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POInstantiate a Class as an Iterable
 

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    <p>I have a Class that I'm instantiating and then passing into a Tornado Web template. Both functions return a list, but I'm missing something in making the Class itself an iterable object. I'm afraid it's something fundamental I'm doing incorrectly. I'm making REST API calls, parsing the returned XML and returning some of the data to the webapp. Here's the code:</p> <p>The API calls:</p> <pre><code>class GetVMList: def __init__(self): user = 'contoso\\administrator' password = "apassword" url = "http://scspf:8090/SC2012/VMM/Microsoft.Management.Odata.svc/VirtualMachines?$filter=VMMServer%20eq%20'scvmm'" passman = urllib2.HTTPPasswordMgrWithDefaultRealm() passman.add_password(None, url, user, password) # create the NTLM authentication handler auth_NTLM = HTTPNtlmAuthHandler.HTTPNtlmAuthHandler(passman) # create and install the opener opener = urllib2.build_opener(auth_NTLM) urllib2.install_opener(opener) # retrieve the result self.response = urllib2.urlopen(url) self.data = self.response.read() def name(self): dom = parseString(self.data) raw_xml = dom.getElementsByTagName('d:Name') clean_xml = [] clean_data = [] for i in raw_xml: clean_xml.append(i.toxml()) for i in clean_xml: clean_data.append(i.replace('&lt;d:Name&gt;', '').replace('&lt;/d:Name&gt;', '')) return clean_data def os(self): dom = parseString(self.data) raw_xml = dom.getElementsByTagName('d:OperatingSystem') clean_xml = [] clean_data = [] for i in raw_xml: clean_xml.append(i.toxml()) for i in clean_xml: clean_data.append(i.replace('&lt;d:OperatingSystem&gt;', '').replace('&lt;/d:OperatingSystem&gt;', '')) return clean_data </code></pre> <p>The instantiation:</p> <pre><code>class ListHandler(tornado.web.RequestHandler): def get(self): self.render('temp/search.html', data='') def post(self): vm_list = GetVMList() self.render('temp/search.html', data=vm_list) </code></pre> <p>And then the template contains this: </p> <pre><code>{% for vm in data %} &lt;li&gt;{{ vm.name }} running {{ vm.os }}&lt;/li&gt; {% end %} </code></pre> <p>The error is: <code>TypeError: iteration over non-sequence</code>. I would imagine I need to use <code>__iter__</code> in my Class, but I'm not sure I understand exactly how it works.</p>
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    1. USDanielscottt
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    1. COI don't see an `__iter__()` method, so of course the instances of the `GetVMList` class are not iterable. Also, you probably should not name the class `GetVMList()` but rather `VMList()` ... classes are nouns, not verbs. Finally, you probably really want an iterator/generator for this, not a class. And on top of that, a *list* of VMs would not have a `name` or `os`, those are attributes of the individual VMs, but you have provided no way of specifying *which* VM you want the name or OS of. You badly need to rethink your design.
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    2. COWhat should be returned? e.g. `for x in GetVMList(): print x` What should be printed?
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      1. USmgilson
    3. CO@kindall thanks so much, this is exactly the type of advice. This isn't something I know a lot about; your advice is really helpful. I figured `__iter__` was what I needed, but unsure on how to implement it.
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