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POHow can I determine a user_id based on an email address in App Engine?
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  1. POHow can I determine a user_id based on an email address in App Engine?
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    copied!<p>The newest App Engine SDK (1.2.1) has an API call to compute an ID for a user account based on his email address. (The ID remains the same even if the user changes his address later.) See this <a href="https://stackoverflow.com/questions/778965/generating-unique-and-opaque-user-ids-in-google-app-engine">question about unique, opaque user IDs</a> for information. However, I have a problem with this API call.</p> <p><code>user_id()</code> works for logged-in users (i.e. from <code>users.get_current_user)</code>, but it returns <code>None</code> for objects created by the <code>users.User()</code> constructor.** What gives?</p> <p>For example, using the excellent <a href="http://con.appspot.com" rel="nofollow noreferrer">App Engine Console</a>, this code <strong>does not work</strong>.</p> <pre><code>&gt;&gt;&gt; import google.appengine.api.users &gt;&gt;&gt; me = google.appengine.api.users.get_current_user() &gt;&gt;&gt; me users.User(email='jason.h.smith@gmail.com',_user_id='105261964646342707921') &gt;&gt;&gt; me.user_id() '105261964646342707921' &gt;&gt;&gt; somebody = google.appengine.api.users.User('someone@gmail.com') &gt;&gt;&gt; somebody users.User(email='someone@gmail.com') &gt;&gt;&gt;somebody.user_id() &gt;&gt;&gt; type(somebody.user_id()) &lt;type 'NoneType'&gt; </code></pre> <p>I want a simple way to convert an email address to a user ID. <em>How can I coerce this ID from Google ahead of time; or if it's not possible, why not?</em></p> <h2>Edit: Here is the current workaround.</h2> <p>Thanks to Nick Johnson for his answer. Here is his solution in action:</p> <pre><code>&gt;&gt;&gt; from google.appengine.ext import db &gt;&gt;&gt; from google.appengine.api import users &gt;&gt;&gt; class User(db.Model): ... user = db.UserProperty(required=True) ... &gt;&gt;&gt; def email_to_userid(address): ... """Return a stable user_id string based on an email address, or None if ... the address is not a valid/existing google account.""" ... u = users.User(address) ... key = User(user=u).put() ... obj = User.get(key) ... return obj.user.user_id() &gt;&gt;&gt; email_to_userid('jason.h.smith@gmail.com') u'105261964646342707921' &gt;&gt;&gt; email_to_userid('this@is-an-invalid-email-address') &gt;&gt;&gt; email_to_userid('this@is-an-invalid-email-address') is None True </code></pre>
 

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