| --- | |
| { | |
| "title": "JSON_EACH", | |
| "language": "en", | |
| "description": "Expands the top-level JSON object into a set of key/value pairs, where the value column retains JSON type. Must be used with LATERAL VIEW." | |
| } | |
| --- | |
| ## Description | |
| The `json_each` 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. | |
| Must be used with [`LATERAL VIEW`](../../../query-data/lateral-view.md). | |
| ## Syntax | |
| ```sql | |
| JSON_EACH(<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 0 rows | |
| - If `<json_str>` is an empty object (`{}`), returns 0 rows | |
| ## Examples | |
| Basic usage: expand a JSON object with string values | |
| ```sql | |
| SELECT k, v | |
| FROM (SELECT 1) dummy | |
| LATERAL VIEW json_each('{"a":"foo","b":"bar"}') t AS k, v; | |
| ``` | |
| ```text | |
| +---+-------+ | |
| | k | v | | |
| +---+-------+ | |
| | a | "foo" | | |
| | b | "bar" | | |
| +---+-------+ | |
| ``` | |
| > The `value` column is of JSON type, so string values retain their JSON quotes. | |
| JSON object with multiple value types | |
| ```sql | |
| SELECT k, v | |
| FROM (SELECT 1) dummy | |
| LATERAL VIEW json_each('{"str":"hello","num":42,"bool":true,"null_val":null,"arr":[1,2]}') t AS k, v; | |
| ``` | |
| ```text | |
| +----------+---------+ | |
| | k | v | | |
| +----------+---------+ | |
| | str | "hello" | | |
| | num | 42 | | |
| | bool | true | | |
| | null_val | NULL | | |
| | arr | [1,2] | | |
| +----------+---------+ | |
| ``` | |
| NULL parameter: returns 0 rows | |
| ```sql | |
| SELECT k, v | |
| FROM (SELECT 1) dummy | |
| LATERAL VIEW json_each(NULL) t AS k, v; | |
| -- Empty set | |
| ``` | |
| Empty object: returns 0 rows | |
| ```sql | |
| SELECT k, v | |
| FROM (SELECT 1) dummy | |
| LATERAL VIEW json_each('{}') t AS k, v; | |
| -- Empty set | |
| ``` |