Add _jsonpath_predicate()

Author: Nikita Glukhov

src/backend/utils/adt/jsonpath_exec.c

@@ -2372,6 +2372,52 @@ jsonb_jsonpath_exists3(PG_FUNCTION_ARGS)
 	return jsonb_jsonpath_exists(fcinfo);
 }
 
+static inline Datum
+jsonb_jsonpath_predicate(FunctionCallInfo fcinfo, List *vars)
+{
+	Jsonb	   *jb = PG_GETARG_JSONB_P(0);
+	JsonPath   *jp = PG_GETARG_JSONPATH_P(1);
+	JsonbValue *jbv;
+	JsonValueList found = { 0 };
+	JsonPathExecResult res;
+
+	res = executeJsonPath(jp, vars, jb, &found);
+
+	throwJsonPathError(res);
+
+	if (JsonValueListLength(&found) != 1)
+		throwJsonPathError(jperMakeError(ERRCODE_SINGLETON_JSON_ITEM_REQUIRED));
+
+	jbv = JsonValueListHead(&found);
+
+	if (JsonbType(jbv) == jbvScalar)
+		JsonbExtractScalar(jbv->val.binary.data, jbv);
+
+	PG_FREE_IF_COPY(jb, 0);
+	PG_FREE_IF_COPY(jp, 1);
+
+	if (jbv->type == jbvNull)
+		PG_RETURN_NULL();
+
+	if (jbv->type != jbvBool)
+		PG_RETURN_NULL(); /* XXX */
+
+	PG_RETURN_BOOL(jbv->val.boolean);
+}
+
+Datum
+jsonb_jsonpath_predicate2(PG_FUNCTION_ARGS)
+{
+	return jsonb_jsonpath_predicate(fcinfo, NIL);
+}
+
+Datum
+jsonb_jsonpath_predicate3(PG_FUNCTION_ARGS)
+{
+	return jsonb_jsonpath_predicate(fcinfo,
+									makePassingVars(PG_GETARG_JSONB_P(2)));
+}
+
 static Datum
 jsonb_jsonpath_query(FunctionCallInfo fcinfo)
 {

src/include/catalog/pg_proc.dat

@@ -9124,6 +9124,13 @@
   proname => '_jsonpath_query', prorows => '1000', proretset => 't',
   prorettype => 'jsonb', proargtypes => 'jsonb jsonpath jsonb',
   prosrc => 'jsonb_jsonpath_query3' },
+{ oid => '6073', descr => 'jsonpath predicate test',
+  proname => '_jsonpath_predicate', prorettype => 'bool',
+  proargtypes => 'jsonb jsonpath', prosrc => 'jsonb_jsonpath_predicate2' },
+{ oid => '6074', descr => 'jsonpath predicate test',
+  proname => '_jsonpath_predicate', prorettype => 'bool',
+  proargtypes => 'jsonb jsonpath jsonb',
+  prosrc => 'jsonb_jsonpath_predicate3' },
 
 # txid
 { oid => '2939', descr => 'I/O',

src/test/regress/expected/jsonb_jsonpath.out

@@ -820,6 +820,58 @@ select _jsonpath_query(jsonb '2', '$ == "2"');
  null
 (1 row)
 
+select _jsonpath_predicate(jsonb '2', '$ > 1');
+ _jsonpath_predicate 
+---------------------
+ t
+(1 row)
+
+select _jsonpath_predicate(jsonb '2', '$ <= 1');
+ _jsonpath_predicate 
+---------------------
+ f
+(1 row)
+
+select _jsonpath_predicate(jsonb '2', '$ == "2"');
+ _jsonpath_predicate 
+---------------------
+ 
+(1 row)
+
+select _jsonpath_predicate(jsonb '2', '1');
+ _jsonpath_predicate 
+---------------------
+ 
+(1 row)
+
+select _jsonpath_predicate(jsonb '{}', '$');
+ _jsonpath_predicate 
+---------------------
+ 
+(1 row)
+
+select _jsonpath_predicate(jsonb '[]', '$');
+ _jsonpath_predicate 
+---------------------
+ 
+(1 row)
+
+select _jsonpath_predicate(jsonb '[1,2,3]', '$[*]');
+ERROR:  Singleton SQL/JSON item required
+select _jsonpath_predicate(jsonb '[]', '$[*]');
+ERROR:  Singleton SQL/JSON item required
+select _jsonpath_predicate(jsonb '[[1, true], [2, false]]', 'strict $[*] ? (@[0] > $x) [1]', '{"x": 1}');
+ _jsonpath_predicate 
+---------------------
+ f
+(1 row)
+
+select _jsonpath_predicate(jsonb '[[1, true], [2, false]]', 'strict $[*] ? (@[0] < $x) [1]', '{"x": 2}');
+ _jsonpath_predicate 
+---------------------
+ t
+(1 row)
+
 select _jsonpath_query(jsonb '[null,1,true,"a",[],{}]', '$.type()');
  _jsonpath_query 
 -----------------

src/test/regress/sql/jsonb_jsonpath.sql

@@ -168,6 +168,17 @@ select _jsonpath_query(jsonb '2', '$ > 1');
 select _jsonpath_query(jsonb '2', '$ <= 1');
 select _jsonpath_query(jsonb '2', '$ == "2"');
 
+select _jsonpath_predicate(jsonb '2', '$ > 1');
+select _jsonpath_predicate(jsonb '2', '$ <= 1');
+select _jsonpath_predicate(jsonb '2', '$ == "2"');
+select _jsonpath_predicate(jsonb '2', '1');
+select _jsonpath_predicate(jsonb '{}', '$');
+select _jsonpath_predicate(jsonb '[]', '$');
+select _jsonpath_predicate(jsonb '[1,2,3]', '$[*]');
+select _jsonpath_predicate(jsonb '[]', '$[*]');
+select _jsonpath_predicate(jsonb '[[1, true], [2, false]]', 'strict $[*] ? (@[0] > $x) [1]', '{"x": 1}');
+select _jsonpath_predicate(jsonb '[[1, true], [2, false]]', 'strict $[*] ? (@[0] < $x) [1]', '{"x": 2}');
+
 select _jsonpath_query(jsonb '[null,1,true,"a",[],{}]', '$.type()');
 select _jsonpath_query(jsonb '[null,1,true,"a",[],{}]', 'lax $.type()');
 select _jsonpath_query(jsonb '[null,1,true,"a",[],{}]', '$[*].type()');