json_array_elements and json_build_object in Datafusion?

[dadepo]

From looking around the documentation, it looks like Datafusion does not natively have any functionality comparable to json_array_elements and json_build_object?

json_array_elements for allows arrays to be treated as rows
json_build_object for constructing json object from column values

See postgresql documentation for reference https://www.postgresql.org/docs/current/functions-json.html

Is this the case? or there are ways to kinda achieve the same thing natively in Datafusion?

[Jefffrey]

For json_build_object we do now have make_map which seems to achieve something similar:

datafusion/datafusion/sqllogictest/test_files/map.slt

Lines 132 to 135 in 48cc4c8

	query ?
	SELECT MAKE_MAP('POST', 41, 'HEAD', 33, 'PATCH', null);
	----
	{POST: 41, HEAD: 33, PATCH: NULL}

• https://datafusion.apache.org/user-guide/sql/scalar_functions.html#map

For json_array_elements, I don't think we have anything similar in DataFusion at the moment. I guess it would be classified as a table function, and you can see an example of implementing a custom user defined table function here:

https://github.com/apache/datafusion/blob/main/datafusion-examples/examples/udf/simple_udtf.rs