使用PyMongo将事物添加到MongoDB文档中

Question

Using MongoDB, I have a history collection, with multiple documents in it. When initiatied, they look like this :

{'_id': ObjectId('58a71211545fc61fd8b2f420'),
 'category': 'blue',
 'last_update': datetime.datetime(2017, 2, 14, 0, 1),
 'timeline': [
    {
    'score': 0,
    'when': datetime.datetime(2017, 2, 14, 0, 1)
    }
 ]
}

{'_id': ObjectId('58a71211545fc61fd8b2f421'),
 'category': 'red',
 'last_update': datetime.datetime(2017, 2, 14, 0, 1),
 'timeline': [
    {
    'score': 0,
    'when': datetime.datetime(2017, 2, 14,  0, 1)
    }
 ]
}

Using PyMongo, I would like a query that adds things into a document (for instance, for the document with {'category' : 'blue'} ), in the timeline element, like that :

{'_id': ObjectId('58a71211545fc61fd8b2f420'),
 'category': 'blue',
 'timeline': [
    {
    'score': 0,
    'when': datetime.datetime(2017, 2, 14, 0, 1)
    },
    {
    'score': 10,
    'when': datetime.datetime(2017, 2, 14, 0, 2)
    },
    {
    'score': 20,
    'when': datetime.datetime(2017, 2, 14, 0, 3)
    }
 ]
}

The only thing I found out (with collection.update_one() ) erases the previous content :

{'_id': ObjectId('58a71211545fc61fd8b2f420'),
 'category': 'blue',
 'timeline': [
    {
    'score': 10,
    'when': datetime.datetime(2017, 2, 14, 0, 2)
    },
    {
    'score': 20,
    'when': datetime.datetime(2017, 2, 14, 0, 3)
    }
 ]
}

Thanks

Answer 1

Use the update operator $push .

db.my_collection.update_one({'category': 'blue'}, {
    '$push': {'timeline': {'score': 30, 'when': datetime.datetime.now()}}}