update

Update one or multiple documents in MongoDB collection

Since R2021b

Syntax

n = update(conn,collection,findquery,updatequery)

Description

n = update(conn,collection,findquery,updatequery) returns the number of documents updated in a collection using the MongoDB^® C++ interface connection. Use MongoDB queries to find and update documents.

Examples

Update Documents in Collection

Connect to MongoDB® using the MongoDB C++ interface and update documents in a collection. Find documents to update by using a MongoDB query. Specify the criteria for the update by using a MongoDB query. 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: [13×1 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 13 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.

Specify the employees collection. Create a MongoDB query to find employees in the department where the department identifier is set to 90. Then, create a MongoDB query to increase the value in the salary field by 5000.

collection = "employees";
findquery = "{""department_id"":90}";
updatequery = "{""$inc"":{""salary"":5000}}";

Increase the salaries for all employees in the department using the MongoDB connection. The update function updates four documents in the collection.

n = update(conn,collection,findquery,updatequery)

n = int64
    4

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

findquery — MongoDB find query

string scalar | character vector

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

Example: "{""department"":""Sales""}" finds all documents where the department field is equal to Sales.

Example: "{""_id"":{""$oid"":""593fec95b78dc311e01e9204""}}" finds the document that has the identifier 593fec95b78dc311e01e9204.

Data Types: char | string

updatequery — MongoDB update query

string scalar | character vector

MongoDB update query, specified as a string scalar or character vector. Use a JSON-style string to specify the criteria for the update.

Example: "{""$inc"":{""salary"":5000}}" increases the values in the salary field by 5000.

Data Types: char | string

Output Arguments

n — Number of documents updated

numeric scalar

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

Version History

Introduced in R2021b