MongoDB: How to update multiple documents with a single command?

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I was surprised to find that the following example code only updates a single document:

> db.test.save({"_id":1, "foo":"bar"});
> db.test.save({"_id":2, "foo":"bar"});

> db.test.update({"foo":"bar"}, {"$set":{"test":"success!"}});

> db.test.find({"test":"success!"}).count();
1

I know I can loop through and keep updating until they're all changed, but that seems terribly inefficient. Is there a better way?

13 Answers

To Update Entire Collection,

db.getCollection('collection_name').update({},
{$set: {"field1" : "value1", "field2" : "value2", "field3" : "value3"}},
{multi: true })

The following command can update multiple records of a collection

db.collection.update({}, 
{$set:{"field" : "value"}}, 
{ multi: true, upsert: false}
)

The updateMany() method has the following form:

db.collection.updateMany(
   <filter>,
   <update>,
   {
     upsert: <boolean>,
     writeConcern: <document>,
     collation: <document>,
     arrayFilters: [ <filterdocument1>, ... ],
     hint:  <document|string>        // Available starting in MongoDB 4.2.1
   }
)

The restaurant collection contains the following documents:

{ "_id" : 1, "name" : "Central Perk Cafe", "violations" : 3 }
{ "_id" : 2, "name" : "Rock A Feller Bar and Grill", "violations" : 2 }
{ "_id" : 3, "name" : "Empire State Sub", "violations" : 5 }
{ "_id" : 4, "name" : "Pizza Rat's Pizzaria", "violations" : 8 }

The following operation updates all documents where violations are greater than 4 and $set a flag for review:

try {
   db.restaurant.updateMany(
      { violations: { $gt: 4 } },
      { $set: { "Review" : true } }
   );
} catch (e) {
   print(e);
}
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