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James Brundage
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Adding JSONSchema transpiler (Fixes #274)
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‎Transpilers/Protocols/JSONSchema.Protocol.psx.ps1‎

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<#
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.SYNOPSIS
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json schema protocol
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.DESCRIPTION
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Converts a json schema to PowerShell.
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.EXAMPLE
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jsonschema https://aka.ms/terminal-profiles-schema#/$defs/Profile
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#>
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[ValidateScript({
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$commandAst = $_
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if ($commandAst.CommandElements.Count -eq 1) { return $false }
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# If neither command element contained a URI
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if (-not ($commandAst.CommandElements[1].Value -match '^https{0,1}://')) {
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return $false
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}
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return ($commandAst.CommandElements[0].Value -in 'schema', 'jsonschema')
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})]
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[Alias('JSONSchema')]
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param(
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# The URI.
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[Parameter(Mandatory,ValueFromPipeline,ParameterSetName='Protocol')]
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[Parameter(Mandatory,ParameterSetName='ScriptBlock')]
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[uri]
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$SchemaUri,
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# The Command's Abstract Syntax Tree
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[Parameter(Mandatory,ParameterSetName='Protocol')]
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[Management.Automation.Language.CommandAST]
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$CommandAst,
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[Parameter(Mandatory,ParameterSetName='ScriptBlock',ValueFromPipeline)]
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[scriptblock]
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$ScriptBlock = {},
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# One or more property prefixes to remove.
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# Properties that start with this prefix will become parameters without the prefix.
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[Alias('Remove Property Prefix')]
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[string[]]
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$RemovePropertyPrefix,
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# One or more properties to ignore.
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# Properties whose name or description is like this keyword will be ignored.
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[Alias('Ignore Property', 'IgnoreProperty','SkipProperty', 'Skip Property')]
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[string[]]
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$ExcludeProperty,
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# One or more properties to include.
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# Properties whose name or description is like this keyword will be included.
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[Alias('Include Property')]
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[string[]]
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$IncludeProperty,
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# If set, will not mark a parameter as required, even if the schema indicates it should be.
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[Alias('NoMandatoryParameters','No Mandatory Parameters', 'NoMandatories', 'No Mandatories')]
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[switch]
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$NoMandatory
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)
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begin {
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# First we declare a few filters we will reuse.
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# One resolves schema definitions.
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# The inputObject is the schema.
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# The arguments are the path within the schema.
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filter resolveSchemaDefinition
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{
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$in = $_.'$defs'
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$schemaPath = $args -replace '^#' -replace '^/' -replace '^\$defs' -split '[/\.]' -ne ''
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foreach ($sp in $schemaPath) {
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$in = $in.$sp
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}
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$in
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}
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# Another converts property names into schema parameter names.
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filter getSchemaParameterName {
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$parameterName = $_
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# If we had any prefixes we wished to remove, now is the time.
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if ($RemovePropertyPrefix) {
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$parameterName = $parameterName -replace "^(?>$(@($RemovePropertyPrefix) -join '|'))"
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if ($property.Name -like 'Experimental.*') {
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$null = $null
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}
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}
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# Any punctuation followed by a letter should be removed and replaced with an Uppercase letter.
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$parameterName = [regex]::Replace($parameterName, "\p{P}(\p{L})", {
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param($match)
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$match.Groups[1].Value.ToUpper()
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}) -replace '\p{P}'
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# And we should force the first letter to be uppercase.
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$parameterName.Substring(0,1).ToUpper() + $parameterName.Substring(1)
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}
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# If we have not cached the schema uris, create a collection for it.
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if (-not $script:CachedSchemaUris) {
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$script:CachedSchemaUris = @{}
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}
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$myCmd = $MyInvocation.MyCommand
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}
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process {
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# If we are being invoked as a protocol
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if ($PSCmdlet.ParameterSetName -eq 'Protocol') {
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# we will parse our input as a sentence.
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$mySentence = $commandAst.AsSentence($MyInvocation.MyCommand)
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# Walk thru all mapped parameters in the sentence
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$myParams = [Ordered]@{} + $PSBoundParameters
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foreach ($paramName in $mySentence.Parameters.Keys) {
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if (-not $myParams.Contains($paramName)) { # If the parameter was not directly supplied
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$myParams[$paramName] = $mySentence.Parameters[$paramName] # grab it from the sentence.
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foreach ($myParam in $myCmd.Parameters.Values) {
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if ($myParam.Aliases -contains $paramName) { # set any variables that share the name of an alias
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$ExecutionContext.SessionState.PSVariable.Set($myParam.Name, $mySentence.Parameters[$paramName])
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}
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}
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# and set this variable for this value.
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$ExecutionContext.SessionState.PSVariable.Set($paramName, $mySentence.Parameters[$paramName])
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}
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}
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}
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# We will try to cache the schema URI at a given scope.
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$script:CachedSchemaUris[$SchemaUri] = $schemaObject =
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if (-not $script:CachedSchemaUris[$SchemaUri]) {
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Invoke-RestMethod -Uri $SchemaUri
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} else {
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$script:CachedSchemaUris[$SchemaUri]
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}
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# If we do not have a schema object, error out.
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if (-not $schemaObject) {
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Write-Error "Could not get Schema from '$schemaUri'"
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return
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}
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# If the object does not look have a JSON schema, error out.
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if (-not $schemaObject.'$schema') {
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Write-Error "'$schemaUri' is not a JSON Schema"
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return
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}
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# If we do not have a URI fragment or there are no properties
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if (-not $SchemaUri.Fragment -and -not $schemaObject.properties) {
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Write-Error "No root properties defined and no definition specified"
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return # error out.
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}
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# Resolve the schema object we want to generate.
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$schemaDefinition =
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if (-not $schemaObject.properties -and $SchemaUri.Fragment) {
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$schemaObject | resolveSchemaDefinition $SchemaUri.Fragment
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} else {
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$schemaObject.properties
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}
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# Start off by carrying over the description.
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$newPipeScriptSplat = @{
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description = $schemaDefinition.description
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}
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# Now walk thru each property in the schema
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$newPipeScriptParameters = [Ordered]@{}
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:nextProperty foreach ($property in $schemaDefinition.properties.psobject.properties) {
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# Filter out excluded properties
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if ($ExcludeProperty) {
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foreach ($exc in $ExcludeProperty) {
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if ($property.Name -like $exc) {
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continue nextProperty
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}
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}
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}
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# Filter included properties
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if ($IncludeProperty) {
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$included = foreach ($inc in $IncludeProperty) {
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if ($property.Name -like $inc) {
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$true;break
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}
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}
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if (-not $included) { continue nextProperty }
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}
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# Convert the property into a parameter name
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$parameterName = $property.Name | getSchemaParameterName
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# Collect the parameter attributes
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$parameterAttributes = @(
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# The description comes first, as inline help
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$propertyDescription = $property.value.description
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if ($propertyDescription -match '\n') {
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" <#"
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" " + $($propertyDescription -split '(?>\r\n|\n)' -join ([Environment]::NewLine + (' ' * 4))
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)
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" #>"
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} else {
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"# $propertyDescription"
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}
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"[Parameter($(
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if ($property.value.required -and -not $NoMandatory) { "Mandatory,"}
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)ValueFromPipelineByPropertyName)]"
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# Followed by the defaultBindingProperty (the name of the JSON property)
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"[ComponentModel.DefaultBindingProperty('$($property.Name)')]"
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# Keep track of if null was allowed and try to resolve the type
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$nullAllowed = $false
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$propertyTypeInfo =
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if ($property.value.'$ref') {
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# If there was a reference, try to resolve it
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$referencedType = $schemaObject | resolveSchemaDefinition $property.value.'$ref'
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if ($referencedType) {
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$referencedType
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}
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} else {
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# If there is not a oneOf, return the value
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if (-not $property.value.'oneOf') {
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$property.value
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} else {
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# If there is oneOf, see if it's an optional null
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$notNullOneOf =
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@(foreach ($oneOf in $property.value.oneOf) {
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if ($oneOf.type -eq 'null') {
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$nullAllowed = $true
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continue
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}
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$oneOf
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})
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if ($notNullOneOf.Count -eq 1) {
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$notNullOneOf = $notNullOneOf[0]
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if ($notNullOneOf.'$ref') {
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$referencedType = $schemaObject | resolveSchemaDefinition $notNullOneOf.'$ref'
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if ($referencedType) {
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$referencedType
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}
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} else {
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$notNullOneOf
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}
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} else {
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"[PSObject]"
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}
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}
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}
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# If there was a single type with an enum
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if ($propertyTypeInfo.enum) {
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$validSet = @() + $propertyTypeInfo.enum
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if ($nullAllowed) {
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$validSet += ''
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}
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# create a validateset.
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"[ValidateSet('$($validSet -join "','")')]"
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"[string]"
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}
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# If there was a validation pattern
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elseif ($propertyTypeInfo.pattern)
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{
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$validPattern = $propertyTypeInfo.pattern
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if ($nullAllowed) {
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$validPattern = "(?>^\s{0}$|$validPattern)"
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}
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$validPattern = $validPattern.Replace("'", "''")
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# declare a regex.
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"[ValidatePattern('$validPattern')]"
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}
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# If there was a property type
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if ($propertyTypeInfo.type) {
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# limit the input
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switch ($propertyTypeInfo.type) {
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"string" {
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"[string]"
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}
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"integer" {
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"[int]"
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}
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"number" {
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"[double]"
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}
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"boolean" {
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"[switch]"
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}
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"array" {
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"[PSObject[]]"
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}
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"object" {
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"[PSObject]"
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}
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}
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}
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)
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$parameterAttributes += "`$$parameterName"
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$newPipeScriptParameters[$parameterName] = $parameterAttributes
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}
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$newPipeScriptSplat.Parameter = $newPipeScriptParameters
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# If there was no scriptblock, or it was nothing but an empty param()
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if ($ScriptBlock -match '^[\s\r\n]{0,}(?:param\(\))?[\s\r\n]{0,1}$') {
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# Create a script that will create the schema object.
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$newPipeScriptSplat.Process = [scriptblock]::Create("
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`$schemaTypeName = '$("$schemauri".Replace("'","''"))'
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" + {
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# Get my script block
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$myScriptBlock = $MyInvocation.MyCommand.ScriptBlock
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# and declare an output object.
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$myParamCopy = [Ordered]@{PSTypeName=$schemaTypeName}
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# Walk over each parameter in my own AST.
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foreach ($param in $myScriptBlock.Ast.ParamBlock.Parameters) {
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# if there are not attributes, this parameter will not be mapped.
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if (-not $param.Attributes) {
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continue
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}
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# If the parameter was not passed, this parameter will not be mapped.
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$paramVariableName = $param.Name.VariablePath.ToString()
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if (-not $PSBoundParameters.ContainsKey($paramVariableName)) {
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continue
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}
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# Not walk over each attribute
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foreach ($attr in $param.Attributes) {
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# If the attribute is not a defaultbindingproperty attribute,
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if ($attr.TypeName.GetReflectionType() -ne [ComponentModel.DefaultBindingPropertyAttribute]) {
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continue # keep moving.
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}
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# Otherwise, update our object with the value
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$propName = $($attr.PositionalArguments.value)
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$myParamCopy[$propName] = $PSBoundParameters[$paramVariableName]
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# (don't forget to turn switches into booleans)
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if ($myParamCopy[$propName] -is [switch]) {
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$myParamCopy[$propName] = $myParamCopy[$propName] -as [bool]
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}
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}
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}
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# By converting our modified copy of parameters into an object
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# we should have an object that matches the schema.
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[PSCustomObject]$myParamCopy
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})
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}
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# If we are transpiling a script block
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if ($PSCmdlet.ParameterSetName -eq 'ScriptBlock') {
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# join the existing script with the schema information
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Join-PipeScript -ScriptBlock $ScriptBlock, (
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New-PipeScript @newPipeScriptSplat
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)
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}
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elseif ($PSCmdlet.ParameterSetName -eq 'Protocol')
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{
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# Otherwise, create a script block that produces the schema.
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[ScriptBlock]::create("{
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$(New-PipeScript @newPipeScriptSplat)
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}")
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}
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}

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