docs/en/sql-reference/sql-functions/json-functions/json-query-and-processing-functions/to_json.md
Converts a Map or Struct value into a JSON string. If the input value is NULL, NULL is returned.
:::tip All of the JSON functions and operators are listed in the navigation and on the overview page
Accelerate your queries with generated columns :::
If you want to cast values of other data types, see cast.
This function is supported from v3.1 onwards.
to_json(any_value)
any_value: the Map or Struct expression you want to convert. If the input value is invalid, an error is returned. The value in each key-value pair of the Map or Struct value is nullable. See the last example.
Returns a JSON value.
select to_json(map{1:'a',2:'b'});
+---------------------------+
| to_json(map{1:'a',2:'b'}) |
+---------------------------+
| {"1": "a", "2": "b"} |
+---------------------------+
select to_json(row('asia','eu'));
+--------------------------------+
| to_json(row('asia', 'eu')) |
+--------------------------------+
| {"col1": "asia", "col2": "eu"} |
+--------------------------------+
select to_json(map('a', named_struct('b', 1)));
+----------------------------------------+
| to_json(map{'a':named_struct('b', 1)}) |
+----------------------------------------+
| {"a": {"b": 1}} |
+----------------------------------------+
select to_json(named_struct("k1", cast(null as string), "k2", "v2"));
+-----------------------------------------------------------------------+
| to_json(named_struct('k1', CAST(NULL AS VARCHAR(65533)), 'k2', 'v2')) |
+-----------------------------------------------------------------------+
| {"k1": null, "k2": "v2"} |
+-----------------------------------------------------------------------+