Powershell: ConvertFrom-Json fails to parse project.lock.json

[SteveL-MSFT]

$json = gc project.lock.json -Raw
ConvertFrom-Json $json

Expected: PowerShell should be able to parser the json data.
Actual: A useless error message which does not tell me what went wrong

ConvertFrom-Json : Cannot process argument because the value of argument "name" is not valid. Change the value of the
"name" argument and run the operation again.
At line:1 char:1
- ConvertFrom-Json $json
- ~~~~~~~~~~~~~~~~~~~~~~
  - CategoryInfo          : InvalidArgument: (:) [ConvertFrom-Json], PSArgumentException
  - FullyQualifiedErrorId : Argument,Microsoft.PowerShell.Commands.ConvertFromJsonCommand

[kittholland]

Bug is due to empty name for json dictionary entry, which appears to be valid by json standards, issue I believe is when converting to psobject:

Example from the project.lock.json:

"projectFileDependencyGroups": {
"": [
"System.Management.Automation >= 6.0.0-*"
],

thrown from line 4474 in MshMemberInfo.cs

                if (String.IsNullOrEmpty(name))
                {
                    throw PSTraceSource.NewArgumentException("name");
                }

"Cannot process argument because the value of argument "name" is not valid. Change the value of the "name" argument and run the operation again."

Reproducible with the following simple json:

{
"": "Test"
}

I am uncertain how to proceed further to fix this issue, hopefully this helps.

[SteveL-MSFT]

@kittholland thanks for looking into this, best as I can tell per http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf, an empty string as the name is allowed and works in javascript. I guess the next step is to determine if the issue is in newtonsoft json parser.

[kittholland]

From what I could see in the debugger, newtonsoft was OK with it, but converting the Jobject into a PSObject failed because the name was empty.

[SteveL-MSFT]

Ok, that makes sense (on why it failed). A HashTable will accept an empty string key, so it seems we should have PSObject support it as well. @kittholland are you going to work on a fix?

[kittholland]

I have not looked deeply into what would be required, but I can give it a try.

[joeyaiello]

We should also handle the Invoke-WebRequest/Invoke-RestMethod scenario where you're able to post a null JSON key as a string or as an object.

[joeyaiello]

@SteveL-MSFT I think we still need to fix this one for 6.0.0. Valid JSON should be parsed by ConvertFrom-Json.

[kittholland]

One other issue related to this is Invoke-Restmethod will silently fail and return null for valid json that is not PSCustomObject compatible.

This can be caused by NULL keys or case sensitive keys.

[SteveL-MSFT]

@kittholland are you still working on this or should I take it?

[kittholland]

@SteveL-MSFT I think I'm out of my depth on a solution for this. Thanks to whoever takes it from here.

[SteveL-MSFT]

Forgot about the discussion in https://github.com/PowerShell/PowerShell/pull/2820. Introducing a json specific type isn't happening in 6.0.0 timeframe.

[bergmeister]

@SteveL-MSFT Can this issue be closed since PR #5043 provides a workaround via the -AsHashTable switch?

[SteveL-MSFT]

@bergmeister agree!

[DarwinJS]

Any work arounds to this without upgrading PowerShell?

[kittholland]

@DarwinJS You can either modify your json to be compatible with PSObjects, or you will need to modify/create a cmdlet to convert from json into hashtables.

[bergmeister]

@DarwinJS Since PowerShell Core is side by side and you can even get a self-contained version, you could just call into a newer version of pwsh from an old version of pwsh.

[DarwinJS]

This is part of tooling that runs on thousands of machines I don't control and actually needs to be a single script with no public repo dependencies - so I resorted to the -replace method. Thanks.