finding the character at 'wildcard' position - json

Question

I'm trying to parse a JSON string which has been flattened from a relational dataset from the looks of it... Into a CSV in order to import into an Oracle database. I have name/value pairs similar to this (simplified) example
Device.1.Service.1.Channel.1.someProperty : 1,
Device.1.Service.1.Channel.1.someOtherProperty : "billy",
Device.1.Service.1.Channel.2.someProperty : 8,
Device.1.Service.1.Channel.2.someOtherProperty : "frank",
Device.1.Service.1.Channel.3.someProperty : 12,
Device.1.Service.1.Channel.3.someOtherProperty : "sam",
Device.1.Service.2.Channel.1.someProperty : 3,
Device.1.Service.2.Channel.1.someOtherProperty : "john",
EDIT: A .json file with a similar structure is produced per day per device. So when consolidated (Get-Content .\*.json -Raw) I see the same property names occur many times in console.
As part of the conversion, I'd like parts of the property name to become fields in the database. This will enable us to visualise the data better using dynamic slider filters etc. later.
| Device | Service | Channel | someOtherProperty |
| 1 | 1 | 1 | billy |
| 1 | 1 | 2 | frank |
| 1 | 1 | 3 | sam |
Right now, I'm using the cmdlet ConvertFrom-Json. I'm then selecting the fields (out of nearly 2000 possible fields) using wildcards. The number of channels for example is dynamic.
Get-Content .\*.json -Raw | ConvertFrom-Json |
Select Device.1.Service.1.Channel.?.someOtherProperty
Which returns a PSCustomObject. I'd like to figure out the channel number and use that as a derived field. Pseudo example:
Select #{n="Channel";e={$_.getCharAtWildcard()}},
$_.theValueofTheCurrentObject()
If I pipe the data selected (using wildcard) to Get-Member, the PSCostomObject contains method names as well as my field names (but not the values).
I'm confused about how I access the field name (since 'Name' gives blank rows), then extract the channel number (the character at wildcard position), and then the value to structure my output correctly.
Any pointers? Googled and have a lynda.com sub, but can't seem to find a solution to this specific problem - probably because I'm not using the correct terms?
## ANSGAR's SOLUTION - WORKS FOR SINGLE FILE ##
$dataDir = "C:\ps_json2csv\dummydata"
CD $dataDir
$dict = Get-Content .\*.json -Raw | ConvertFrom-Json | Select -Expand data
$p = 'DvbId'
$re = "frontend\.(\d+)\.logicalchannel\.(\d+)\.service\.(\d+)\..*?\.$p"
## modified regex to match my data, example string: FrontEnd.2.LogicalChannel.3.Service.1.stat.DvbId
$fullset = $dict.PSObject.Properties | Where-Object {
$_.Name -match $re
} | ForEach-Object {
$prop = [ordered]#{
FrontEnd = $matches[1]
LogicalChannel = $matches[2]
Service = $matches[3]
$p = $_.Value
}
New-Object -Type PSObject -Property $prop
}
## inspect $dict - its populated
## inspect $fullset - its empty! :(
Data of which is 2 files contained in C:\ps_json2csv\dummydata :
File1.json
{
"data": {
"Device.1.Service.1.ChannelInfo.Channel.1.Stats.someProperty" : "1",
"Device.1.Service.1.ChannelInfo.Channel.2.Stats.someProperty" : "8",
"Device.1.Service.1.ChannelInfo.Channel.3.Stats.someProperty" : "12",
"FrontEnd.2.LogicalChannel.3.Service.1.stat.DvbId" : "john",
"FrontEnd.2.LogicalChannel.3.Service.2.stat.DvbId" : "billy",
"FrontEnd.2.LogicalChannel.3.Service.3.stat.DvbId" : "frank",
"FrontEnd.2.LogicalChannel.4.Service.1.stat.DvbId" : "sam",
"Device.1.Service.2.ChannelInfo.Channel.1.Stats.someProperty" : "3",
"Some.value.im.not.intersted.in.just.yet": "Sat Jan 1 00:00:00 GMT 0001",
"foo.bar" : "0",
"random.stuff" : "hi there"
}
}
File2.json
{
"data": {
"Device.1.Service.1.ChannelInfo.Channel.1.Stats.someProperty" : "0",
"Device.1.Service.1.ChannelInfo.Channel.2.Stats.someProperty" : "7",
"Device.1.Service.1.ChannelInfo.Channel.3.Stats.someProperty" : "6",
"FrontEnd.2.LogicalChannel.3.Service.1.stat.DvbId" : "john",
"FrontEnd.2.LogicalChannel.3.Service.2.stat.DvbId" : "billy",
"FrontEnd.2.LogicalChannel.3.Service.3.stat.DvbId" : "frank",
"FrontEnd.2.LogicalChannel.4.Service.1.stat.DvbId" : "sam",
"Device.1.Service.2.ChannelInfo.Channel.1.Stats.someProperty" : "4",
"Some.value.im.not.intersted.in.just.yet": "Sun Jan 2 00:00:00 GMT 0001",
"foo.bar" : "0",
"random.stuff" : "hi there"
}
}

Answer 1

I would probably use a regular expression match to filter and extract your data:
$p = 'someOtherProperty'
$re = "device\.(\d+)\.service\.(\d+)\..*?\.channel\.(\d+)\..*?\.$p"
$fullset = $dict.PSObject.Properties | Where-Object {
$_.Name -match $re
} | ForEach-Object {
$prop = [ordered]#{
Device = $matches[1]
Service = $matches[2]
Channel = $matches[3]
$p = $_.Value
}
New-Object -Type PSObject -Property $prop
}

Answer 2

I'd rather convert a string of this syntax into a PSObject with the entire set of your properties. Like this:
$dict=Get-Content .\*.json -Raw | ConvertFrom-Json
$fullset=$dict.psobject.properties | % {
$parse=$_.name.split('.')
$parse+=,$_.value # since JSON values might be non-plain, we need to add the value as single object
$obj=new-object psobject
for ($i=0;$i -lt $parse.length;$i+=2) { # name-value
$v1=$parse[$i]
$v2=$parse[1+$i]
$obj | add-member -type noteproperty -name $v1 -value $v2
}
$obj
}
Then you parse $fullset like you would with a normal list with where {$_.device -eq '1' -and $_.someOtherProperty -ne $null} etc.