String replacement in MongoDB?

Question

I have a collection that has a number of documents where the title contains encoded & characters (&) and I would like to convert these back.

I'm wondering if it is possible to do a string replacement on a value based on it's original value.

For example with the document below:

{
   title: "this &amp; that"
}

Is it possible to replace the & with a normal update statement? I tried something like this:

db.questions.update({title: /&amp;/}, {title: title.replace(/&amp;/g, "&")});

But it threw the following error: ReferenceError: title is not defined

Can it be done using an update statment? If not, is the best way just to do a find/foreach/update on each document?

BatScream · Accepted Answer · 2014-12-01 22:52:14Z

1

I'm wondering if it is possible to do a string replacement on a value based on it's original value....Can it be done using an update statment?

Currently, it is not possible to update a field's value in mongodb by accessing,modifying its original value in a single update statement.

But it threw the following error: ReferenceError: title is not defined

This error occurs, because Mongodb does not see the title field of the document that is getting updated in its scope.

If not, is the best way just to do a find/foreach/update on each document?

Yes. You need to do it that way.

db.collection.find({"title":/&amp/}).forEach(function(doc){
db.collection.update({"_id":doc._id},
                     {$set:{"title": doc.title.replace(/&amp;/g, "&")}})
})

answered Dec 1, 2014 at 22:52

BatScream

19.7k4 gold badges54 silver badges68 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

String replacement in MongoDB?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related