MDEV-25875 JSON_TABLE: extract document fragment into JSON column.

treat values insertedn into JSON column as JSON.

mysql-test/suite/json/r/json_table.result

@@ -953,6 +953,23 @@ converted	original
 Warnings:
 Warning	1264	Out of range value for column 'converted' at row 2
 Warning	1366	Incorrect integer value: 'foo' for column ``.`(temporary)`.`converted` at row 3
+select * from
+json_table('[{"color": "blue",  "price": { "high": 10, "low": 5}},
+               {"color": "white",   "price": "pretty low"},
+               {"color": "yellow",  "price": 256.20},
+               {"color": "red",   "price": { "high": 20, "low": 8}}]',
+'$[*]' columns(color varchar(100) path '$.color',
+price json path '$.price'
+                        )
+) as T;
+color	price
+blue	{ "high": 10, "low": 5}
+white	"pretty low"
+yellow	256.20
+red	{ "high": 20, "low": 8}
+select * from  json_table('{"foo": null}', '$' columns( jscol json path '$.foo')) as T;
+jscol
+null
 #
 # End of 10.6 tests
 #

mysql-test/suite/json/r/json_table_mysql.result

@@ -40,7 +40,7 @@ id	jpath	jsn_path	jexst
 2	2	2	0
 3	33	{"x":33}	1
 4	0	0	0
-5	66	NULL	0
+5	66	[1,2]	0
 select * from
 json_table(
 '[{"a":"3"},{"a":2},{"b":1},{"a":0.33},{"a":"asd"}]',
@@ -55,11 +55,11 @@ jsn_path json path '$.a' default '{"x":33}' on empty,
 jexst int exists path '$.b')
 ) as tt;
 id	jpath_i	jpath_r	jsn_path	jexst
-1	3	3	3	0
+1	3	3	"3"	0
 2	2	2	2	0
 3	33	33.3	{"x":33}	1
 4	0	0.33	0.33	0
-5	0	0	asd	0
+5	0	0	"asd"	0
 Warnings:
 Warning	1366	Incorrect integer value: 'asd' for column ``.`(temporary)`.`jpath_i` at row 5
 Warning	1366	Incorrect double value: 'asd' for column ``.`(temporary)`.`jpath_r` at row 5
@@ -78,7 +78,7 @@ id	jpath	jsn_path	jexst
 2	2	2	0
 3	33	{"x":33}	1
 4	0	0	0
-5	66	NULL	0
+5	66	[1,2]	0
 select * from
 json_table(
 '[{"a":"3"},{"a":2},{"b":1},{"a":0}]',
@@ -88,7 +88,7 @@ json_path json path '$.a',
 jexst int exists path '$.b')
 ) as tt;
 id	jpath	json_path	jexst
-1	3	3	0
+1	3	"3"	0
 2	2	2	0
 3	NULL	NULL	1
 4	0	0	0
@@ -315,24 +315,24 @@ id1	jpath	jexst	id2	id3	jpath_3	id4	jpath_4
 1	3	0	2	1	a1	NULL	NULL
 1	3	0	2	2	a2	NULL	NULL
 1	3	0	3	1	c	NULL	NULL
-1	3	0	NULL	NULL	NULL	1	NULL
-1	3	0	NULL	NULL	NULL	2	NULL
-1	3	0	NULL	NULL	NULL	3	NULL
+1	3	0	NULL	NULL	NULL	1	{"ll":["b1","b2","b3"]}
+1	3	0	NULL	NULL	NULL	2	{"ll": ["a1","a2"]}
+1	3	0	NULL	NULL	NULL	3	{"ll":["c"]}
 2	2	0	1	1	1	NULL	NULL
 2	2	0	1	2	11	NULL	NULL
 2	2	0	1	3	111	NULL	NULL
 2	2	0	2	1	2	NULL	NULL
-2	2	0	NULL	NULL	NULL	1	NULL
-2	2	0	NULL	NULL	NULL	2	NULL
+2	2	0	NULL	NULL	NULL	1	{"ll":[1,11,111]}
+2	2	0	NULL	NULL	NULL	2	{"ll":[2]}
 3	NULL	1	1	1	zzz	NULL	NULL
-3	NULL	1	NULL	NULL	NULL	1	NULL
+3	NULL	1	NULL	NULL	NULL	1	{"ll":["zzz"]}
 4	0	0	1	1	0.1	NULL	NULL
 4	0	0	1	2	0.01	NULL	NULL
 4	0	0	2	1	0.02	NULL	NULL
 4	0	0	2	2	0.002	NULL	NULL
 4	0	0	2	3	0.0002	NULL	NULL
-4	0	0	NULL	NULL	NULL	1	NULL
-4	0	0	NULL	NULL	NULL	2	NULL
+4	0	0	NULL	NULL	NULL	1	{"ll":[0.1,0.01]}
+4	0	0	NULL	NULL	NULL	2	{"ll":[0.02,0.002,0.0002]}
 ord should be 1,1,1,2, which tells that first two values of 'l' are
 from the same object, and next two are from different objects
 SELECT *
@@ -604,7 +604,7 @@ SELECT * FROM JSON_TABLE('{"a":"1"}',
 o FOR ORDINALITY)) AS jt
 WHERE o = 1;
 jpath	o
-1	1
+"1"	1
 #
 # Bug#25427982: ASSERTION `DERIVED' FAILED IN SQL/TABLE.H
 #

mysql-test/suite/json/t/json_table.test

@@ -180,6 +180,7 @@ from
   json_table(JS1.size, '$' columns (size INT PATH '$.size')) as JS2,
   json_table(JS1.size, '$' columns (size INT PATH '$.size')) as JS3 where  1;
 
+
 create table t1 (json varchar(100) character set utf8);
 insert into t1 values ('{"value":"АБВ"}');
 create table tj1 as 
@@ -814,6 +815,21 @@ select * from json_table('{"a":"foo", "b":1, "c":1000}', '$.*' columns(converted
 
 select * from json_table('{"a":"foo", "b":1, "c":1000}', '$.*' columns(converted tinyint path '$', original text path '$')) as jt order by original;
 
+#
+# MDEV-25875 SON_TABLE: extract document fragment into JSON column.
+#
+
+select * from
+  json_table('[{"color": "blue",  "price": { "high": 10, "low": 5}},
+               {"color": "white",   "price": "pretty low"},
+               {"color": "yellow",  "price": 256.20},
+               {"color": "red",   "price": { "high": 20, "low": 8}}]',
+             '$[*]' columns(color varchar(100) path '$.color',
+                          price json path '$.price'
+                        )
+             ) as T;
+
+select * from  json_table('{"foo": null}', '$' columns( jscol json path '$.foo')) as T;
 --echo #
 --echo # End of 10.6 tests
 --echo #

sql/json_table.cc

@@ -19,6 +19,7 @@
 #include "sql_priv.h"
 #include "sql_class.h" /* TMP_TABLE_PARAM */
 #include "table.h"
+#include "sql_type_json.h"
 #include "item_jsonfunc.h"
 #include "json_table.h"
 #include "sql_show.h"
@@ -377,6 +378,30 @@ static void store_json_in_field(Field *f, const json_engine_t *je)
 }
 
 
+/*
+  Store the current JSON element pointed by je into field f, as a separate
+  JSON document.
+*/
+
+static int store_value_as_json_doc(Field *f, json_engine_t *je)
+{
+  const uchar *from= je->value_begin;
+  const uchar *to;
+
+  if (json_value_scalar(je))
+    to= je->value_end;
+  else
+  {
+    int error;
+    if ((error= json_skip_level(je)))
+      return error;
+    to= je->s.c_str;
+  }
+  f->store((const char *) from, (uint32) (to - from), je->s.cs);
+  return 0;
+}
+
+
 bool Json_table_nested_path::check_error(const char *str)
 {
   if (m_engine.s.error)
@@ -541,7 +566,12 @@ int ha_json_table::fill_column_values(THD *thd, uchar * buf, uchar *pos)
           }
           else
           {
-            if (!(error= !json_value_scalar(&je)))
+            if (jc->m_format_json)
+            {
+              if (!(error= store_value_as_json_doc(*f, &je)))
+                error= er_handler.errors;
+            }
+            else if (!(error= !json_value_scalar(&je)))
             {
               store_json_in_field(*f, &je);
               error= er_handler.errors;
@@ -868,6 +898,11 @@ int Json_table_column::set(THD *thd, enum_type ctype, const LEX_CSTRING &path)
     anctual content. Not sure though if we should.
   */
   m_path.s.c_str= (const uchar *) path.str;
+
+  if (ctype == PATH)
+    m_format_json=
+      MY_TEST(m_field->type_handler() == &type_handler_json_longtext);
+
   return 0;
 }
 

sql/json_table.h

@@ -147,6 +147,7 @@ class Json_table_column : public Sql_alloc
   };
 
   enum_type m_column_type;
+  bool m_format_json;
   json_path_t m_path;
   On_response m_on_error;
   On_response m_on_empty;