINGABE! Bitte wählen Sie (1) oder (2) für die entsprechende Aktion +++"
.$continue
}
}
}
}
&$start
The output is as follows:
{
"BIBs": [{
"BIB1": [{
"BIBName": "123"
},
{
"Standort": "123"
},
{
"Bücher": [{
"Autor": "123",
"BuchName": "123"
}]
}
]
},
{
"BIB2": [{
"BIBname": "345"
},
{
"Standort": "345"
},
{
"Bücher": [{
"Autor": "345",
"Buchname": "345"
}]
}
]
}
]
}
Now I want to find out the index of "BIB1". I already tried the IndexOf()-Method which should create the output "0" but it gives me "-1" instead, because it can't find the value. How can I get the index of "BIB1"?

Answer 1

Judging by your earlier question, you're attempting to get the index of a specific object so you can access it via its containing array. However, you can do this more directly: $objOfInterest = $Data.BIBs | ? BIB1 - see my answer to your earlier question for details.
You need to iterate over the array elements of $Data.BIBs, which - on reading your serialized-to-a-file-as-JSON hashtables back in with ConvertFrom-Json - are custom objects (as Ansgar correctly points out; they are instances of [System.Management.Automation.PSCustomObject]), and check each for the presence of property 'BIB1':
(In a hashtable, you'd check for the presence of key 'BIB1' with .ContainsKey('BIB1'))
To test the existence of an object property, you need reflection, which is most easily - but somewhat obscurely - achieved via the hidden .PSObject property, as demonstrated in Ansgar Wiechers' more elegant solution.
However, given that the properties of interest have nonempty values, we can infer from the presence of a nonempty value that a given property exists, using implicit Boolean (logic): $obj.'BIB1' by default returns $null if there is no BIB1 property, which is "falsy" in a Boolean context such as an if conditional; conversely, any nonempty value is "truthy":
$propName = 'BIB1'
$i = $ndx = -1
foreach ($obj in $Data.BIBs) {
++$i
if ($obj.$propName) { $ndx = $i; break}
}
$ndx # $ndx now contains the index of the target object or -1 if there was no match

Answer 2

$Date.BIBs is an array of custom objects, not hashtables (since you wrote your original data to a JSON file and then converted that back), so you need something like this:
$arr = $Data.BIBs | ForEach-Object { $_.PSObject.Properties.Name }
$arr.IndexOf('BIB1') # returns 0
$arr.IndexOf('BIB2') # returns 1