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When using MongoDB , there are several ways to list the collections in the database. This article will discuss four different ways to get a list of collections in a MongoDB database.

These methods are as follows:

show collectionsList all collections in MongoDB Shell using command

You will use the Mongo shell command show collectionsto get a list of MongoDB collections. This command generates a list of all the collections you have created in your MongoDB database.

It would be best if you first select a database where at least one collection exists to use the command.

Let's use usethe command to select a database.

use <BlocTAKdatabase>

Afterwards, you can use show collectionsquery to run commands.

show collections

The result of the above query is shown below.

employees
clients
clienttype
services
system.views

In this case, there are five results. clienttypeis a view, although you can't tell by looking at it.

The remaining items are collections. system.viewsis a system collection that contains information about each database view.

Your access level will determine the output of the returned collection.

listCollectionsList all collections in MongoDB Shell using command

Administrator command listCollectionsReturns the names and options of all collections and views in the database. The generated data is in the form of documents.

Given below is the query for this command.

db.runCommand( { listCollections: 1, authorizedCollections: true, nameOnly: true } )

The result of the above query is given in the screenshot below.

This document contains information on creating a cursor for a collection of information. You can also run the command like this:

db.runCommand( { listCollections: 1.0 } )

Using this can provide a wealth of information about a collection. Check out the example below db.getCollectionInfos()to see the data returned when you run it like this.

db.getCollectionNames()List all collections in MongoDB Shell using method

The function db.getCollectionNames()returns an array containing the names of all collections and views in the current database. In addition, if access control is enabled, the names of the collections are based on the user's permissions.

The query for this method is given below.

db.getCollectionNames()

The result of the above query is shown below.

[ "employees", "clients", "clienttype", "services", "system.views" ]

db.getCollectionInfos()List all collections in MongoDB Shell using method

db.getCollectionInfos()The method generates an array of documents that contain information about the current set of database views, such as name and options. Again, it determines the results by the user's permission level.

Here you have a query that calls it without any parameters.

db.getCollectionInfos()

The result of the above query is given in the screenshot below.

db.getCollectionInfos()The real definition is as follows:

db.getCollectionInfos(filter, nameOnly, authorizedCollections)

Therefore, you can use filterthe parameter to narrow the collection list by a query phrase. You can use it on any field returned by the method.

nameOnlyThe parameter can specify that the method should return only the name of the collection.

nameOnly: trueWhen used with the , authorizedCollectionsparameter allows a user to run a command without the required permissions to apply access controls. In this case, the command returns only the collections that the user has access to.

Here is a query using with these parameters db.getCollectionInfos().

db.getCollectionInfos( {}, true, true )

The result of the above query is given in the screenshot below.

Here is an example of a query where you can filter it to a specific name.

db.getCollectionInfos( { name: "clients" }, true, true )

The result of the above query is shown below.

[ { "name" : "clients", "type" : "collection" } ]

This is what happens when you remove the last two parameters.

db.getCollectionInfos( { name: "clients" } )

The result of the above query is shown below.

[
    {
        "name" : "clients",
        "type" : "collection",
        "options" : {

        },
        "info" : {
            "readOnly" : false,
            "uuid" : UUID("91d1c6d8-8516-455d-a3c2-b157e1998f8c")
        },
        "idIndex" : {
            "v" : 2,
            "key" : {
                "_id" : 1
            },
            "name" : "_id_"
        }
    }
]

So, using this MongoDB article, you now have four different methods at your disposal to list all the collections present in a MongoDB database. These methods are show collectionsthe command, listCollectionscommand, db.getCollectionNames()method, and db.getCollectionInfos()method.