Add a flag to output a single line in `ConvertTo-YAML`.

[RokeJulianLockhart]

Suggestion

Sometimes, I want the YAML to be a single line, because some input forms solely permit that.

Cuurent Status

The current documentation doesn't indicate a way to accomplish this:

1. (Get-Help -Name 'ConvertTo-YAML').syntax.syntaxItem.parameter | Format-List

2. name             : Data
   required         : false
   pipelineInput    : true (ByValue)
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   parameterValue   : Object
   type             : @{name=Object}
   position         : 0
   aliases          : None
   
   name             : OutFile
   required         : false
   pipelineInput    : false
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   parameterValue   : string
   type             : @{name=string}
   position         : Named
   aliases          : None
   
   name             : JsonCompatible
   required         : false
   pipelineInput    : false
   isDynamic        : false
   globbing         : false
   parameterSetName : NoOptions
   type             : @{name=switch}
   position         : Named
   aliases          : None
   
   name             : KeepArray
   required         : false
   pipelineInput    : false
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   type             : @{name=switch}
   position         : Named
   aliases          : None
   
   name             : Force
   required         : false
   pipelineInput    : false
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   type             : @{name=switch}
   position         : Named
   aliases          : None
   
   name             : Data
   required         : false
   pipelineInput    : true (ByValue)
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   parameterValue   : Object
   type             : @{name=Object}
   position         : 0
   aliases          : None
   
   name             : OutFile
   required         : false
   pipelineInput    : false
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   parameterValue   : string
   type             : @{name=string}
   position         : Named
   aliases          : None
   
   name                : Options
   required            : false
   pipelineInput       : false
   isDynamic           : false
   globbing            : false
   parameterSetName    : Options
   parameterValue      : SerializationOptions
   type                : @{name=SerializationOptions}
   position            : Named
   aliases             : None
   parameterValueGroup : @{parameterValue=System.Object[]}
   
   name             : KeepArray
   required         : false
   pipelineInput    : false
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   type             : @{name=switch}
   position         : Named
   aliases          : None
   
   name             : Force
   required         : false
   pipelineInput    : false
   isDynamic        : false
   globbing         : false
   parameterSetName : (All)
   type             : @{name=switch}
   position         : Named
   aliases          : None

[gabriel-samfira]

Could you give an example of what you mean by having the output as a single line?

[RokeJulianLockhart]

#147 (comment)

@gabriel-samfira, https://stackoverflow.com/revisions/67645180/2#:~:text=networkMapping:%20%7B'test_net_1':%20%7B'external':%20true%7D%2C%20'test_net_2':%20%7B'external':%20true%7D%2C%20'test_net_3':%20%7B'external':%20true%7D%7D provides an example:

networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'external': true}, 'test_net_3': {'external': true}}

...which, surprisingly, doesn't appear to be supported whatsoever by this library:

PS /home/RokeJulianLockhart> networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'external': true}, 'test_net_3': {'external': true}} | ConvertFrom-YAML
ParserError: 
Line |
   1 |  networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'ex …
     |                               ~
     | Unexpected token ':' in expression or statement.
PS /home/RokeJulianLockhart> Get-Error

Type        : System.Management.Automation.ParseException
Errors      : 
    Extent  : :
    ErrorId : UnexpectedToken
    Message : Unexpected token ':' in expression or statement.

    Extent  : :
    ErrorId : UnexpectedToken
    Message : Unexpected token ':' in expression or statement.

    Extent  : :
    ErrorId : UnexpectedToken
    Message : Unexpected token ':' in expression or statement.

    Extent  : :
    ErrorId : UnexpectedToken
    Message : Unexpected token ':' in expression or statement.
Message     : At line:1 char:30
              + networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'ex …
              +                              ~
              Unexpected token ':' in expression or statement.
              
              At line:1 char:43
              + networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'ex …
              +                                           ~
              Unexpected token ':' in expression or statement.
              
              At line:1 char:77
              + … {'test_net_1': {'external': true}, 'test_net_2': {'external': true},  …
              +                                                               ~
              Unexpected token ':' in expression or statement.
              
              At line:1 char:111
              + …  'test_net_2': {'external': true}, 'test_net_3': {'external': true}}  …
              +                                                               ~
              Unexpected token ':' in expression or statement.
ErrorRecord : 
    Exception             : 
        Type    : System.Management.Automation.ParentContainsErrorRecordException
        Message : At line:1 char:30
                  + networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'ex …
                  +                              ~
                  Unexpected token ':' in expression or statement.
                  
                  At line:1 char:43
                  + networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'ex …
                  +                                           ~
                  Unexpected token ':' in expression or statement.
                  
                  At line:1 char:77
                  + … {'test_net_1': {'external': true}, 'test_net_2': {'external': true},  …
                  +                                                               ~
                  Unexpected token ':' in expression or statement.
                  
                  At line:1 char:111
                  + …  'test_net_2': {'external': true}, 'test_net_3': {'external': true}}  …
                  +                                                               ~
                  Unexpected token ':' in expression or statement.
        HResult : -2146233087
    CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordException
    FullyQualifiedErrorId : UnexpectedToken
    InvocationInfo        : 
        ScriptLineNumber : 1
        OffsetInLine     : 30
        HistoryId        : 2
        Line             : networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'external': true}, 'test_net_3': {'external': true}} | ConvertFrom-YAML
        Statement        : :
        PositionMessage  : At line:1 char:30
                           + networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'ex …
                           +                              ~
        CommandOrigin    : Internal
TargetSite  : 
    Name          : Invoke
    DeclaringType : [System.Management.Automation.Runspaces.PipelineBase]
    MemberType    : Method
    Module        : System.Management.Automation.dll
Source      : System.Management.Automation
HResult     : -2146233087
StackTrace  : 
   at System.Management.Automation.Runspaces.PipelineBase.Invoke(IEnumerable input)
   at Microsoft.PowerShell.Executor.ExecuteCommandHelper(Pipeline tempPipeline, Exception& exceptionThrown, ExecutionOptions options)

[skycommand]

@RokeJulianLockhart That's because your PowerShell command is not well-formed.

The correct command is this:

$TestYaml = "networkMapping: {'test_net_1': {'external': true}, 'test_net_2': {'external': true}, 'test_net_3': {'external': true}}" | ConvertFrom-Yaml

Now you can inspect the resulting object:

$TestYaml

Name                           Value
----                           -----
networkMapping                 {[test_net_3, System.Collections.Hashtable], [test_net_2, System.Collections.Hashtable], [test_net_1, System.Collections.Hashtable]}

$TestYaml.networkMapping

Name                           Value
----                           -----
test_net_3                     {[external, True]}
test_net_2                     {[external, True]}
test_net_1                     {[external, True]}

[RokeJulianLockhart]

#147 (comment)

Apologies, @skycommand. That was stupid of me. Shouldn't be filing bugs at midnight.

[gabriel-samfira]

That's okay @RokeJulianLockhart ! Happened to me more than once. Glad things got sorted out. Closing this bug.

[RokeJulianLockhart]

#147 (comment)

@gabriel-samfira, the issue hasn't been solved! That was an aside. This issue requests the ability to output a single line. Instructing ConvertTo-YAML to do so still isn't possible.

[gabriel-samfira]

Have you tried the -JsonCompatible flag? It will output json in one line. Jdon being a subset of yaml, you should then be able to parse it with any other library.

[RokeJulianLockhart]

#147 (comment)

@gabriel-samfira, thanks. However, having it in one line merely because it's JSON-compatible, instead of prettified like usual, doesn't seem to make much sense.

Irrespective, I want to use YAML because it's more readable, even on a single line. Outputting JSON-compatible YAML rather nullifies that.

[gabriel-samfira]

So, this example:

$TestYaml = 'networkMapping: {"test_net_1": {"external": true}, "test_net_2": {"external": true}, "test_net_3": {"external": true}}'

is equivalent to:

$TestYaml = '{"networkMapping": {"test_net_1": {"external": true}, "test_net_2": {"external": true}, "test_net_3": {"external": true}}}'

In your example, you essentially have a JSON assigned to networkMapping. The only thing I added was an opening and closing bracket. And quotes around networkMapping. The rest is identical.

There is no flow style in yaml that gives you a one liner from a data structure that has nested data structures like arrays, maps, etc. Not unless you use json which allows you to have one line. YAML depends on newlines and indents if you want actual yaml. The only places where it doesn't is where you use JSON (which is a subset of yaml).

As an example, here is how python does it. First, with default_flow_style=False. This will output YAML:

# With default_flow_style=False
>>> import yaml
>>> data = {"a": [1, 2, 3], "b": {"c": 7}}
>>> print(yaml.dump(data, default_flow_style=False))
a:
- 1
- 2
- 3
b:
  c: 7

Now let's try with default_flow_style=True:

>>> import yaml
>>> data = {"a": [1, 2, 3], "b": {"c": 7}}
>>> print(yaml.dump(data,default_flow_style=True))
{a: [1, 2, 3], b: {c: 7}}

>>> 

We essentially got a JSON. The only thing missing from that YAML output are the quotes around the keys. But it looks just as unfriendly as any other JSON.

[gabriel-samfira]

Don't get me wrong, I am willing to add a flag to enable the Flow style instead of the Block style, but I am not sure it adds much value. Let me know if you really need it and I can add it in the next round of updates.

[gabriel-samfira]

See if #148 suits your needs. It's still a WiP because I also need to write tests, but it should do what you need.