JSON_EXISTS - MaxCompute - Alibaba Cloud Documentation Center

Checks whether the JSON value in a specific JSON path exist.

Syntax

boolean json_exists(<json>, <json_path>)

Parameters

json: required. This parameter specifies the JSON expression that you want to process.
json_path: required. This parameter specifies the JSON path in which a specific JSON value is checked.

Note

If the JSON path that you specify is invalid, an error is reported. In strict mode, if the structure of JSON data in a JSON path is inconsistent with the actual structure of JSON data, no error is reported, and the JSON_EXISTS function returns false.

Return value

The return value is true or false, which is of the BOOLEAN type.

Examples

Example 1: Check whether the value of the key a exists in a JSON object.
```
select json_exists(json '{"a":1, "b":2}', '$.a');
```
The following result is returned:
```
+------+
| _c0  |
+------+
| true |
+------+
```
Example 2: Check whether the value of the key c exists in a JSON object.
```
select json_exists(json '[1,2, {"a":34}]', '$[2].a');
```
The following result is returned:
```
+------+
| _c0  |
+------+
| true |
+------+
```
Example 3: Check whether values that are obtained based on a specific subscript exist.
```
select json_exists(json '{"a":1, "b":2}', 'strict $.c');
```
The following result is returned:
```
+------+
| _c0  |
+------+
| false |
+------+
```

Related functions

JSON_EXISTS is a complex type function. For more information about the functions that are used to process data of complex data types, such as ARRAY, MAP, STRUCT, and JSON, see Complex type functions.