MongoDB Node.js to Replace String in Document
Today this article will see how to write a query using MongoDB Node.js to replace string or substring In a Document
We will replace a string in the Mongo document with the input string using a simple and easy approach i.e using $replaceOne aggregation operator which is supported in MongoDB v4.0 onwards.
We will cover below aspects,
We already looked at a simple way of adding or updating a new field to the document in our previous MongoDB sample series.
Getting started -MongoDB Node.js to Replace String
Here below is a sample schema or document we shall use,
Node.js – Replace Substring in MongoDB using replaceOne Aggregator
We are going to use a newly introduced aggregate operator to replace easily a string with matching criteria with part of the string.
What is $replaceOne
$replaceOne is aggregation operator which helps replace the first instance of a search string in an input string with a replacement string.
This operator usage is case-sensitive.
Query Pattern Replace using $replaceOne
{
$replaceOne: {
input: <expression>,
find: <expression>,
replacement: <expression>}
}
In the above query,
| input | Input string with search criteria. |
| find | Find the document with matching input string criteria. |
| replacement | The string to use to replace the first matched instance from input |
You can replace the existing Mongo field using any other fields from the document using the above approach + using the approach discussed here.
Node.js Example using $replaceOne
In the below example, we will replace “total-order” with “order” in the mongo field.
Please add below using namespace
import { MongoClient } from 'mongodb';
Define the Regex query for the matching string,
'Link': {
'$regex': new RegExp('total-order')
}
Define the Set using replaceOne Operator,
'$set': {
'Link': {
'$replaceOne': {
'input': '$Link',
'find': 'total-order',
'replacement': 'order'
}
}
}
Example
const filter = {
'Link': {
'$regex': new RegExp('total-order')
}
},[
{
'$set': {
'Link': {
'$replaceOne': {
'input': '$Link',
'find': 'total-order',
'replacement': 'order'
}
}
}
}
];
const client = await MongoClient.connect(
'mongodb://host/',
{ useNewUrlParser: true, useUnifiedTopology: true }
);
const coll = client.db('TheCodeBuzz').collection('Orders');
const cursor = coll.find(filter);
const result = await cursor.toArray();
await client.close();Below is the schema post-update,
That’s all! Happy coding!
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