Transforms for jsonb to PL/Python

Add a new contrib module jsonb_plpython that provide a transform between
jsonb and PL/Python.  jsonb values are converted to appropriate Python
types such as dicts and lists, and vice versa.

Author: Anthony Bykov <a.bykov@postgrespro.ru>
Reviewed-by: Aleksander Alekseev <a.alekseev@postgrespro.ru>
Reviewed-by: Nikita Glukhov <n.gluhov@postgrespro.ru>

contrib/jsonb_plpython/sql/jsonb_plpython.sql

@@ -0,0 +1,218 @@
+CREATE EXTENSION jsonb_plpython2u CASCADE;
+
+-- test jsonb -> python dict
+CREATE FUNCTION test1(val jsonb) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert isinstance(val, dict)
+plpy.info(sorted(val.items()))
+return len(val)
+$$;
+
+SELECT test1('{"a": 1, "c": "NULL"}'::jsonb);
+
+-- test jsonb -> python dict
+-- complex dict with dicts as value
+CREATE FUNCTION test1complex(val jsonb) RETURNS int
+LANGUAGE plpython2u
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert isinstance(val, dict)
+assert(val == {"d": {"d": 1}})
+return len(val)
+$$;
+
+SELECT test1complex('{"d": {"d": 1}}'::jsonb);
+
+
+-- test jsonb[] -> python dict
+-- dict with array as value
+CREATE FUNCTION test1arr(val jsonb) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert isinstance(val, dict)
+assert(val == {"d": [12, 1]})
+return len(val)
+$$;
+
+SELECT test1arr('{"d":[12, 1]}'::jsonb);
+
+-- test jsonb[] -> python list
+-- simple list
+CREATE FUNCTION test2arr(val jsonb) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert isinstance(val, list)
+assert(val == [12, 1])
+return len(val)
+$$;
+
+SELECT test2arr('[12, 1]'::jsonb);
+
+-- test jsonb[] -> python list
+-- array of dicts
+CREATE FUNCTION test3arr(val jsonb) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert isinstance(val, list)
+assert(val == [{"a": 1,"b": 2}, {"c": 3,"d": 4}])
+return len(val)
+$$;
+
+SELECT test3arr('[{"a": 1, "b": 2}, {"c": 3,"d": 4}]'::jsonb);
+
+-- test jsonb int -> python int
+CREATE FUNCTION test1int(val jsonb) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert(val == 1)
+return val
+$$;
+
+SELECT test1int('1'::jsonb);
+
+-- test jsonb string -> python string
+CREATE FUNCTION test1string(val jsonb) RETURNS text
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert(val == "a")
+return val
+$$;
+
+SELECT test1string('"a"'::jsonb);
+
+-- test jsonb null -> python None
+CREATE FUNCTION test1null(val jsonb) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+assert(val == None)
+return 1
+$$;
+
+SELECT test1null('null'::jsonb);
+
+-- test python -> jsonb
+CREATE FUNCTION roundtrip(val jsonb) RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+as $$
+return val
+$$;
+
+SELECT roundtrip('null'::jsonb);
+SELECT roundtrip('1'::jsonb);
+SELECT roundtrip('1234567890.0987654321'::jsonb);
+SELECT roundtrip('-1234567890.0987654321'::jsonb);
+SELECT roundtrip('true'::jsonb);
+SELECT roundtrip('"string"'::jsonb);
+
+SELECT roundtrip('{"1": null}'::jsonb);
+SELECT roundtrip('{"1": 1}'::jsonb);
+SELECT roundtrip('{"1": true}'::jsonb);
+SELECT roundtrip('{"1": "string"}'::jsonb);
+
+SELECT roundtrip('[null]'::jsonb);
+SELECT roundtrip('[1]'::jsonb);
+SELECT roundtrip('[true]'::jsonb);
+SELECT roundtrip('["string"]'::jsonb);
+SELECT roundtrip('[null, 1]'::jsonb);
+SELECT roundtrip('[1, true]'::jsonb);
+SELECT roundtrip('[true, "string"]'::jsonb);
+SELECT roundtrip('["string", "string2"]'::jsonb);
+
+-- test python infinity -> jsonb
+CREATE FUNCTION test1inf() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = float('inf')
+print(x)
+return x
+$$;
+
+SELECT test1inf();
+
+-- test python -infinity -> jsonb
+CREATE FUNCTION test2inf() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = float('-inf')
+print(x)
+return x
+$$;
+
+SELECT test2inf();
+
+-- test python NaN -> jsonb
+CREATE FUNCTION test1nan() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = float('nan')
+return x
+$$;
+
+SELECT test1nan();
+
+-- complex numbers -> jsonb
+CREATE FUNCTION testComplexNumbers() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = 1 + 2j
+return x
+$$;
+
+SELECT testComplexNumbers();
+
+-- range -> jsonb
+CREATE FUNCTION testRange() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = range(3)
+return x
+$$;
+
+SELECT testRange();
+
+-- 0xff -> jsonb
+CREATE FUNCTION testDecimal() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = 0xff
+return x
+$$;
+
+SELECT testDecimal();
+
+-- tuple -> jsonb
+CREATE FUNCTION testTuple() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = (1, 'String', None)
+return x
+$$;
+
+SELECT testTuple();
+
+-- interesting dict -> jsonb
+CREATE FUNCTION test_dict1() RETURNS jsonb
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE jsonb
+AS $$
+x = {"a": 1, None: 2, 33: 3}
+return x
+$$;
+
+SELECT test_dict1();