title: SOAP syntax in Powershell 3.0
body: <p>I'm trying to use Magento's SOAP v2 API (Magento Enterprise, ver 1.12.0.2) to interact with products and their attributes, but our store has a lot of custom attributes to edit. Aside from the default name, description, price, etc., we have additional attributes that I'm having trouble accessing via SOAP v2. I tried using the catalogProductUpdate method to edit attributes (<a href="http://devdocs.magento.com/guides/m1x/api/soap/catalog/catalogProduct/catalog_product.update.html" rel="nofollow">devdocs page here</a>), but I couldn't understand how to properly set up the "additional_attributes" field to allow editing of custom attributes. I keep getting back an error saying it's not in the correct format. For example, we have music products, so we want to set a value for our "artist" field.</p>
  
  <p>WS-I compliance is not enabled in our Magento.</p>
  
  <p>I'm in Powershell 3.0 using new-webserviceproxy, so I believe that means I'm using .NET framework. So my attempt looks something like this</p>
  
  <pre><code>$proxy = new-webserviceproxy -uri $soapuri
  
  $sessionid = $proxy.login($username,$password)
  
  $array1 = @{"key"="artist";"value"="4845"} #I also tried setting the value to the name instead of the ID number (ie. "key" = "artist";"value"="Billy Joel") but that returned the same error.
  
  $array2 = @{"single_data" = $array1}
  
  $proxy.catalogproductupdate($sessionid, &lt;a sku number&gt;, "admin", @{"additional_attributes" = $array2}, "sku")
  </code></pre>
  
  <p>But what returns is an error message saying that the attribute update was not expecting a "system.collections.hashtable". I believe I just have the formatting incorrect regarding the single-data/multi_data nesting. From how I understand it, the additional_attributes parameter's array requires the "single_data" parameter inside it, and inside "single_data" should be the actual attribute listings and values. So altogether it's like a 3-teir hash table.</p>
  
  <p>I am able to use hash table formatting to edit other, non-custom attributes, so I know the problem is not the hash table itself. It's just the "additional_attributes" field.</p>
  
  <p>Thanks for any assistance.</p>