问题
I am trying to create a table from a JSON file I am receiving from a RESTful API.
When I print the property of the json object I get an output like this:
PS> Write-Output JSON.Object
Object1 : @{key1=property; key2=property; key3=property; key4=property}
Object2 : @{key1=property; key2=property; key3=property; key4=property}
Object3 : @{key1=property; key2=property; key3=property; key4=property}
Object4 : @{key1=property; key2=property; key3=property; key4=property}
The output I would like to see is this:
Name key1 key2 key3 key4 ----- ---- ---- ---- ---- Object1 property property property property Object2 property property property property Object3 property property property property
In addition, is it possible to avoid displaying a specific key and it's properties?
Example:
Name key1 key2 key4 # ← Not displaying key3 ----- ---- ---- ---- Object1 property property property Object2 property property property Object3 property property property
回答1:
You need to add the parent keyname as a property Name to the nested objects:
$json.Object | ForEach-Object {
foreach ($p in $_.PSObject.Properties) {
$p.Value | Select-Object @{n='Name';e={$p.Name}},*
}
}
Note that PowerShell will render the output in list form by default, since your objects have more than 4 properties. Pipe it through Format-List -AutoSize to get tabular output.
回答2:
To complement Ansgar Wiecher's elegant answer with background information:
Let's define sample input that simulates a single, nested object converted to a PowerShell [pscustomobject] instance via ConvertFrom-Json:
$objFromJson = [pscustomobject] @{
Object1 = [pscustomobject] @{key1='o11'; key2='o12'; key3='o13'; key4='o14'}
Object2 = [pscustomobject] @{key1='o21'; key2='o22'; key3='o23'; key4='o24'}
Object3 = [pscustomobject] @{key1='o31'; key2='o32'; key3='o33'; key4='o34'}
Object4 = [pscustomobject] @{key1='o41'; key2='o42'; key3='o43'; key4='o44'}
Object5 = [pscustomobject] @{key1='o51'; key2='o52'; key3='o53'; key4='o54'}
}
Outputting $objFromJson gives output that is formatted as in the question.
Why does this result in the output formatting shown in the question?
For types such as [pscustomobject], which do not have explicit formatting definitions defined for them (via *.ps1xml files and loaded implicitly into the session or explicitly via Update-FormatData), PowerShell decides what default formatting to use based on the number of properties of the type:
- A type with up to 4 properties implicitly uses
Format-Table - a type with 5 or more properties implicitly uses
Format-List
The sample input in the question is presumably abridged; with truly only 4 properties, a tabular display would have resulted.
The properties themselves are rendered by calling .PSObject.ToString() on their values, which is typically the same representation you'd get if you referenced the object inside a double-quoted string, except that the latter always uses culture-invariant formatting, whereas .ToString() will respect the current culture, if the type supports it.
In the case of a [pscustomobject] instance, this results in a representation that resembles a hashtable literal, but isn't one (for background information, see this answer); e.g.:
PS> $objFromJson.Object1.PSObject.ToString()
@{key1=o11; key2=o12; key3=o13; key4=o14}
Reshaping the data as desired:
There is no way to use formatting cmdlets such as Format-Table directly to yield the desired output - the data must be reshaped first:
Specifically, the properties of object $objFromJson must be reshaped into a collection of custom objects:
whose
Nameproperty contains the name of a given property, andwhose other properties are the properties of the object of that property's value; in other words: the properties of the input property's value must be made properties of the output object itself.
Extracting $objFromJson's properties is facilitated by PowerShell adding (among others) a hidden .PSObject property to all objects, whose own .Properties property contains a collection of all the object's property definitions (name, value, additional metadata such as the type of property, ...); e.g.:
PS> $objFromJson.Object1.PSObject.Properties
MemberType : NoteProperty
IsSettable : True
IsGettable : True
Value : o11
TypeNameOfValue : System.String
Name : key1
IsInstance : True
# ... remaining properties
Outputting the collection of $objFromJson's property definitions and extracting only the definitions' Name and Value properties is a step in the right direction:
PS> $objFromJson.PSObject.Properties | Select-Object Name, Value
Name Value
---- -----
Object1 @{key1=o11; key2=o12; key3=o13; key4=o14}
Object2 @{key1=o21; key2=o22; key3=o23; key4=o24}
Object3 @{key1=o31; key2=o32; key3=o33; key4=o34}
Object4 @{key1=o41; key2=o42; key3=o43; key4=o44}
Object5 @{key1=o51; key2=o52; key3=o53; key4=o54}
However, we must make the properties of the .Value property direct properties of the output objects to get output with property-individual values.
Ansgar's elegant answer demonstrates how to do that in a single pipeline.
Let me complement it with a reusable helper function derived from it:
function ConvertTo-Collection($InputObject) {
foreach ($obj in $InputObject) {
foreach ($prop in $obj.PSObject.Properties) {
$prop.Value | Select-Object @{ n='Name'; e={ $prop.Name }}, *
}
}
}
With that function in place, the desired output can now be achieved thus:
ConvertTo-Collection $objFromJson | Format-Table
To exclude a specific property, such as key3:
ConvertTo-Collection $objFromJson | Select-Object -ExcludeProperty key3 |
Format-Table
来源：https://stackoverflow.com/questions/41089151/format-pscustomobject-instances-returned-by-invoke-restmethod-or-convertfrom-j