Navigation

cursor.comment()

On this page

Definition

cursor.comment()

mongo Shell Method

This page documents the mongo shell method, and does not refer to the MongoDB Node.js driver (or any other driver) method. For corresponding MongoDB driver API, refer to your specific MongoDB driver documentation instead.

New in version 3.2.

Adds a comment field to the query.

cursor.comment() has the following syntax:

copy 
cursor.comment( <string> )

comment() has the following parameter:

Parameter Type Description
comment string The comment to apply to the query.

Behavior

comment() associates a comment string with the find operation. This can make it easier to track a particular query in the following diagnostic outputs:

See configure log verbosity for the mongod log, the Database Profiler tutorial, or the db.currentOp() command.

Example

The following operation attaches a comment to a query on the restaurants collection:

copy 
db.restaurants.find(
   { "borough" : "Manhattan" }
).comment( "Find all Manhattan restaurants" )

Output Examples

system.profile

The following is an excerpt from the system.profile:

copy 
{
   "op" : "query",
   "ns" : "guidebook.restaurant",
   "query" : {
      "find" : "restaurant",
      "filter" : {
         "borough" : "Manhattan"
      },
      "comment" : "Find all Manhattan restaurants"
   },
   ...
}

mongod log

The following is an excerpt from the mongod log. It has been formatted for readability.

Important

The verbosity level for QUERY must be greater than 0. See Configure Log Verbosity Levels

copy 
2015-11-23T13:09:16.202-05:00 I COMMAND  [conn1]
   command guidebook.restaurant command: find {
      find: "restaurant",
      filter: { "borough" : "Manhattan" },
      comment: "Find all Manhattan restaurants"
   }
   ...

db.currentOp()

Suppose the following operation is currently running on a mongod instance:

copy 
db.restaurants.find(
   { "borough" : "Manhattan" }
).comment("Find all Manhattan restaurants")

Running the db.currentOp() command returns the following:

copy 
{
   "inprog" : [
      {
         "host" : "198.51.100.1:27017",
         "desc" : "conn3",
         "connectionId" : 3,
         ...

         "op" : "query",
         "ns" : "test.$cmd",
         "command" : {
            "find" : "restaurants",
            "filter" : {
               "borough" : "Manhattan"
            },
            "comment" : "Find all Manhattan restaurants",
            "$db" : "test"
         },
         "numYields" : 0,
         ...
      }
   ],
   "ok" : 1
}

© MongoDB, Inc 2008-present. MongoDB, Mongo, and the leaf logo are registered trademarks of MongoDB, Inc.