Replace a word from a string - mongodb

Question

I have mongodb documents with a field like this:
Image : http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-zoom.jpg
How can I replace the zoom part in the string value with some other text in order to get:
Image : http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-product2.jpg

Answer 1

You could use mongo's forEach() cursor method to do an atomic update with the $set operator :
db.collection.find({}).snapshot().forEach(function(doc) {
var updated_url = doc.Image.replace('zoom', 'product2');
db.collection.update(
{"_id": doc._id},
{ "$set": { "Image": updated_url } }
);
});
Given a very large collection to update, you could speed up things a little bit with bulkWrite and restructure your update operations to be sent in bulk as:
var ops = [];
db.collection.find({}).snapshot().forEach(function(doc) {
ops.push({
"updateOne": {
"filter": { "_id": doc._id },
"update": { "$set": { "Image": doc.Image.replace('zoom', 'product2') } }
}
});
if ( ops.length === 500 ) {
db.collection.bulkWrite(ops);
ops = [];
}
})
if ( ops.length > 0 )
db.collection.bulkWrite(ops);

Answer 2

db.myCollection.update({image: 'http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-zoom.jpg'}, {$set: {image : 'http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-product2.jpg'}})
If you need to do this multiple times to multiple documents, you need to iterate them with a function. See here: MongoDB: Updating documents using data from the same document

Answer 3

Nowadays,
starting Mongo 4.2, db.collection.updateMany (alias of db.collection.update) can accept an aggregation pipeline, finally allowing the update of a field based on its own value.
starting Mongo 4.4, the new aggregation operator $replaceOne makes it very easy to replace part of a string.
// { "Image" : "http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-zoom.jpg" }
// { "Image" : "http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-boom.jpg" }
db.collection.updateMany(
{ "Image": { $regex: /zoom/ } },
[{
$set: { "Image": {
$replaceOne: { input: "$Image", find: "zoom", replacement: "product2" }
}}
}]
)
// { "Image" : "http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-product2.jpg" }
// { "Image" : "http://static14.com/p/Inc.5-Black-Sandals-5131-2713231-7-boom.jpg" }
The first part ({ "Image": { $regex: /zoom/ } }) is just there to make the query faster by filtering which documents to update (the ones containing "zoom")
The second part ($set: { "Image": {...) is the update aggregation pipeline (note the squared brackets signifying the use of an aggregation pipeline):
$set is a new aggregation operator (Mongo 4.2) which in this case replaces the value of a field.
The new value is computed with the new $replaceOne operator. Note how Image is modified directly based on the its own value ($Image).