MDEV-25146 JSON_TABLE: Non-descriptive + wrong error messages upon trying to store array or object.

More informative messages added.
Do not issue additional messages if already handled.

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

@@ -88,7 +88,7 @@ a	b
 select * from JSON_TABLE( '[{"a": [1, 2], "b": [11,111]}, {"a": 2, "b": [22,222]}, {"a":3} xx YY]', '$[*]' COLUMNS( a INT PATH '$.a' default '202' on error default '101' on empty, NESTED PATH '$.b[*]' COLUMNS (b INT PATH '$'))) as jt;
 ERROR HY000: Syntax error in JSON text in argument 1 to function 'JSON_TABLE' at position 65
 select * from JSON_TABLE( '[{"a": [1, 2], "b": [11,111]}, {"a": 2, "b": [22,222]}, {"a":3}]', '$[*]' COLUMNS( a INT PATH '$.a' error on error default '101' on empty, NESTED PATH '$.b[*]' COLUMNS (b INT PATH '$'))) as jt;
-ERROR HY000: Field 'a' can't be set for JSON_TABLE 'jt'.
+ERROR HY000: Can't store an array or an object in the scalar column 'a' of JSON_TABLE 'jt'.
 select * from json_table('{"a":0}',"$" columns(a decimal(1,1) path '$.a')) foo;
 a
 0.0
@@ -573,5 +573,13 @@ id
 3
 drop table json_table;
 #
+# MDEV-25146 JSON_TABLE: Non-descriptive + wrong error messages upon trying to store array or object.
+#
+select a from json_table('[[]]', '$' columns(a char(8) path '$' error on error)) t;
+ERROR HY000: Can't store an array or an object in the scalar column 'a' of JSON_TABLE 't'.
+show warnings;
+Level	Code	Message
+Error	4177	Can't store an array or an object in the scalar column 'a' of JSON_TABLE 't'.
+#
 # End of 10.6 tests
 #

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

@@ -115,7 +115,7 @@ json_table(
 jpath varchar(100) path '$.a' error on error,
 jexst int exists path '$.b')
 ) as tt;
-ERROR HY000: Field 'jpath' can't be set for JSON_TABLE 'tt'.
+ERROR HY000: Can't store an array or an object in the scalar column 'jpath' of JSON_TABLE 'tt'.
 select * from
 json_table(
 '!#@$!@#$',
@@ -396,18 +396,18 @@ v	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIE
 DROP VIEW v;
 SELECT * FROM JSON_TABLE('"asdf"',
 '$' COLUMNS (a INT PATH '$' ERROR ON ERROR)) AS jt;
-ERROR HY000: Field 'a' can't be set for JSON_TABLE 'jt'.
+ERROR HY000: Can't store an array or an object in the scalar column 'a' of JSON_TABLE 'jt'.
 SELECT * FROM
 JSON_TABLE('[{"a":1},{"a":2}]',
 '$' COLUMNS (a INT PATH '$[*].a' ERROR ON ERROR)) AS jt;
-ERROR HY000: Field 'a' can't be set for JSON_TABLE 'jt'.
+ERROR HY000: Can't store multiple matches of the path in the column 'a' of JSON_TABLE 'jt'.
 SELECT * FROM
 JSON_TABLE('[{"a":1},{"a":2}]',
 '$' COLUMNS (a JSON PATH '$[*].a' ERROR ON ERROR)) AS jt;
-ERROR HY000: Field 'a' can't be set for JSON_TABLE 'jt'.
+ERROR HY000: Can't store multiple matches of the path in the column 'a' of JSON_TABLE 'jt'.
 SELECT * FROM
 JSON_TABLE('123.456', '$' COLUMNS (a DECIMAL(2,1) PATH '$' ERROR ON ERROR)) AS jt;
-ERROR HY000: Field 'a' can't be set for JSON_TABLE 'jt'.
+ERROR HY000: Can't store an array or an object in the scalar column 'a' of JSON_TABLE 'jt'.
 SELECT * FROM
 JSON_TABLE('123.456', '$' COLUMNS (a DECIMAL(2,1) PATH '$')) AS jt;
 a
@@ -811,7 +811,7 @@ SELECT * FROM
 JSON_TABLE('[3.14159]',
 '$[*]' COLUMNS (col18 DECIMAL(3,3) PATH '$' ERROR ON ERROR)
 ) AS alias2;
-ERROR HY000: Field 'col18' can't be set for JSON_TABLE 'alias2'.
+ERROR HY000: Can't store an array or an object in the scalar column 'col18' of JSON_TABLE 'alias2'.
 SELECT * FROM
 JSON_TABLE('[0.9]',
 '$[*]' COLUMNS (col18 DECIMAL(3,3) PATH '$')

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

@@ -41,7 +41,7 @@ select * from JSON_TABLE( '[ {"a": [1, 2], "b": [11,111]}, {"a": 2, "b": [22,222
 --error ER_JSON_SYNTAX
 select * from JSON_TABLE( '[{"a": [1, 2], "b": [11,111]}, {"a": 2, "b": [22,222]}, {"a":3} xx YY]', '$[*]' COLUMNS( a INT PATH '$.a' default '202' on error default '101' on empty, NESTED PATH '$.b[*]' COLUMNS (b INT PATH '$'))) as jt;
 
---error ER_JSON_TABLE_ERROR_ON_FIELD
+--error ER_JSON_TABLE_SCALAR_EXPECTED
 select * from JSON_TABLE( '[{"a": [1, 2], "b": [11,111]}, {"a": 2, "b": [22,222]}, {"a":3}]', '$[*]' COLUMNS( a INT PATH '$.a' error on error default '101' on empty, NESTED PATH '$.b[*]' COLUMNS (b INT PATH '$'))) as jt;
 
 #
@@ -446,6 +446,13 @@ insert into json_table values (1), (2), (3);
 select * from json_table;
 drop table json_table;
 
+--echo #
+--echo # MDEV-25146 JSON_TABLE: Non-descriptive + wrong error messages upon trying to store array or object.
+--echo #
+--error ER_JSON_TABLE_SCALAR_EXPECTED
+select a from json_table('[[]]', '$' columns(a char(8) path '$' error on error)) t;
+show warnings;
+
 --echo #
 --echo # End of 10.6 tests
 --echo #

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

@@ -91,7 +91,7 @@ select * from
              jexst int exists path '$.b')
   ) as tt;
 
---error ER_JSON_TABLE_ERROR_ON_FIELD
+--error ER_JSON_TABLE_SCALAR_EXPECTED
 select * from
   json_table(
     '[{"a":"3"},{"a":2},{"a":1},{"a":[0,1]}]',
@@ -327,20 +327,19 @@ SELECT * FROM v;
 SHOW CREATE VIEW v;
 DROP VIEW v;
 
---error ER_JSON_TABLE_ERROR_ON_FIELD
+--error ER_JSON_TABLE_SCALAR_EXPECTED
 SELECT * FROM JSON_TABLE('"asdf"',
                          '$' COLUMNS (a INT PATH '$' ERROR ON ERROR)) AS jt;
-#--error ER_WRONG_JSON_TABLE_VALUE
---error ER_JSON_TABLE_ERROR_ON_FIELD
+--error ER_JSON_TABLE_MULTIPLE_MATCHES
 SELECT * FROM
   JSON_TABLE('[{"a":1},{"a":2}]',
              '$' COLUMNS (a INT PATH '$[*].a' ERROR ON ERROR)) AS jt;
 # psergey-added:
---error ER_JSON_TABLE_ERROR_ON_FIELD
+--error ER_JSON_TABLE_MULTIPLE_MATCHES
 SELECT * FROM
   JSON_TABLE('[{"a":1},{"a":2}]',
              '$' COLUMNS (a JSON PATH '$[*].a' ERROR ON ERROR)) AS jt;
---error ER_JSON_TABLE_ERROR_ON_FIELD
+--error ER_JSON_TABLE_SCALAR_EXPECTED
 SELECT * FROM
   JSON_TABLE('123.456', '$' COLUMNS (a DECIMAL(2,1) PATH '$' ERROR ON ERROR)) AS jt;
 SELECT * FROM
@@ -722,7 +721,7 @@ SELECT * FROM
                 ) AS alias2;
 
 #--error ER_JT_VALUE_OUT_OF_RANGE
---error ER_JSON_TABLE_ERROR_ON_FIELD
+--error ER_JSON_TABLE_SCALAR_EXPECTED
 SELECT * FROM
   JSON_TABLE('[3.14159]',
               '$[*]' COLUMNS (col18 DECIMAL(3,3) PATH '$' ERROR ON ERROR)

sql/handler.cc

@@ -4225,7 +4225,11 @@ void handler::print_error(int error, myf errflag)
         }
       }
       else
+      {
+        if (!temporary)
           my_error(ER_GET_ERRNO, errflag, error, table_type());
+        /* else no error message. */
+      }
       DBUG_VOID_RETURN;
     }
   }

sql/json_table.cc

@@ -23,6 +23,7 @@
 #include "json_table.h"
 #include "sql_show.h"
 
+#define HA_ERR_JSON_TABLE (HA_ERR_LAST+1)
 
 class table_function_handlerton
 {
@@ -104,6 +105,12 @@ class ha_json_table: public handler
     { return NULL; }
   int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info)
     override { return 1; }
+  /* Give no message. */
+  bool get_error_message(int error, String *buf) override
+  {
+    buf->length(0);
+    return TRUE;
+  }
 };
 
 
@@ -284,7 +291,7 @@ int ha_json_table::rnd_next(uchar *buf)
         error code that just doesn't produce extra
         messages.
       */
-      return HA_ERR_TABLE_IN_FK_CHECK;
+      return HA_ERR_JSON_TABLE;
     }
     return HA_ERR_END_OF_FILE;
   }
@@ -297,7 +304,7 @@ int ha_json_table::rnd_next(uchar *buf)
   table->in_use->count_cuted_fields= CHECK_FIELD_EXPRESSION;
   res= fill_column_values(buf, NULL);
   table->in_use->count_cuted_fields= cf_orig;
-  return res ? HA_ERR_TABLE_IN_FK_CHECK : 0;
+  return res ? HA_ERR_JSON_TABLE : 0;
 }
 
 
@@ -401,7 +408,7 @@ int ha_json_table::fill_column_values(uchar * buf, uchar *pos)
         {
           if (not_found)
           {
-            if (jc->m_on_empty.respond(jc, *f))
+            if (jc->m_on_empty.respond(jc, *f, ER_JSON_TABLE_ERROR_ON_FIELD))
               goto error_return;
           }
           else
@@ -409,7 +416,7 @@ int ha_json_table::fill_column_values(uchar * buf, uchar *pos)
             if (!json_value_scalar(&je) ||
                 store_json_in_field(*f, &je))
             {
-              if (jc->m_on_error.respond(jc, *f))
+              if (jc->m_on_error.respond(jc, *f, ER_JSON_TABLE_SCALAR_EXPECTED))
                 goto error_return;
             }
             else
@@ -424,7 +431,7 @@ int ha_json_table::fill_column_values(uchar * buf, uchar *pos)
                    !json_find_path(&je, &jc->m_path, &cur_step,
                                    array_counters)))
               {
-                if (jc->m_on_error.respond(jc, *f))
+                if (jc->m_on_error.respond(jc, *f, ER_JSON_TABLE_MULTIPLE_MATCHES))
                   goto error_return;
               }
             }
@@ -449,7 +456,7 @@ int ha_json_table::fill_column_values(uchar * buf, uchar *pos)
 
 int ha_json_table::rnd_pos(uchar * buf, uchar *pos)
 {
-  return fill_column_values(buf, pos) ? HA_ERR_TABLE_IN_FK_CHECK : 0;
+  return fill_column_values(buf, pos) ? HA_ERR_JSON_TABLE : 0;
 }
 
 
@@ -1024,9 +1031,12 @@ int Json_table_nested_path::set_path(THD *thd, const LEX_CSTRING &path)
   @brief 
     Perform the action of this response on field @f (emit an error, or set @f
     to NULL, or set it to default value).
+    error_num supposed to have the error message with field_name and table_name
+    arguments.
 */
 
-int Json_table_column::On_response::respond(Json_table_column *jc, Field *f)
+int Json_table_column::On_response::respond(Json_table_column *jc, Field *f,
+                                            uint error_num)
 {
   switch (m_response)
   {
@@ -1036,8 +1046,7 @@ int Json_table_column::On_response::respond(Json_table_column *jc, Field *f)
       break;
     case Json_table_column::RESPONSE_ERROR:
       f->set_null();
-      my_error(ER_JSON_TABLE_ERROR_ON_FIELD, MYF(0),
-          f->field_name.str, f->table->alias.ptr());
+      my_error(error_num, MYF(0), f->field_name.str, f->table->alias.ptr());
       return 1;
     case Json_table_column::RESPONSE_DEFAULT:
       f->set_notnull();

sql/json_table.h

@@ -141,7 +141,7 @@ class Json_table_column : public Sql_alloc
   public:
     Json_table_column::enum_on_response m_response;
     LEX_CSTRING m_default;
-    int respond(Json_table_column *jc, Field *f);
+    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; }
   };

sql/share/errmsg-utf8.txt

@@ -7979,3 +7979,7 @@ ER_JSON_TABLE_ERROR_ON_FIELD
         eng "Field '%s' can't be set for JSON_TABLE '%s'."
 ER_JSON_TABLE_ALIAS_REQUIRED
         eng "Every table function must have an alias."
+ER_JSON_TABLE_SCALAR_EXPECTED
+        eng "Can't store an array or an object in the scalar column '%s' of JSON_TABLE '%s'."
+ER_JSON_TABLE_MULTIPLE_MATCHES
+        eng "Can't store multiple matches of the path in the column '%s' of JSON_TABLE '%s'."