getDouble (Function)

Function retrieves the double value specified in the given path of the JSON element.

Syntax

<DOUBLE> json:getDouble(<STRING|OBJECT> json, <STRING> path)

Query Parameters

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
json	The JSON input containing double value.		STRING OBJECT	No	Yes
path	The JSON path to fetch the double value.		STRING	No	Yes

Example 1

@info(name = 'query1')
json:getDouble(json,'$.salary')

The json:getDouble(json,'$.salary') function searches the json object for a floating-point (double) value associated with the key salary. Given a JSON object like {'name' : 'John', 'salary' : 12000.0}, it would return 12000.0 as there is a matching double value at $.salary.

Example 2

@info(name = 'query1')
json:getDouble(json,'$.salary')

The json:getDouble(json,'$.salary') function attempts to find a double value in the json object at the path $.salary. However, if no value exists at this location, or if the value is not a double, the function returns null. For example, given a JSON object like {'name' : 'John', 'age' : 23}, it would return null as there is no salary key in the JSON object.

Example 3

@info(name = 'query1')
json:getDouble(json,'$.name')

The json:getDouble(json,'$.name') function searches the json object for a double value associated with the key name. If there is no matching double value at $.name, or if the value isn't a double, the function will return null. For instance, given a JSON object like {'name' : 'John', 'age' : 23}, this function would return null because the value at $.name is a string, not a double.

Example 4

CREATE STREAM EmployeeStream (json string);
CREATE SINK STREAM SalaryStream (name string, salary double);

@info(name = 'ExtractSalary')
INSERT INTO SalaryStream
SELECT json:getString(json, '$.name') AS name, json:getDouble(json, '$.salary') AS salary
FROM EmployeeStream WINDOW TUMBLING_LENGTH(1);

In this example, an EmployeeStream is created to receive JSON strings, each representing an employee's details. The SalaryStream is created to output the extracted name and salary data.

The ExtractSalary query listens for events on EmployeeStream. For each event, the query uses json:getString(json, '$.name') and json:getDouble(json, '$.salary') to extract the name (as a string) and salary (as a double) from the JSON string. These extracted values are then inserted into the SalaryStream.