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EJSON.deserialize()

The EJSON.deserialize() method converts Extended JSON objects to BSON objects.

Syntax

The method has this syntax:

EJSON.deserialize( object, [ options ] )

Method Fields

The method takes the following fields:

Field	Type	Necessity	Description
`object`	EJSON object	Required	EJSON object to convert. For example, an array of documents.
`options`	string	Optional	Modifies the output object types. The only option is `{ relaxed: <boolean> }`. `true`: Return plain JavaScript object types. Default is `true`. `false`: Return BSON object types.

Behavior

You can run EJSON.deserialize() from an interactive mongosh session or from the system command line using --eval.

To run EJSON.deserialize() from an interactive mongosh session, use:

EJSON.deserialize( object, [ options ] )

To run EJSON.deserialize() from the system command line, use:

mongosh --eval "EJSON.deserialize( object, [ options ] )"

Example

Create the sales collection:

db.sales.insertMany( [
   { custId: 345, purchaseDate: ISODate("2023-07-04"),
     quantity: 4, cost: Decimal128("100.60") },
   { custId: 346, purchaseDate: ISODate("2023-07-12"),
     quantity: 3, cost: Decimal128("175.45") },
   { custId: 486, purchaseDate: ISODate("2023-08-01"),
     quantity: 9, cost: Decimal128("200.53") }
] )

The following sections show how to create an example file and then import the file with an EJSON.deserialize() example.

Create the Example File

The following example retrieves the sales documents as an array and saves the results to a file named salesDeserialize.json on the computer's file system:

let salesCollection = EJSON.stringify( db.sales.find().toArray() )
fs.writeFileSync( 'salesDeserialize.json', salesCollection )

Import the Example File from the Command Line

To import the salesDeserialize.json file and create a new collection named salesFromDeserializeFile, exit mongosh and then run this example from the command line:

# Note: The example is formatted to fit the page.
mongosh --quiet  --eval "db.salesFromDeserializeFile.insertMany( \
   EJSON.deserialize( JSON.parse ( \
   fs.readFileSync( 'salesDeserialize.json', 'utf8' ) ) ) )"

In the example:

fs.readFileSync() reads the salesDeserialize.json file and interprets the content as utf8 Unicode character strings.
JSON.parse() converts the strings read from the file to JSON.
EJSON.deserialize() outputs JSON.
db.salesFromDeserializeFile.insertMany() creates and populates the salesFromDeserializeFile collection using the JSON returned by EJSON.deserialize().

Note

You could use EJSON.parse() in the previous example, which is a simpler approach. JSON.parse() and EJSON.deserialize() provide more flexibility.

Warning

Validate Untrusted Input Before Converting JSON to BSON

If you convert a JSON string to BSON and use the resulting BSON in a query, update, or command, an attacker can inject operators or unexpected field values that change the meaning of the operation. This risk is greatest when the JSON originates from a user, an API request, or another untrusted source.

To learn more about validating input before conversion, see Validate Untrusted Input Before Converting JSON to BSON.

Learn More

EJSON deserialize method
EJSON documentation

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