remove

Remove one or multiple documents from MongoDB collection

Since R2021b

Syntax

n = remove(conn,collection,mongoquery)

Description

n = remove(conn,collection,mongoquery) returns the number of documents removed from a collection using the MongoDB^® C++ interface connection. Use a MongoDB query to specify removing one or multiple documents.

Examples

Remove Documents Using MongoDB Query

Connect to MongoDB® using the MongoDB C++ interface and remove documents from a collection. Specify a MongoDB query to determine which documents to remove. In this example, the collection represents employee data.

Create a MongoDB connection to the database mongotest using the MongoDB C++ interface. Here, the database server dbtb01 hosts this database using port number 27017.

server = "dbtb01";
port = 27017;
dbname = "mongotest";
conn = mongoc(server,port,dbname)

conn = connection with properties:
           Database: "mongotest"
           UserName: ""
             Server: "dbtb01"
               Port: 27017
    CollectionNames: [14×1 string]

conn is the connection object that contains the MongoDB connection. The object properties contain information about the connection and the database.

• The database name is mongotest.

• The user name is blank.

• The database server is dbtb01.

• The port number is 27017.

• This database contains 14 document collections.

Verify the MongoDB connection.

isopen(conn)

ans = logical
   1

The database connection is successful because the isopen function returns 1. Otherwise, the database connection is closed.

Create a MongoDB query to identify documents to remove. For this example, specify the employeedata collection. Create the MongoDB query to identify documents in the department that has the department identifier set to 80.

collection = "employeedata";
mongoquery = "{""department_id"":80}";

Remove documents using the MongoDB query. The remove function removes three documents from the collection.

n = remove(conn,collection,mongoquery)

n = int64
    3

Close the MongoDB connection.

close(conn)

Remove All Documents from Collection

Connect to MongoDB® using the MongoDB C++ interface and remove all documents from a collection. In this example, the collection represents employee data.

Create a MongoDB connection to the database mongotest using the MongoDB C++ interface. Here, the database server dbtb01 hosts this database using port number 27017.

server = "dbtb01";
port = 27017;
dbname = "mongotest";
conn = mongoc(server,port,dbname)

conn = connection with properties:
           Database: "mongotest"
           UserName: ""
             Server: "dbtb01"
               Port: 27017
    CollectionNames: [14×1 string]

conn is the connection object that contains the MongoDB connection. The object properties contain information about the connection and the database.

• The database name is mongotest.

• The user name is blank.

• The database server is dbtb01.

• The port number is 27017.

• This database contains 14 document collections.

Verify the MongoDB connection.

isopen(conn)

ans = logical
   1

The database connection is successful because the isopen function returns 1. Otherwise, the database connection is closed.

Remove all documents from the employeedata collection. Use an empty MongoDB query to specify removing all documents. The remove function removes three documents from the collection.

collection = "employeedata";
n = remove(conn,collection,"{}")

n = int64
    3

Close the MongoDB connection.

close(conn)

Input Arguments

conn — MongoDB C++ interface connection

connection object

MongoDB C++ interface connection, specified as a connection object.

collection — Collection name

string scalar

Collection name, specified as a string scalar.

Example: "taxidata"

Data Types: string

mongoquery — MongoDB query

string scalar | character vector

MongoDB query, specified as a string scalar or character vector. Specify a JSON-style string to query the database.

Example: "{""department"":""Sales""}" queries the database for documents where the department field is equal to Sales.

Example: "{""salary"": {""$gt"": 90000}}" queries the database for documents where the value of the salary field is greater than 90000.

Data Types: string | char

Output Arguments

n — Number of documents removed

numeric scalar

Number of documents removed from a collection in the database, returned as a numeric scalar.

Version History

Introduced in R2021b