Allow jsonpath $ everywhere

Author: Nikita Glukhov

src/backend/utils/adt/jsonpath.c

@@ -25,7 +25,7 @@
  */
 static int
 flattenJsonPathParseItem(StringInfo buf, JsonPathParseItem *item,
-						 bool forbiddenRoot, bool insideArraySubscript)
+						 bool allowCurrent, bool insideArraySubscript)
 {
 	/* position from begining of jsonpath data */
 	int32	pos = buf->len - JSONPATH_HDRSZ;
@@ -90,11 +90,11 @@ flattenJsonPathParseItem(StringInfo buf, JsonPathParseItem *item,
 				appendBinaryStringInfo(buf, (char*)&right /* fake value */, sizeof(right));
 
 				chld = flattenJsonPathParseItem(buf, item->value.args.left,
-												forbiddenRoot,
+												allowCurrent,
 												insideArraySubscript);
 				*(int32*)(buf->data + left) = chld;
 				chld = flattenJsonPathParseItem(buf, item->value.args.right,
-												forbiddenRoot,
+												allowCurrent,
 												insideArraySubscript);
 				*(int32*)(buf->data + right) = chld;
 			}
@@ -122,24 +122,20 @@ flattenJsonPathParseItem(StringInfo buf, JsonPathParseItem *item,
 
 				chld = flattenJsonPathParseItem(buf, item->value.arg,
 												item->type == jpiFilter ||
-												forbiddenRoot,
+												allowCurrent,
 												insideArraySubscript);
 				*(int32*)(buf->data + arg) = chld;
 			}
 			break;
 		case jpiNull:
 			break;
 		case jpiRoot:
-			if (forbiddenRoot)
-				ereport(ERROR,
-						(errcode(ERRCODE_SYNTAX_ERROR),
-						 errmsg("root is not allowed in expression")));
 			break;
 		case jpiAnyArray:
 		case jpiAnyKey:
 			break;
 		case jpiCurrent:
-			if (!forbiddenRoot)
+			if (!allowCurrent)
 				ereport(ERROR,
 						(errcode(ERRCODE_SYNTAX_ERROR),
 						 errmsg("@ is not allowed in root expressions")));
@@ -207,7 +203,7 @@ flattenJsonPathParseItem(StringInfo buf, JsonPathParseItem *item,
 
 	if (item->next)
 		*(int32*)(buf->data + next) =
-			flattenJsonPathParseItem(buf, item->next, forbiddenRoot,
+			flattenJsonPathParseItem(buf, item->next, allowCurrent,
 									 insideArraySubscript);
 
 	return  pos;

src/backend/utils/adt/jsonpath_exec.c

@@ -26,6 +26,7 @@ typedef struct JsonPathExecContext
 {
 	List	   *vars;
 	bool		lax;
+	JsonbValue *root;				/* for $ evaluation */
 	int			innermostArraySize;	/* for LAST array index evaluation */
 } JsonPathExecContext;
 
@@ -1059,6 +1060,9 @@ recursiveExecuteNoUnwrap(JsonPathExecContext *cxt, JsonPathItem *jsp,
 			else if (!cxt->lax && found)	/* XXX deviation from standard */
 				res = jperMakeError(ERRCODE_JSON_MEMBER_NOT_FOUND);
 			break;
+		case jpiRoot:
+			jb = cxt->root;
+			/* fall through */
 		case jpiCurrent:
 			if (!jspGetNext(jsp, &elem))
 			{
@@ -1318,19 +1322,6 @@ recursiveExecuteNoUnwrap(JsonPathExecContext *cxt, JsonPathItem *jsp,
 		case jpiPlus:
 		case jpiMinus:
 			res = executeUnaryArithmExpr(cxt, jsp, jb, found);
-			break;
-		case jpiRoot:
-			if (jspGetNext(jsp, &elem))
-			{
-				res = recursiveExecute(cxt, &elem, jb, found);
-			}
-			else
-			{
-				res = jperOk;
-				if (found)
-					*found = lappend(*found, copyJsonbValue(jb));
-			}
-
 			break;
 		case jpiFilter:
 			jspGetArg(jsp, &elem);
@@ -1852,6 +1843,7 @@ executeJsonPath(JsonPath *path, List *vars, Jsonb *json, List **foundJson)
 
 	cxt.vars = vars;
 	cxt.lax = (path->header & JSONPATH_LAX) != 0;
+	cxt.root = &jbv;
 	cxt.innermostArraySize = -1;
 
 	return recursiveExecute(&cxt, &jsp, &jbv, foundJson);

src/test/regress/expected/jsonb_jsonpath.out

@@ -634,6 +634,12 @@ select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$.c ? (.a == .b)');
  t
 (1 row)
 
+select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$.c ? ($.c.a == .b)');
+ _jsonpath_exists 
+------------------
+ t
+(1 row)
+
 select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$.* ? (.a == .b)');
  _jsonpath_exists 
 ------------------
@@ -742,6 +748,12 @@ select _jsonpath_exists(jsonb '[1,2,3]', '$ ? (-@[*] < -3)');
  f
 (1 row)
 
+select _jsonpath_exists(jsonb '1', '$ ? ($ > 0)');
+ _jsonpath_exists 
+------------------
+ t
+(1 row)
+
 -- unwrapping of operator arguments in lax mode
 select _jsonpath_query(jsonb '{"a": [2]}', 'lax $.a * 3');
  _jsonpath_query 

src/test/regress/expected/jsonpath.out

@@ -173,6 +173,12 @@ select '$.a/+-1'::jsonpath;
  ($."a" / -1)
 (1 row)
 
+select '$.g ? ($.a == 1)'::jsonpath;
+      jsonpath      
+--------------------
+ $."g"?($."a" == 1)
+(1 row)
+
 select '$.g ? (@ == 1)'::jsonpath;
     jsonpath    
 ----------------
@@ -311,6 +317,12 @@ select '$.a[$a + 1, ($b[*]) to -(@[0] * 2)]'::jsonpath;
  $."a"[$"a" + 1,$"b"[*] to -(@[0] * 2)]
 (1 row)
 
+select '$.a[$.a.size() - 3]'::jsonpath;
+        jsonpath         
+-------------------------
+ $."a"[$."a".size() - 3]
+(1 row)
+
 select 'last'::jsonpath;
 ERROR:  LAST is allowed only in array subscripts
 LINE 1: select 'last'::jsonpath;

src/test/regress/sql/jsonb_jsonpath.sql

@@ -131,6 +131,7 @@ from
 select _jsonpath_exists(jsonb '{"a": 1, "b":1}', '$ ? (.a == .b)');
 select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$ ? (.a == .b)');
 select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$.c ? (.a == .b)');
+select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$.c ? ($.c.a == .b)');
 select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$.* ? (.a == .b)');
 select _jsonpath_exists(jsonb '{"a": 1, "b":1}', '$.** ? (.a == .b)');
 select _jsonpath_exists(jsonb '{"c": {"a": 1, "b":1}}', '$.** ? (.a == .b)');
@@ -150,6 +151,7 @@ select _jsonpath_exists(jsonb '[1,2,3]', '$ ? (+@[*] > +2)');
 select _jsonpath_exists(jsonb '[1,2,3]', '$ ? (+@[*] > +3)');
 select _jsonpath_exists(jsonb '[1,2,3]', '$ ? (-@[*] < -2)');
 select _jsonpath_exists(jsonb '[1,2,3]', '$ ? (-@[*] < -3)');
+select _jsonpath_exists(jsonb '1', '$ ? ($ > 0)');
 
 -- unwrapping of operator arguments in lax mode
 select _jsonpath_query(jsonb '{"a": [2]}', 'lax $.a * 3');

src/test/regress/sql/jsonpath.sql

@@ -30,6 +30,7 @@ select '$-1'::jsonpath;
 select '$--+1'::jsonpath;
 select '$.a/+-1'::jsonpath;
 
+select '$.g ? ($.a == 1)'::jsonpath;
 select '$.g ? (@ == 1)'::jsonpath;
 select '$.g ? (a == 1)'::jsonpath;
 select '$.g ? (.a == 1)'::jsonpath;
@@ -54,6 +55,7 @@ select '$.g ? (zip == $zip)'::jsonpath;
 select '$.a.[1,2, 3 to 16]'::jsonpath;
 select '$.a[1,2, 3 to 16]'::jsonpath;
 select '$.a[$a + 1, ($b[*]) to -(@[0] * 2)]'::jsonpath;
+select '$.a[$.a.size() - 3]'::jsonpath;
 select 'last'::jsonpath;
 select '"last"'::jsonpath;
 select '$.last'::jsonpath;