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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 PSCustomObject 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 JSON standard does not prohibit usage that is prohibited with a PSCustomObject. 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, this cmdlet supports JSON with comments. Accepted comments are started with two forward slashes (//). The comment will not be represented in the data and can be written in the file without corrupting the data or throwing an error as it did in PowerShell 5.1.

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 JsonFile.JSON | ConvertFrom-Json

The command uses Get-Content cmdlet to get the strings in a JSON file. 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.

  • If the JSON contains a list with keys that only differ in casing. Without the switch, those keys would be seen as identical keys and therefore only the last one would get used.
  • If the JSON contains a key that is an empty string. Without the switch, the cmdlet would throw an error since a PSCustomObject does not allow for that but a hash table does. An example use case where this can occurs are 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. By default, it 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 does not generate any output. The InputObject value cannot be $null.

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

-NoEnumerate

Specifies that output is not 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 does not indicate the original time zone offset.