MDEV-25822 JSON_TABLE: default values should allow non-string literals

(Polished initial patch by Alexey Botchkov)
Make the code handle DEFAULT values of any datatype

- Make Json_table_column::On_response::m_default be Item*, not LEX_STRING.
- Change the parser to use string literal non-terminals for producing
  the DEFAULT value
-- Also, stop updating json_table->m_text_literal_cs for the DEFAULT
   value literals as it is not used.

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

@@ -1036,5 +1036,50 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	DEPENDENT SUBQUERY	jt	ALL	NULL	NULL	NULL	NULL	40	Table function: json_table
 drop table t1;
 #
+# MDEV-25822: JSON_TABLE: default values should allow non-string literals
+#
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 0.5 on empty)) as T;
+col1
+0.5
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 5 on empty)) as T;
+col1
+5
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 'asdf' on empty)) as T;
+col1
+asdf
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default -0.5 on empty)) as T;
+col1
+-0.5
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 18446744073709551615 on empty)) as T;
+col1
+18446744073709551615
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default DATE '2021-01-01' on empty)) as T;
+col1
+2021-01-01
+create view v as select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 5 on empty)) as T;
+select * from v;
+col1
+5
+show create view v;
+View	Create View	character_set_client	collation_connection
+v	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v` AS select `T`.`col1` AS `col1` from JSON_TABLE('{"a": "b"}', '$' COLUMNS (`col1` varchar(32) PATH '$.fooo' DEFAULT 5 ON EMPTY)) `T`	latin1	latin1_swedish_ci
+drop view v;
+create view v as select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 18446744073709551615 on empty)) as T;
+select * from v;
+col1
+18446744073709551615
+show create view v;
+View	Create View	character_set_client	collation_connection
+v	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v` AS select `T`.`col1` AS `col1` from JSON_TABLE('{"a": "b"}', '$' COLUMNS (`col1` varchar(32) PATH '$.fooo' DEFAULT 18446744073709551615 ON EMPTY)) `T`	latin1	latin1_swedish_ci
+drop view v;
+create view v as select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 'asdf' on empty)) as T;
+select * from v;
+col1
+asdf
+show create view v;
+View	Create View	character_set_client	collation_connection
+v	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v` AS select `T`.`col1` AS `col1` from JSON_TABLE('{"a": "b"}', '$' COLUMNS (`col1` varchar(32) PATH '$.fooo' DEFAULT 'asdf' ON EMPTY)) `T`	latin1	latin1_swedish_ci
+drop view v;
+#
 # End of 10.6 tests
 #

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

@@ -545,10 +545,12 @@ Warning	1366	Incorrect double value: 'asdf' for column ``.`(temporary)`.`f` at r
 Warning	1366	Incorrect decimal value: 'asdf' for column ``.`(temporary)`.`d` at row 1
 SELECT * FROM
 JSON_TABLE('{}', '$' COLUMNS (x INT PATH '$.x' DEFAULT NULL ON EMPTY)) jt;
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'NULL ON EMPTY)) jt' at line 2
+x
+NULL
 SELECT * FROM
 JSON_TABLE('{}', '$' COLUMNS (x INT PATH '$.x' DEFAULT NULL ON ERROR)) jt;
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'NULL ON ERROR)) jt' at line 2
+x
+NULL
 SELECT * FROM
 JSON_TABLE('{}', '$' COLUMNS (x INT PATH '$.x' DEFAULT 0 ON EMPTY)) jt;
 x
@@ -561,12 +563,14 @@ SELECT * FROM
 JSON_TABLE('{}', '$' COLUMNS (x DATE
 PATH '$.x'
                                   DEFAULT DATE'2020-01-01' ON EMPTY)) jt;
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'DATE'2020-01-01' ON EMPTY)) jt' at line 4
+x
+2020-01-01
 SELECT * FROM
 JSON_TABLE('{}', '$' COLUMNS (x DATE
 PATH '$.x'
                                   DEFAULT DATE'2020-01-01' ON ERROR)) jt;
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'DATE'2020-01-01' ON ERROR)) jt' at line 4
+x
+NULL
 #
 # Bug#25413069: SIG11 IN CHECK_COLUMN_GRANT_IN_TABLE_REF
 #

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

@@ -893,6 +893,30 @@ explain select c,
 
 drop table t1;
 
+--echo #
+--echo # MDEV-25822: JSON_TABLE: default values should allow non-string literals
+--echo #
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 0.5 on empty)) as T;
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 5 on empty)) as T;
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 'asdf' on empty)) as T;
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default -0.5 on empty)) as T;
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 18446744073709551615 on empty)) as T;
+select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default DATE '2021-01-01' on empty)) as T;
+
+create view v as select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 5 on empty)) as T;
+select * from v;
+show create view v;
+drop view v;
+create view v as select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 18446744073709551615 on empty)) as T;
+select * from v;
+show create view v;
+drop view v;
+create view v as select * from json_table('{"a": "b"}', '$' columns(col1 varchar(32) path '$.fooo' default 'asdf' on empty)) as T;
+select * from v;
+show create view v;
+drop view v;
+
+
 --echo #
 --echo # End of 10.6 tests
 --echo #

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

@@ -445,11 +445,8 @@ SELECT * FROM JSON_TABLE('"asdf"', '$' COLUMNS(
   f FLOAT PATH '$',
   d DECIMAL PATH '$')) AS jt;
 
-# DEFAULT NULL is not accepted syntax.
---error ER_PARSE_ERROR
 SELECT * FROM
   JSON_TABLE('{}', '$' COLUMNS (x INT PATH '$.x' DEFAULT NULL ON EMPTY)) jt;
---error ER_PARSE_ERROR
 SELECT * FROM
   JSON_TABLE('{}', '$' COLUMNS (x INT PATH '$.x' DEFAULT NULL ON ERROR)) jt;
 
@@ -457,13 +454,10 @@ SELECT * FROM
   JSON_TABLE('{}', '$' COLUMNS (x INT PATH '$.x' DEFAULT 0 ON EMPTY)) jt;
 SELECT * FROM
   JSON_TABLE('{}', '$' COLUMNS (x INT PATH '$.x' DEFAULT 0 ON ERROR)) jt;
-# We don't accept dates in DEFAULT
---error 1064
 SELECT * FROM
   JSON_TABLE('{}', '$' COLUMNS (x DATE
                                   PATH '$.x'
                                   DEFAULT DATE'2020-01-01' ON EMPTY)) jt;
---error 1064
 SELECT * FROM
   JSON_TABLE('{}', '$' COLUMNS (x DATE
                                   PATH '$.x'

sql/json_table.cc

@@ -1030,8 +1030,7 @@ int Json_table_column::On_response::respond(Json_table_column *jc, Field *f,
       return 1;
     case Json_table_column::RESPONSE_DEFAULT:
       f->set_notnull();
-      f->store(m_default.str,
-          m_default.length, jc->m_defaults_cs);
+      m_default->save_in_field(f, TRUE);
       break;
   }
   return 0;
@@ -1041,7 +1040,11 @@ int Json_table_column::On_response::respond(Json_table_column *jc, Field *f,
 int Json_table_column::On_response::print(const char *name, String *str) const
 {
   LEX_CSTRING resp;
-  const LEX_CSTRING *ds= NULL;
+
+  char valbuf[512];
+  String val(valbuf, sizeof(valbuf), str->charset());
+  String *ds= NULL;
+
   if (m_response == Json_table_column::RESPONSE_NOT_SPECIFIED)
     return 0;
 
@@ -1056,7 +1059,7 @@ int Json_table_column::On_response::print(const char *name, String *str) const
     case Json_table_column::RESPONSE_DEFAULT:
     {
       lex_string_set3(&resp, STRING_WITH_LEN("DEFAULT"));
-      ds= &m_default;
+      ds= m_default->val_str(&val);
       break;
     }
     default:
@@ -1065,9 +1068,14 @@ int Json_table_column::On_response::print(const char *name, String *str) const
   }
 
   return (str->append(' ') || str->append(resp)  ||
-          (ds && (str->append(STRING_WITH_LEN(" '")) ||
-                  str->append_for_single_quote(ds->str, ds->length) ||
-                  str->append('\''))) ||
+          (ds &&
+            (str->append(' ') ||
+             (m_default->result_type()==STRING_RESULT && str->append('\''))||
+
+             str->append_for_single_quote(ds) ||
+
+             (m_default->result_type()==STRING_RESULT && str->append('\''))))||
+
           str->append(STRING_WITH_LEN(" ON ")) ||
           str->append(name, strlen(name)));
 }

sql/json_table.h

@@ -140,7 +140,7 @@ class Json_table_column : public Sql_alloc
   {
   public:
     Json_table_column::enum_on_response m_response;
-    LEX_CSTRING m_default;
+    Item *m_default;
     int respond(Json_table_column *jc, Field *f, uint error_num);
     int print(const char *name, String *str) const;
     bool specified() const { return m_response != RESPONSE_NOT_SPECIFIED; }
@@ -154,7 +154,6 @@ class Json_table_column : public Sql_alloc
   Create_field *m_field;
   Json_table_nested_path *m_nest;
   CHARSET_INFO *m_explicit_cs;
-  CHARSET_INFO *m_defaults_cs;
 
   void set(enum_type ctype)
   {

sql/sql_yacc.yy

@@ -1328,7 +1328,6 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
         TEXT_STRING
         NCHAR_STRING
         json_text_literal
-        json_text_literal_or_num
 
 %type <lex_str_ptr>
         opt_table_alias_clause
@@ -1512,6 +1511,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
         simple_target_specification
         condition_number
         opt_versioning_interval_start
+        json_default_literal
 
 %type <item_param> param_marker
 
@@ -11595,26 +11595,6 @@ json_text_literal:
           }
         ;
 
-json_text_literal_or_num:
-          json_text_literal
-        | NUM
-          {
-            Lex->json_table->m_text_literal_cs= NULL;
-          }
-        | LONG_NUM
-          {
-            Lex->json_table->m_text_literal_cs= NULL;
-          }
-        | DECIMAL_NUM
-          {
-            Lex->json_table->m_text_literal_cs= NULL;
-          }
-        | FLOAT_NUM
-          {
-            Lex->json_table->m_text_literal_cs= NULL;
-          }
-        ;
-
 join_table_list:
           derived_table_list { MYSQL_YYABORT_UNLESS($$=$1); }
         ;
@@ -11720,6 +11700,12 @@ json_opt_on_empty_or_error:
         | json_on_empty_response json_on_error_response
         ;
 
+json_default_literal:
+          literal
+        | signed_literal
+        ;
+
+
 json_on_response:
           ERROR_SYM
           {
@@ -11729,12 +11715,10 @@ json_on_response:
           {
             $$.m_response= Json_table_column::RESPONSE_NULL;
           }
-        | DEFAULT json_text_literal_or_num
+        | DEFAULT json_default_literal
           {
             $$.m_response= Json_table_column::RESPONSE_DEFAULT;
             $$.m_default= $2;
-            Lex->json_table->m_cur_json_table_column->m_defaults_cs=
-                                    thd->variables.collation_connection;
           }
         ;