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EJSON

EJSON.parse()

On this page

  • Syntax
  • Command Fields
  • Behavior
  • Examples
  • Format Input with EJSON.parse()
  • Use EJSON.parse() from the command line
  • Learn More

The EJSON.parse() method converts string values to JSON.

Syntax

The EJSON.parse() method takes a string as input and an optional modifier that controls the output format.

EJSON.parse(string, [options])

Command Fields

The EJSON.parse() method takes these fields:

Field
Type
Necessity
Description

value

string

Required

String EJSON.parse() transforms into JSON key-value pairs

options

string

Optional

Modifies output types. The only option is { relaxed: <boolean> }.

Value
Effect

true

Returns native JavaScript types when possible

false

Prefer to return BSON types

Behavior

You can call EJSON.parse() from inside an interactive mongosh session or from the system command line using --eval.

Call EJSON.parse() from an interactive session:

EJSON.parse(string)

Call EJSON.parse() from the system command line:

mongosh --eval "EJSON.parse(string)"

Examples

To try these examples, first 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"), },
] )

Format Input with EJSON.parse()

EJSON.parse() accepts a string as input. For this example, use the EJSON.stringify() method to export the sales collection as a string.

let salesCollection = EJSON.stringify( db.sales.find().toArray() )

Use EJSON.parse() to format the string for methods like db.collection.insertMany() that expect JSON pairs:

db.salesRestored.insertMany( EJSON.parse( salesCollection ) )

  • EJSON.parse() formats the values in salesCollection as JSON pairs.

  • db.salesRestored.insertMany() uses the JSON pairs to create the salesRestored collection.

Use EJSON.parse() from the command line

To import string data from an external source such as a file or an API call, use EJSON.parse() with the mongosh --eval method.

For this example, save the sales collection as a file.

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

The code creates a file on your local system called sales.json. To import the file and create a new collection, exit mongosh and run an --eval operation from the command line.

# Note: This example is formatted to fit on the page.
mongosh --quiet \
        --eval "db.salesFromFile.insertMany( \
           EJSON.parse( fs.readFileSync( 'sales.json', 'utf8' ) ) )"

  • EJSON.parse() takes a string as input. This example uses fs.readFileSync() to read the sale.json file as a string.

  • EJSON.parse() formats the input string as JSON pairs.

  • db.salesFromFile.insertMany() creates the salesFromFile collection from the JSON pairs.

Learn More

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deserialize()

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serialize()