如何将mongodb文档中的所有数组元素更改为某个值？

最好的方法是匹配数组元素，并

$

Bulk()

qty

var bulk = db.mycollection.initializeOrderedBulkOp(),       count = 0;db.mycollection.find({ "pre" : "efg" }).forEach(function(doc){     var qty = doc["qty"];     for (var idx = 0; idx < qty.length; idx++){         bulk.find({  "_id": doc._id,  "qty": { "$elemMatch": { "num": qty[idx]["num"]}}        }).update({ "$set": { "qty.$.num": 0 }})    }         count++;      if (count % 200 == 0) {         // Execute per 200 operations and re-init.        bulk.execute();         bulk = db.mycollection.initializeOrderedBulkOp();     } })// Clean up queuesif (count % 200 != 0)    bulk.execute();