CODEWITHSUNDEEP
mongodb
Daryl
Daryl

Reputation: 117

MongoDB is not updating all records, even with multi set to true

I have a collection representing Wikipedia pages, with title, categories and links, as represented below.

{
    "_id" : NumberLong(1975),
    "Categories" : [ 
        "pacific ocean"
    ],
    "Links" : [ 
        "volcano", 
        "trench", 
        "water", 
        ...
        "kilometer", 
        "plate tectonics", 
        "el niño"
    ],
    "Title" : "pacific ocean"
}

I need to update some values in the Links array, to do this, I'm doing the following.

db.WikipediaArticles.update({Links:"kilometer"}, {$set: {"Links.$": "kilometre"}}, {upsert:false, multi:true})

This, however, is not updating all documents (as expected) and I end up having to run it 3-4 times to have all records updated. Is there anyway I can guarantee that all documents are updated?

Upvotes: 1

Views: 280

Answers (1)

JohnnyHK
JohnnyHK

Reputation: 311865

$ identifies the index of the first matching element in the query, so each time you run the update it will only modify at most one Links element per doc.

Because Links can contain multiple elements of "kilometer", you need to keep running the update command until it reports that no docs were affected.

Upvotes: 3

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