JsonFS

Mounts an existing JSON file as PowerShell drive for editing with the PowerShell *-Itemand *-ItemProperty commands.

Install from PowerShell Gallery

The current version of JsonFs can be downloaded form PowerShell Gallery or install with a PowerShellGet command:

Install-Module JsonFS

Building the Module

To build the module just publish the project with the dotnet CLI

dotnet publish .\src\TreeStore.JsonFS\

The implementation depends on base classes from TreeStore.Core

An Example Module

The folder example contains an small powershell module which is using TreeStore.JsonFS as its persistence. It stores provides directory aliases in a json file.

Mounting a JSON File

To mount a json file test.json use the command:

Import-Module TreeStore.JsonFs
New-PSDrive -PSProvider "JsonFs" -Name json -Root "./test.json"

The provider won't create the JSON file nor will it create missing directories in the Root path. The current location can be set to the JSON drive with the Set-Location command.

cd json:\

The provider also creates a global function for setting the current location to the JsonFS drive:

json: <Return>

A JsonFS drive only knows container nodes (directories). All JSON objects are shown as containers, all JSON properties having a non-scalar value type are shown as child containers. All JSON properties having a scalar value type (number, string etc) are shown as PowerShell properties of the file system item.

For arrays a similar semantic is applied: if the first value of an array is a scalar value the whole array is shows as property value. If the first item of the array is an object type the array is show as a collection of child containers having names "0","1",...

A JSON object like this..

{
    "object": {
        "value1" : 1,
        "text1" : "text1"
    },
    "value2":2.0
    "text2":"text2"
}

..would create a file system with:

• object: a sub directory of the Root when calling Get-ChildItem -Path /
• object.value1, object.text1: properties of the item when calling Get-Item -Path /object
• value2, text2: properties of the root item when calling Get-Item -Path /

Accessing JSON Filesystem Nodes

The common PowerShell *-Item-Commands can be used to modify the JSON filesystem and with it the underlying JSON file. Changes are made persistent immediately. Implemented are:

• Clear-Item: remove JSON node content
• Copy-Item: create a copy of JSON node at another place of the JSON filesystem
• Get-Item: PSObject from a JSON node
• Move-Item: unlink the JSON node from its current parent and link as a child to another parent node
• New-Item: create a node child JSON node
• Remove-Item: remove a JSON node completely, including child nodes (-Recurse)
• Rename-Item: change the property name of a JSON node at its parent
• Set-Item: replace the a JSON nodes value properties wit a new set of value properties

Also properties may be modified using PowerShell *-ItemProperty commands. Implemented are:

• Clear-ItemProperty: clear a properties content
• Copy-ItemProperty: clone the property at another node and/or with a new name
• Get-ItemProperty: get a JSON properties value
• Move-ItemProperty: move a property to another JSON node
• New-ItemProperty: create a new property
• Remove-ItemProperty: remove a property from a JSON node
• Rename-ItemProperty: change the name of a JSON property
• Set-ItemProperty: ste the value of a JSON property (-Force creates a new property)

Copy JSON data between two instances of the JsonFS provider

It is possible to copy a Container (recursively or not) to another JsonFS drive:

Copy-Item -Path json-1:\parent\child -Destination json-2:\another\container -Recurse

Also moving is implemented between to JSON file systems

Splatting Value Properties

For configuration scenarios it is possible to retrieve the value properties of a JSON node as a hash table for splatting:

$parameters = Get-Item json:\path\to\node -AsHashtable

Any-Powershell-Function @parameters

Working with JSON Schemas

JsonFs supports JSON Schema validation before writing changes nack to the JSON file. A Schema may be supplied either by a parameter while drive creation or from with the JSON file.

New-PSDrive -PSProvider "JsonFs" -Name json -Root "./test.json" -JsonSchema ./test-schema.json

From within the json file the Uri must ether be a rooted file: scheme or an web address using http: or https:. The $schemaattribute is expected in the root node of the JSON document.

{
    "$schema":"file:///c:/data/test.json"
}

If the schema validation fails the change is thrown away ad the the file is reread from the disk.

Releases

• 0.1.0: first release
• 0.2.0:
  • Set-Item: replaces all value properties, doesn't touch child properties
  • New-Item: like Set-Item, only value properties are created
• 0.3.0:
  • Support for Get-/Set-/Clear-Content cmdlets using JSON text added
  • fs items have base object of type 'JsonFsItem'
    • having a property 'Name'
    • having a property 'PropertyName' with all value property names
  • format for fs items
    • table format with Columns 'Name' and 'PropertyNames'.
  • improvements with value arrays: value array are converted from object[] provider by powershell from @(..)
• 0.4.0:
  • create global function <drive name>: to change location to newly created JsonFS drive
• 0.5.0:
  • Support for splatting with Get-Item -AsHashtable
  • Set-ItemProperty raise exception if property is unkwoen and -Force is not given
  • New-Item with hash table value New-Item -Value @ { key = "value" }
  • Set-Item with hash table value Set-Item -Value @ { key = "value" }
• v0.5.1:
  • Updates dependencies (.Net7)
  • Uses PSChildName as default name property to avoid overlapping with a custom name-property
• v0.5.2:
  • fixes linux by updating TreeStore.Core to v0.5.0
• v0.6.0:
  • validates JSON schema before writing to file.
• v0.6.1:
  • replaces JSON.Net schema with NJsonSchema b/c of licensing
• v0.7.0:
  • Set-Item and New-Item accept class instances (internal conversion to PSObject)