datafusion-functions-json

Note: This is not an official Apache Software Foundation release, see datafusion-contrib/datafusion-functions-json#5.

This crate provides a set of functions for querying JSON strings in DataFusion. The functions are implemented as scalar functions that can be used in SQL queries.

To use these functions, you'll just need to call:

datafusion_functions_json::register_all(&mut ctx)?;

To register the below JSON functions in your SessionContext.

Done

• [x] json_contains(json: str, *keys: str | int) -> bool - true if a JSON object has a specific key
• [x] json_get(json: str, *keys: str | int) -> JsonUnion - Get a value from a JSON object by its "path"
• [x] json_get_str(json: str, *keys: str | int) -> str - Get a string value from a JSON object by its "path"
• [x] json_get_int(json: str, *keys: str | int) -> int - Get an integer value from a JSON object by its "path"
• [x] json_get_float(json: str, *keys: str | int) -> float - Get a float value from a JSON object by its "path"
• [x] json_get_bool(json: str, *keys: str | int) -> bool - Get a boolean value from a JSON object by its "path"
• [x] json_get_json(json: str, *keys: str | int) -> str - Get any value from a JSON object by its "path", represented as a string
• [x] json_length(json: str, *keys: str | int) -> int - get the length of a JSON object or array

Cast expressions with json_get are rewritten to the appropriate method, e.g.

select * from foo where json_get(attributes, 'bar')::string='ham'

Will be rewritten to:

select * from foo where json_get_str(attributes, 'bar')='ham'

TODO (maybe, if they're actually useful)

• [ ] json_keys(json: str, *keys: str | int) -> list[str] - get the keys of a JSON object
• [ ] json_is_obj(json: str, *keys: str | int) -> bool - true if the JSON is an object
• [ ] json_is_array(json: str, *keys: str | int) -> bool - true if the JSON is an array
• [ ] json_valid(json: str) -> bool - true if the JSON is valid