MongoDB: Find and replace string

help
1

I am trying to find an effective way for searching and replacing a string across a whole collection. Background is to replace all base URLs contained in a specific field with a new base URL.

According to the MongoDB NodeDriver docs, this should be possible with updateMany():

const rawCollection = myCollection.rawCollection();
rawCollection.updateMany({}, [
      {
        $set: {
          url: { $replaceOne: { input: '$url', find: oldUrl, replacement: newUrl } }
        }
      }
    ]);

However, the driver complains that it doesn’t understand $replaceOne. What is the correct way to do it in Meteor?

I know I could use a bulk operation and iterate over the collection manually, but I’d like to avoid this.

2

As far as I know $replaceOne is a pipeline operator to be used in aggregations only, and can’t be used in Collection.update.

3

According to the docs, it should be possible since 4.4, if you use the MongoDB driver (rawCollection) directly and call updateMany. This method supports passing in an aggregation pipeline.

1 Like
4

Just realized that my Meteor version 1.10.2 did not support MongoDB 4.4 yet, so that’s the reason why it’s not working in my dev environment. Thanks @peterfkruger for pointing me to this!

Still wondering if there’s another way to do collection-wide text replacements in MongoDB?

2 Likes
5

$split the string by the old url and $concat with the new url

6

Sounds interesting. How does this actually work? I could only see $split as part of the aggregation pipeline docs, but this would only work if my server was on a more recent Meteor version where updateMany supports aggregations (MongoDB 4.4+). And for this version, I could also use replaceOne. Maybe I missed something?

7

updateMany aggregation is available starting 4.2