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Test-Json

Module:
Microsoft.PowerShell.Utility Module

Tests whether a string is a valid JSON document

Syntax

Default (Default) 

Test-Json
    [-Json] <string>
    [[-Schema] <string>]
    [<CommonParameters>]

Description

The Test-Json cmdlet tests whether a string is a valid JavaScript Object Notation (JSON) document and can optionally verify that JSON document against a provided schema.

The verified string can then be used with the ConvertFrom-Json cmdlet convert a JSON-formatted string to a JSON object, which is easily managed in PowerShell or sent to another program or web service that access JSON input.

Many web sites use JSON instead of XML to serialize data for communication between servers and web-based apps.

This cmdlet was introduced in PowerShell 6.1

Examples

Example 1: Test if an object is valid JSON

This example tests whether the input string is a valid JSON document.

"{'name': 'Ashley', 'age': 25}" | Test-Json

True

Example 2: Test an object against a provided schema

This example takes a string containing a JSON schema and compares it to an input string.

$schema = @'
{
  "definitions": {},
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "http://example.com/root.json",
  "type": "object",
  "title": "The Root Schema",
  "required": [
    "name",
    "age"
  ],
  "properties": {
    "name": {
      "$id": "#/properties/name",
      "type": "string",
      "title": "The Name Schema",
      "default": "",
      "examples": [
        "Ashley"
      ],
      "pattern": "^(.*)$"
    },
    "age": {
      "$id": "#/properties/age",
      "type": "integer",
      "title": "The Age Schema",
      "default": 0,
      "examples": [
        25
      ]
    }
  }
}
'@
"{'name': 'Ashley', 'age': '25'}" | Test-Json -Schema $schema

Test-Json : IntegerExpected: #/age
At line:1 char:37
+ "{'name': 'Ashley', 'age': '25'}" | Test-Json -Schema $schema
+                                     ~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : InvalidData: (:) [Test-Json], Exception
+ FullyQualifiedErrorId : InvalidJsonAgainstSchema,Microsoft.PowerShell.Commands.TestJsonCommand
False

In this example, we get an error because the schema expects an integer for age but the JSON input we tested uses a string value instead.

For more information, see JSON Schema.

Parameters

-Json

Specifies the JSON string to test for validity. Enter a variable that contains the string, or type a command or expression that gets the string. You can also pipe a string to Test-Json.

The Json parameter is required.

Parameter properties

Type:String
Default value:None
Supports wildcards:False
DontShow:False

Parameter sets

(All)
Position:1
Mandatory:True
Value from pipeline:True
Value from pipeline by property name:False
Value from remaining arguments:False

-Schema

Specifies a Schema to validate the JSON input against. If passed Test-Json will validate that the Json input conforms to the spec specified by the Schema parameter and return $True only if the input conforms to the provided Schema.

For more information, see JSON Schema.

Parameter properties

Type:String
Default value:None
Supports wildcards:False
DontShow:False

Parameter sets

(All)
Position:2
Mandatory:False
Value from pipeline:False
Value from pipeline by property name:False
Value from remaining arguments:False

CommonParameters

This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutBuffer, -OutVariable, -PipelineVariable, -ProgressAction, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters.

Inputs

String

You can pipe a JSON string to Test-Json.

Outputs

Boolean

Notes

The Test-Json cmdlet is implemented by using the NJsonSchema Class.