mirror of https://github.com/pallets/flask.git
104 lines
2.8 KiB
ReStructuredText
104 lines
2.8 KiB
ReStructuredText
MongoDB with MongoEngine
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========================
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Using a document database like MongoDB is a common alternative to
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relational SQL databases. This pattern shows how to use
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`MongoEngine`_, a document mapper library, to integrate with MongoDB.
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A running MongoDB server and `Flask-MongoEngine`_ are required. ::
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pip install flask-mongoengine
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.. _MongoEngine: http://mongoengine.org
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.. _Flask-MongoEngine: https://flask-mongoengine.readthedocs.io
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Configuration
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-------------
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Basic setup can be done by defining ``MONGODB_SETTINGS`` on
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``app.config`` and creating a ``MongoEngine`` instance. ::
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from flask import Flask
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from flask_mongoengine import MongoEngine
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app = Flask(__name__)
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app.config['MONGODB_SETTINGS'] = {
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"db": "myapp",
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}
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db = MongoEngine(app)
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Mapping Documents
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-----------------
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To declare a model that represents a Mongo document, create a class that
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inherits from ``Document`` and declare each of the fields. ::
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import mongoengine as me
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class Movie(me.Document):
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title = me.StringField(required=True)
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year = me.IntField()
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rated = me.StringField()
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director = me.StringField()
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actors = me.ListField()
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If the document has nested fields, use ``EmbeddedDocument`` to
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defined the fields of the embedded document and
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``EmbeddedDocumentField`` to declare it on the parent document. ::
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class Imdb(me.EmbeddedDocument):
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imdb_id = me.StringField()
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rating = me.DecimalField()
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votes = me.IntField()
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class Movie(me.Document):
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...
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imdb = me.EmbeddedDocumentField(Imdb)
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Creating Data
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-------------
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Instantiate your document class with keyword arguments for the fields.
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You can also assign values to the field attributes after instantiation.
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Then call ``doc.save()``. ::
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bttf = Movie(title="Back To The Future", year=1985)
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bttf.actors = [
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"Michael J. Fox",
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"Christopher Lloyd"
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]
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bttf.imdb = Imdb(imdb_id="tt0088763", rating=8.5)
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bttf.save()
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Queries
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-------
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Use the class ``objects`` attribute to make queries. A keyword argument
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looks for an equal value on the field. ::
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bttf = Movies.objects(title="Back To The Future").get_or_404()
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Query operators may be used by concatenating them with the field name
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using a double-underscore. ``objects``, and queries returned by
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calling it, are iterable. ::
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some_theron_movie = Movie.objects(actors__in=["Charlize Theron"]).first()
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for recents in Movie.objects(year__gte=2017):
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print(recents.title)
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Documentation
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-------------
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There are many more ways to define and query documents with MongoEngine.
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For more information, check out the `official documentation
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<MongoEngine_>`_.
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Flask-MongoEngine adds helpful utilities on top of MongoEngine. Check
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out their `documentation <Flask-MongoEngine_>`_ as well.
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