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$toString
New from version 4.0
The $toString operator in Amazon DocumentDB is used to convert a value of any type (except for null) to a string representation. This can be useful when you need to perform string operations on values that are not originally in string format.
Parameters
Example (MongoDB Shell)
The following example demonstrates how to use the $toString operator to convert numeric values to strings.
Create sample documents
db.numbers.insertMany([
{ "_id": 1, "value": 42 },
{ "_id": 2, "value": 3.14 }
]);
Query example
db.numbers.aggregate([
{ $project: {
_id: 1,
valueAsString: { $toString: "$value" }
}}
]);
Output
{ "_id": 1, "valueAsString": "42" }
{ "_id": 2, "valueAsString": "3.14" }
Code examples
To view a code example for using the $toString 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 collection = db.collection('numbers');
const result = await collection.aggregate([
{ $project: {
_id: 1,
valueAsString: { $toString: '$value' }
}}
]).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']
collection = db['numbers']
result = list(collection.aggregate([
{ '$project': {
'_id': 1,
'valueAsString': { '$toString': '$value' }
}}
]))
print(result)
client.close()
example()