Get-AzTemplateParameters.ps1

<#
  .SYNOPSIS
    Returns a hashtable of all parameters from the template file merged with the parameters object you provide
#>
function Get-AzTemplateParameters{
  param(
    [string]
    $ParametersFilePath,

    [hashtable]
    $TemplateParameterObject = @{}
  )

  if (!$ParametersFilePath) {
    return $TemplateParameterObject
  }

  $parameterFileJson = (Get-Content -Raw $ParametersFilePath | ConvertFrom-Json)
  $parameters = @{}
  $keys = ($parameterFileJson.parameters | get-member -MemberType NoteProperty | ForEach-Object {$_.Name})
  foreach ($key in $keys) {
    $parameters[$key] = $parameterFileJson.parameters.$key.value
  }
  foreach ($key in $TemplateParameterObject.Keys) {
    if ($parameters.ContainsKey($key)) {
      $parameters.Remove($key)
    }
  }

  return $parameters + $TemplateParameterObject
}