JSON.GET

The JSON.GET command allows you to store, update, and retrieve JSON values in DiceDB. The JSON.GET command retrieves JSON data stored at a specified key. This command is useful for fetching JSON objects, arrays, or values from the DiceDB database.

Syntax

JSON.GET <key> [path]

Parameters

Parameter	Description	Type	Required
key	The key against which the JSON data is stored in DiceDB	String	Yes
path	A JSONPath expression to specify the part of the JSON document to retrieve. If not provided, the entire JSON document is returned. Default value is $ (root)	String	No

Return Values

Condition	Return Value
The specified key does not exists	nil
The specified key exists and path argument is not specified	String: The entire JSON data for the key
The specified key exists and the specified path exists in the JSON data	String: The data for the key at the specified path
The specified key exists and specified path does not exists in the JSON data	error
Syntax or specified constraints are invalid	error

Behaviour

When the JSON.GET command is executed:

1. DiceDB checks if the specified key exists.
2. If the key exists, DiceDB retrieves the JSON data stored at that key.
3. If a path is provided, DiceDB extracts the specified part of the JSON document using the JSONPath expression.
4. The retrieved JSON data is returned as a JSON string.

Errors

1. Incorrect number of arguments
   • Error Message: (error) ERR wrong number of arguments for 'json.get' command
2. Invalid JSONPath expression
   • Error Message: (error) ERR invalid JSONPath
3. Non-Existent JSONPath in the JSON data stored against a key
   • Error Message: (error) ERR Path '$.<path>' does not exist

Example Usage

Retrieve Entire JSON Document

127.0.0.1:7379> JSON.SET user:1001 $ '{"name": "John Doe", "age": 30, "email": "john.doe@example.com"}'
OK
127.0.0.1:7379> JSON.GET user:1001
"{\"name\":\"John Doe\",\"age\":30,\"email\":\"john.doe@example.com\"}"

Retrieve Specific Field from JSON Document

127.0.0.1:7379> JSON.SET user:1001 $ '{"name": "John Doe", "age": 30, "email": "john.doe@example.com"}'
OK
127.0.0.1:7379> JSON.GET user:1001 $.name
"\"John Doe\""

Retrieve Nested Field from JSON Document

127.0.0.1:7379> JSON.SET user:1002 $ '{"name": "Jane Doe", "address": {"city": "New York", "zip": "10001"}}'
OK
127.0.0.1:7379> JSON.GET user:1002 $.address.city
"\"New York\""

Handling Non-Existent Key

127.0.0.1:7379> JSON.GET user:9999
(nil)

Handling Non-Existent Path

127.0.0.1:7379> JSON.SET user:1001 $ '{"name": "John Doe", "age": 30, "email": "john.doe@example.com"}'
OK
127.0.0.1:7379> JSON.GET user:1001 $.nonexistent
(error) ERR Path '$.nonexistent' does not exist

Notes

• JSONPath expressions allow you to navigate and retrieve specific parts of a JSON document. Ensure that your JSONPath expressions are correctly formatted to avoid errors.

By understanding the JSON.GET command, you can efficiently retrieve JSON data stored in your DiceDB database, enabling you to build powerful and flexible applications that leverage the capabilities of DiceDB.