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see Getting Started with Amazon Web Services in China
(PDF).
$unset
New from version 8.0
Not supported by Elastic cluster.
The $unset aggregation stage in Amazon DocumentDB allows you to remove fields from documents.
Parameters
Example (MongoDB Shell)
The following example demonstrates the use of the $unset aggregation stage to remove the price field.
Create sample documents
db.inventory.insertMany([
{ item: "pencil", quantity: 100, price: 0.24},
{ item: "pen", quantity: 204, price: 1.78 }
]);
Aggregation example
db.inventory.aggregate([
{
$unset: "price"
}
])
Output
[
{
_id: ObjectId('69248951d66dcae121d2950d'),
item: 'pencil',
quantity: 100
},
{
_id: ObjectId('69248951d66dcae121d2950e'),
item: 'pen',
quantity: 204
}
]
Code examples
To view a code example for using the $unset command, choose the tab for the language that you want to use:
- Node.js
-
const { MongoClient } = require('mongodb');
async function example() {
const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
const db = client.db('test');
const inventory = db.collection('inventory');
const result = await inventory.aggregate([
{
$unset: "price"
}
]).toArray();
console.log(result);
client.close();
}
example();
- Python
-
from pymongo import MongoClient
def example():
client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
db = client['test']
inventory = db['inventory']
result = list(inventory.aggregate([
{
"$unset": "price"
}
]))
print(result)
client.close()
example()