MDEV-11439 No data type JSON, but CAST(something AS JSON) pretends to work

Use JSON_COMPACT(X) instead of CAST(X AS JSON).
Bonus - X is validated to be a valid JSON.
Fix a typo in the error message.

mysql-test/r/func_json.result

@@ -402,14 +402,14 @@ json_object("a", json_object("b", "abcd"))
 select json_object("a", '{"b": "abcd"}');
 json_object("a", '{"b": "abcd"}')
 {"a": "{\"b\": \"abcd\"}"}
-select json_object("a", cast('{"b": "abcd"}' as json));
-json_object("a", cast('{"b": "abcd"}' as json))
+select json_object("a", json_compact('{"b": "abcd"}'));
+json_object("a", json_compact('{"b": "abcd"}'))
 {"a": {"b": "abcd"}}
-select cast(NULL AS JSON);
-cast(NULL AS JSON)
+select json_compact(NULL);
+json_compact(NULL)
 NULL
-select json_depth(cast(NULL as JSON));
-json_depth(cast(NULL as JSON))
+select json_depth(json_compact(NULL));
+json_depth(json_compact(NULL))
 NULL
 select json_depth('[[], {}]');
 json_depth('[[], {}]')

mysql-test/t/func_json.test

@@ -161,10 +161,10 @@ select json_unquote('abc');
 
 select json_object("a", json_object("b", "abcd"));
 select json_object("a", '{"b": "abcd"}');
-select json_object("a", cast('{"b": "abcd"}' as json));
+select json_object("a", json_compact('{"b": "abcd"}'));
 
-select cast(NULL AS JSON);
-select json_depth(cast(NULL as JSON));
+select json_compact(NULL);
+select json_depth(json_compact(NULL));
 select json_depth('[[], {}]');
 select json_depth('[[[1,2,3],"s"], {}, []]');
 select json_depth('[10, {"a": 20}]');

sql/item.h

@@ -1095,6 +1095,8 @@ class Item: public Value_source,
     Returns the val_str() value converted to the given character set.
   */
   String *val_str(String *str, String *converter, CHARSET_INFO *to);
+
+  virtual String *val_json(String *str) { return val_str(str); }
   /*
     Return decimal representation of item with fixed point.
 

sql/item_create.cc

@@ -7228,9 +7228,6 @@ create_func_cast(THD *thd, Item *a, Cast_target cast_type,
     res= new (thd->mem_root) Item_char_typecast(thd, a, len, real_cs);
     break;
   }
-  case ITEM_CAST_JSON:
-    res= new (thd->mem_root) Item_json_typecast(thd, a);
-    break;
   default:
   {
     DBUG_ASSERT(0);

sql/item_func.h

@@ -2221,7 +2221,7 @@ enum Cast_target
 {
   ITEM_CAST_BINARY, ITEM_CAST_SIGNED_INT, ITEM_CAST_UNSIGNED_INT,
   ITEM_CAST_DATE, ITEM_CAST_TIME, ITEM_CAST_DATETIME, ITEM_CAST_CHAR,
-  ITEM_CAST_DECIMAL, ITEM_CAST_DOUBLE, ITEM_CAST_JSON
+  ITEM_CAST_DECIMAL, ITEM_CAST_DOUBLE
 };
 
 

sql/item_jsonfunc.cc

@@ -373,7 +373,7 @@ static int path_setup_nwc(json_path_t *p, CHARSET_INFO *i_cs,
 
 longlong Item_func_json_valid::val_int()
 {
-  String *js= args[0]->val_str(&tmp_value);
+  String *js= args[0]->val_json(&tmp_value);
   json_engine_t je;
 
   if ((null_value= args[0]->null_value))
@@ -401,7 +401,7 @@ longlong Item_func_json_exists::val_int()
   json_engine_t je;
   uint array_counters[JSON_DEPTH_LIMIT];
 
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
 
   if (!path.parsed)
   {
@@ -454,7 +454,7 @@ void Item_func_json_value::fix_length_and_dec()
 String *Item_func_json_value::val_str(String *str)
 {
   json_engine_t je;
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   int error= 0;
   uint array_counters[JSON_DEPTH_LIMIT];
 
@@ -587,7 +587,7 @@ void Item_func_json_unquote::fix_length_and_dec()
 
 String *Item_func_json_unquote::val_str(String *str)
 {
-  String *js= args[0]->val_str(&tmp_s);
+  String *js= args[0]->val_json(&tmp_s);
   json_engine_t je;
   int c_len;
 
@@ -712,7 +712,7 @@ static bool path_ok(const json_path_with_flags *paths_list, int n_paths,
 
 String *Item_func_json_extract::val_str(String *str)
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je, sav_je;
   json_path_t p;
   const uchar *value;
@@ -817,7 +817,7 @@ String *Item_func_json_extract::val_str(String *str)
 
 longlong Item_func_json_extract::val_int()
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je;
   uint n_arg;
   uint array_counters[JSON_DEPTH_LIMIT];
@@ -1040,7 +1040,7 @@ static int check_contains(json_engine_t *js, json_engine_t *value)
 
 longlong Item_func_json_contains::val_int()
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je, ve;
   int result;
 
@@ -1049,7 +1049,7 @@ longlong Item_func_json_contains::val_int()
 
   if (!a2_parsed)
   {
-    val= args[1]->val_str(&tmp_val);
+    val= args[1]->val_json(&tmp_val);
     a2_parsed= a2_constant;
   }
 
@@ -1179,7 +1179,7 @@ static int parse_one_or_all(const Item_func *f, Item *ooa_arg,
 #ifdef DUMMY
 longlong Item_func_json_contains_path::val_int()
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je;
   uint n_arg;
   longlong result;
@@ -1247,7 +1247,7 @@ longlong Item_func_json_contains_path::val_int()
 
 longlong Item_func_json_contains_path::val_int()
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je;
   uint n_arg;
   longlong result;
@@ -1351,7 +1351,7 @@ static int append_json_value(String *str, Item *item, String *tmp_val)
     return str->append(t_f, t_f_len);
   }
   {
-    String *sv= item->val_str(tmp_val);
+    String *sv= item->val_json(tmp_val);
     if (item->null_value)
       goto append_null;
     if (item->is_json_type())
@@ -1461,7 +1461,7 @@ void Item_func_json_array_append::fix_length_and_dec()
 String *Item_func_json_array_append::val_str(String *str)
 {
   json_engine_t je;
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   uint n_arg, n_path, str_rest_len;
   const uchar *ar_end;
 
@@ -1588,7 +1588,7 @@ String *Item_func_json_array_append::val_str(String *str)
 String *Item_func_json_array_insert::val_str(String *str)
 {
   json_engine_t je;
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   uint n_arg, n_path;
 
   DBUG_ASSERT(fixed == 1);
@@ -1959,7 +1959,7 @@ String *Item_func_json_merge::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
   json_engine_t je1, je2;
-  String *js1= args[0]->val_str(&tmp_js1), *js2;
+  String *js1= args[0]->val_json(&tmp_js1), *js2;
   uint n_arg;
 
   if (args[0]->null_value)
@@ -1970,7 +1970,7 @@ String *Item_func_json_merge::val_str(String *str)
     str->set_charset(js1->charset());
     str->length(0);
 
-    js2= args[n_arg]->val_str(&tmp_js2);
+    js2= args[n_arg]->val_json(&tmp_js2);
     if (args[n_arg]->null_value)
       goto null_return;
 
@@ -2028,7 +2028,7 @@ void Item_func_json_length::fix_length_and_dec()
 
 longlong Item_func_json_length::val_int()
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je;
   uint length= 0;
   uint array_counters[JSON_DEPTH_LIMIT];
@@ -2105,7 +2105,7 @@ longlong Item_func_json_length::val_int()
 
 longlong Item_func_json_depth::val_int()
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je;
   uint depth= 0, c_depth= 0;
   bool inc_depth= TRUE;
@@ -2164,7 +2164,7 @@ void Item_func_json_type::fix_length_and_dec()
 
 String *Item_func_json_type::val_str(String *str)
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je;
   const char *type;
 
@@ -2232,7 +2232,7 @@ void Item_func_json_insert::fix_length_and_dec()
 String *Item_func_json_insert::val_str(String *str)
 {
   json_engine_t je;
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   uint n_arg, n_path;
   json_string_t key_name;
 
@@ -2478,7 +2478,7 @@ void Item_func_json_remove::fix_length_and_dec()
 String *Item_func_json_remove::val_str(String *str)
 {
   json_engine_t je;
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   uint n_arg, n_path;
   json_string_t key_name;
 
@@ -2661,7 +2661,7 @@ void Item_func_json_keys::fix_length_and_dec()
 String *Item_func_json_keys::val_str(String *str)
 {
   json_engine_t je;
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   uint n_keys= 0;
   uint array_counters[JSON_DEPTH_LIMIT];
 
@@ -2837,7 +2837,7 @@ static int append_json_path(String *str, const json_path_t *p)
 
 String *Item_func_json_search::val_str(String *str)
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   String *s_str= args[2]->val_str(&tmp_js);
   json_engine_t je;
   json_path_t p, sav_path;
@@ -2934,21 +2934,6 @@ String *Item_func_json_search::val_str(String *str)
 }
 
 
-void Item_json_typecast::fix_length_and_dec()
-{
-  maybe_null= args[0]->maybe_null;
-  max_length= args[0]->max_length;
-}
-
-
-String *Item_json_typecast::val_str(String *str)
-{
-  String *vs= args[0]->val_str(str);
-  null_value= args[0]->null_value;
-  return vs;
-}
-
-
 const char *Item_func_json_format::func_name() const
 {
   switch (fmt)
@@ -2976,7 +2961,7 @@ void Item_func_json_format::fix_length_and_dec()
 
 String *Item_func_json_format::val_str(String *str)
 {
-  String *js= args[0]->val_str(&tmp_js);
+  String *js= args[0]->val_json(&tmp_js);
   json_engine_t je;
   int tab_size= 4;
 
@@ -3016,3 +3001,12 @@ String *Item_func_json_format::val_str(String *str)
 }
 
 
+String *Item_func_json_format::val_json(String *str)
+{
+  String *js= args[0]->val_json(&tmp_js);
+  if ((null_value= args[0]->null_value))
+    return 0;
+  return js;
+}
+
+

sql/item_jsonfunc.h

@@ -414,19 +414,6 @@ class Item_func_json_search: public Item_json_str_multipath
 };
 
 
-class Item_json_typecast: public Item_str_func
-{
-public:
-  Item_json_typecast(THD *thd, Item *a): Item_str_func(thd, a) {}
-  const char *func_name() const { return "cast_as_json"; }
-  bool is_json_type() { return true; }
-  void fix_length_and_dec();
-  String *val_str(String *str);
-  Item *get_copy(THD *thd, MEM_ROOT *mem_root)
-  { return get_item_copy<Item_json_typecast>(thd, mem_root, this); }
-};
-
-
 class Item_func_json_format: public Item_str_func
 {
 public:
@@ -449,6 +436,8 @@ class Item_func_json_format: public Item_str_func
   const char *func_name() const;
   void fix_length_and_dec();
   String *val_str(String *str);
+  String *val_json(String *str);
+  bool is_json_type() { return true; }
   Item *get_copy(THD *thd, MEM_ROOT *mem_root)
   { return get_item_copy<Item_func_json_format>(thd, mem_root, this); }
 };

sql/share/errmsg-utf8.txt

@@ -7417,7 +7417,7 @@ ER_BINLOG_UNCOMPRESS_ERROR
 ER_JSON_BAD_CHR
         eng "Broken JSON string in argument %d to function '%s' at position %d"
 ER_JSON_NOT_JSON_CHR
-        eng "Character disallowd in JSON in argument %d to function '%s' at position %d"
+        eng "Character disallowed in JSON in argument %d to function '%s' at position %d"
 ER_JSON_EOS
         eng "Unexpected end of JSON text in argument %d to function '%s'"
 ER_JSON_SYNTAX

sql/sql_yacc.yy

@@ -10714,7 +10714,6 @@ cast_type:
           }
         | cast_type_numeric  { $$= $1; Lex->charset= NULL; }
         | cast_type_temporal { $$= $1; Lex->charset= NULL; }
-        | JSON_SYM           { $$.set(ITEM_CAST_JSON); }
         ;
 
 cast_type_numeric: