| --- | |
| { | |
| "title": "JSON_EACH_OUTER", | |
| "language": "en", | |
| "description": "Expands the top-level JSON object into a set of key/value pairs, where the value column retains JSON type. Unlike json_each, returns one row of NULLs instead of 0 rows when input is NULL or an empty object. Must be used with LATERAL VIEW." | |
| } | |
| --- | |
| ## Description | |
| The `json_each_outer` table function expands the top-level JSON object into a set of key/value pairs. Each row contains one key (`key`) and its corresponding value (`value`). The `value` column retains the JSON type, so string values are returned with JSON quotes preserved. | |
| Unlike [`json_each`](json-each.md), when the input is NULL or an empty object, `json_each_outer` returns one row of `NULL, NULL` instead of 0 rows. | |
| Must be used with [`LATERAL VIEW`](../../../query-data/lateral-view.md). | |
| ## Syntax | |
| ```sql | |
| JSON_EACH_OUTER(<json_str>) | |
| ``` | |
| ## Parameters | |
| | Parameter | Description | | |
| | ------------ | ------------------------------------------------------------- | | |
| | `<json_str>` | The JSON string to expand. The content must be a JSON object. | | |
| ## Return Value | |
| Returns multi-column, multi-row data. Each row corresponds to one key-value pair in the JSON object: | |
| | Column | Type | Description | | |
| | ------- | ------ | --------------------------------------------------------------------------------------- | | |
| | `key` | String | The key name from the JSON object | | |
| | `value` | JSON | The corresponding value, kept as JSON type (string values include quotes, e.g. `"foo"`) | | |
| Special cases: | |
| - If `<json_str>` is NULL, returns 1 row of `NULL, NULL` | |
| - If `<json_str>` is an empty object (`{}`), returns 1 row of `NULL, NULL` | |
| ## Examples | |
| Basic usage: expand a JSON object with string values | |
| ```sql | |
| SELECT k, v | |
| FROM (SELECT 1) dummy | |
| LATERAL VIEW json_each_outer('{"a":"foo","b":"bar"}') t AS k, v; | |
| ``` | |
| ```text | |
| +---+-------+ | |
| | k | v | | |
| +---+-------+ | |
| | a | "foo" | | |
| | b | "bar" | | |
| +---+-------+ | |
| ``` | |
| NULL parameter: returns 1 row of NULL | |
| ```sql | |
| SELECT k, v | |
| FROM (SELECT 1) dummy | |
| LATERAL VIEW json_each_outer(NULL) t AS k, v; | |
| ``` | |
| ```text | |
| +------+------+ | |
| | k | v | | |
| +------+------+ | |
| | NULL | NULL | | |
| +------+------+ | |
| ``` | |
| Empty object: returns 1 row of NULL | |
| ```sql | |
| SELECT k, v | |
| FROM (SELECT 1) dummy | |
| LATERAL VIEW json_each_outer('{}') t AS k, v; | |
| ``` | |
| ```text | |
| +------+------+ | |
| | k | v | | |
| +------+------+ | |
| | NULL | NULL | | |
| +------+------+ | |
| ``` |