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POHow can I create a MongoEngine document with referenced documents that are already in the database?
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copied!<p>I already have a class of documents stored in my (Flask-MongoEngine) database, and <strong>I already have their unique id</strong>. My actual example is more complicated, but let's say it looks like this:</p> <pre><code>class Stuff(Document): stuffstuff = StringField() </code></pre> <p>I'd like to make a collection of Stuff instances from Stuffs already in my database. Let's say I want to make a new instance of the class below from Stuff instances currently in my database.</p> <pre><code>class StuffsCollection(Document): lotsofstuffs = ListField(ReferenceField(Stuff)) </code></pre> <p>In the <a href="http://docs.mongoengine.org/en/latest/tutorial.html?highlight=referencefield" rel="nofollow">ReferenceField</a> documentation, it looks like the only way to create a StuffsCollection instance is to first create instances of Stuff, then pass them in as keyword arguments. For example:</p> <pre><code>a_thing = Stuff(stuffstuff="here's a thing") a_thing.save() some_things = StuffsCollection(lotsofstuffs=[a_thing]) some_things.save() </code></pre> <p><strong>Since I already have the unique ids that reference my Stuff instances, can I just tell MongoEngine to use those existing Stuffs as keyword arguments in a new StuffsCollection?</strong> It seems like this would be more efficient than querying the database for each document, then creating a new instance of that document, then passing each into my new ListField.</p>

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