$set Sets the value of a field in a document. $setOnInsert Sets the value of a field if an update results in an insert of a document. Has no effect on update operations that modify existing documents. $unset Removes the specified field from a document. ← Update Operators$currentDate→...
With MongoDB version 4.2+, updates are more flexible as it allows the use of aggregation pipeline in its update, updateOne and updateMany. You can now transform your documents using the aggregation operators then update without the need to explicity state the $set command (instead we use $repl...
When using a field of type Hash, be wary of adhering to the legal key names for mongoDB, or else the values will not store properly. class Person include Mongoid::Document field :first_name field :url, type: Hash # will update the fields properly and save the values def set_vals sel...
Also note"$toString"which is a new aggregation operator introduced inMongo 4.0. In case your cast isn't from double to string, you have the choice between different conversion operators introduced inMongo 4.0such as$toBool,$toInt, ... And if there isn't a dedicated converter for your targ...
MongoDB Manual / Aggregation Operations / Aggregation Reference / Aggregation Operators$unsetField (aggregation)Definition $unsetField New in version 5.0. Removes a specified field in a document. You can use $unsetField to remove fields with names that contain periods (.) or that start wit...
BSONElement e = i.next();if( e.eoo() )break;stringname = e.embeddedObject().getField("name").valuestr();if( !e.embeddedObject().getBoolField("empty") ) {if( name !="local") {if( only.empty() || only == name ) {log(2) <<"adding to 'addDbNextPass': "<< name <<...
在MongoDB中,`$unset`操作符用于删除一个字段。在这个例子中,`{$unset:{field:1}}`表示删除名为`field`的字段。这里的`1`是一个占位符,表示要删除该字段。 在云...
The following operation uses the$matchpipeline stage to find a specific document and the$replaceWithpipeline stage and the$setFieldand$literaloperators to update the"$price"field in the matching document: db.inventory.aggregate([ {$match:{_id:1} }, ...
Update Operators: https://docs.mongodb.com/manual/reference/operator/update-field/ Update One:https://docs.mongodb.com/manual/reference/method/db.collection.updateOne/ Replace One: https://docs.mongodb.com/manual/reference/method/db.collection.replaceOne/ Share Improve this answer Follow answered...
Update: I revisited this project recently, and rewrote the DB layer to use a SQL database, and everything was much easier. A complex processing pipeline is now a simpleSELECT DISTINCT(colName) WHERE xxxoperation. Realistically, MongoDB and NoSQL databases in general are vary much the wrong ...