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ConvertFrom-Json

  • Reference
Module:
Microsoft.PowerShell.Utility

Converts a JSON-formatted string to a custom object or a hash table.

Syntax

ConvertFrom-Json
                [-InputObject] <String>
                [-AsHashtable]
                [-Depth <Int32>]
                [-NoEnumerate]
                [<CommonParameters>]

Description

The ConvertFrom-Json cmdlet converts a JavaScript Object Notation (JSON) formatted string to a custom PSObject or Hashtable object that has a property for each field in the JSON string. JSON is commonly used by web sites to provide a textual representation of objects. The cmdlet adds the properties to the new object as it processes each line of the JSON string.

The JSON standard allows duplicate key names, which are prohibited in PSObject and Hashtable types. For example, if the JSON string contains duplicate keys, only the last key is used by this cmdlet. See other examples below.

To generate a JSON string from any object, use the ConvertTo-Json cmdlet.

This cmdlet was introduced in PowerShell 3.0.

Note

Beginning with PowerShell 6, the cmdlet supports JSON with comments. JSON comments start with two forward slashes (//) characters. JSON comments aren't captured in the objects output by the cmdlet. Prior to PowerShell 6, ConvertFrom-Json would return an error when it encountered a JSON comment.

Examples

Example 1: Convert a DateTime object to a JSON object

This command uses the ConvertTo-Json and ConvertFrom-Json cmdlets to convert a DateTime object from the Get-Date cmdlet to a JSON object then to a PSCustomObject.

Get-Date | Select-Object -Property * | ConvertTo-Json | ConvertFrom-Json

DisplayHint : 2
DateTime    : Friday, January 13, 2012 8:06:31 PM
Date        : 1/13/2012 8:00:00 AM
Day         : 13
DayOfWeek   : 5
DayOfYear   : 13
Hour        : 20
Kind        : 2
Millisecond : 400
Minute      : 6
Month       : 1
Second      : 31
Ticks       : 634620819914009002
TimeOfDay   : @{Ticks=723914009002; Days=0; Hours=20; Milliseconds=400; Minutes=6; Seconds=31; TotalDays=0.83786343634490734; TotalHours=20.108722472277776; TotalMilliseconds=72391400.900200009; TotalMinutes=1206.5233483366667;TotalSeconds=72391.4009002}
Year        : 2012

The example uses the Select-Object cmdlet to get all of the properties of the DateTime object. It uses the ConvertTo-Json cmdlet to convert the DateTime object to a string formatted as a JSON object and the ConvertFrom-Json cmdlet to convert the JSON-formatted string to a PSCustomObject object.

Example 2: Get JSON strings from a web service and convert them to PowerShell objects

This command uses the Invoke-WebRequest cmdlet to get JSON strings from a web service and then it uses the ConvertFrom-Json cmdlet to convert JSON content to objects that can be managed in PowerShell.

# Ensures that Invoke-WebRequest uses TLS 1.2
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
$j = Invoke-WebRequest 'https://api.github.com/repos/PowerShell/PowerShell/issues' | ConvertFrom-Json

You can also use the Invoke-RestMethod cmdlet, which automatically converts JSON content to objects.

Example 3: Convert a JSON string to a custom object

This example shows how to use the ConvertFrom-Json cmdlet to convert a JSON file to a PowerShell custom object.

Get-Content -Raw JsonFile.JSON | ConvertFrom-Json

The command uses Get-Content cmdlet to get the strings in a JSON file. The Raw parameter returns the whole file as a single JSON object. Then it uses the pipeline operator to send the delimited string to the ConvertFrom-Json cmdlet, which converts it to a custom object.

Example 4: Convert a JSON string to a hash table

This command shows an example where the -AsHashtable switch can overcome limitations of the command.

'{ "key":"value1", "Key":"value2" }' | ConvertFrom-Json -AsHashtable

The JSON string contains two key value pairs with keys that differ only in casing. Without the switch, the command would have thrown an error.

Example 5: Round-trip a single element array

This command shows an example where the -NoEnumerate switch is used to round-trip a single element JSON array.

Write-Output "With -NoEnumerate: $('[1]' | ConvertFrom-Json -NoEnumerate | ConvertTo-Json -Compress)"
Write-Output "Without -NoEnumerate: $('[1]' | ConvertFrom-Json | ConvertTo-Json -Compress)"

With -NoEnumerate: [1]
Without -NoEnumerate: 1

The JSON string contains an array with a single element. Without the switch, converting the JSON to a PSObject and then converting it back with the ConvertTo-Json command results in a single integer.

Parameters

-AsHashtable

Converts the JSON to a hash table object. This switch was introduced in PowerShell 6.0. There are several scenarios where it can overcome some limitations of the ConvertFrom-Json cmdlet.

  • Without this switch, when two or more keys in a JSON object are case-insensitively identical, they are treated as identical keys. In that case, only the last of those case-insensitively identical keys is included in the converted object.
  • Without this switch, the cmdlet throws an error whenever the JSON contains a key that's an empty string. PSCustomObject can't have property names that are empty strings. For example, this can occur in project.lock.json files.
  • Hash tables can be processed faster for certain data structures.
Type:SwitchParameter
Position:Named
Default value:False
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-Depth

Gets or sets the maximum depth the JSON input is allowed to have. The default is 1024.

This parameter was introduced in PowerShell 6.2.

Type:Int32
Position:Named
Default value:None
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-InputObject

Specifies the JSON strings to convert to JSON objects. Enter a variable that contains the string, or type a command or expression that gets the string. You can also pipe a string to ConvertFrom-Json.

The InputObject parameter is required, but its value can be an empty string. When the input object is an empty string, ConvertFrom-Json doesn't generate any output. The InputObject value can't be $null.

Type:String
Position:0
Default value:None
Required:True
Accept pipeline input:True
Accept wildcard characters:False

-NoEnumerate

Specifies that output isn't enumerated.

Setting this parameter causes arrays to be sent as a single object instead of sending every element separately. This guarantees that JSON can be round-tripped via ConvertTo-Json.

Type:SwitchParameter
Position:Named
Default value:False
Required:False
Accept pipeline input:False
Accept wildcard characters:False

Inputs

String

You can pipe a JSON string to ConvertFrom-Json.

Outputs

PSCustomObject

Hashtable

Notes

This cmdlet is implemented using Newtonsoft Json.NET.

Beginning in PowerShell 6, ConvertTo-Json attempts to convert strings formatted as timestamps to DateTime values. The converted value is a [datetime] instance with a Kind property set as follows:

  • Unspecified, if there is no time zone information in the input string.
  • Utc, if the time zone information is a trailing Z.
  • Local, if the time zone information is given as a trailing UTC offset like +02:00. The offset is properly converted to the caller's configured time zone. The default output formatting doesn't indicate the original time zone offset.

The PSObject type maintains the order of the properties as presented in the JSON string. While the key-value pairs are added to the Hashtable in the order presented in the JSON string, Hashtable objects don't maintain that order.