setElement (Function)

Function sets JSON element into a given JSON at the specific path.

Syntax

<OBJECT> json:setElement(<STRING|OBJECT> json, <STRING> path, <STRING|BOOL|DOUBLE|FLOAT|INT|LONG|OBJECT> json.element)
<OBJECT> json:setElement(<STRING|OBJECT> json, <STRING> path, <STRING|BOOL|DOUBLE|FLOAT|INT|LONG|OBJECT> json.element, <STRING> key)

Query Parameters

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
json	The JSON to which a JSON element needs to be added/replaced.		STRING OBJECT	No	Yes
path	The JSON path where the JSON element should be added/replaced.		STRING	No	Yes
json.element	The JSON element being added.		STRING BOOL DOUBLE FLOAT INT LONG OBJECT	No	Yes
key	The key to be used to refer the newly added element in the input JSON.	Assumes the element is added to a JSON array, or the element selected by the JSON path will be updated.	STRING	Yes	Yes

Example 1

json:setElement(json, '$', "{'country' : 'USA'}", 'address')

The json:setElement function in this example is used to add a new element to the input JSON. Here, it adds the address element with the value {'country' : 'USA'} at the root of the JSON ($).

For instance, if the input json is {'name' : 'John', 'married' : true}, the function modifies the JSON to include the new address element, resulting in {'name' : 'John', 'married' : true, 'address' : {'country' : 'USA'}}.

Example 2

json:setElement(json, '$', 40, 'age')

The json:setElement function in this example is used to add a new age element with the value 40 to the root of the input JSON ($).

If the input json is {'name' : 'John', 'married' : true}, the function updates the JSON to {'name' : 'John', 'married' : true, 'age' : 40}.

Example 3

json:setElement(json, '$', 45, 'age')

The json:setElement function here modifies an existing age element in the input JSON, updating its value to 45 at the root level ($).

If the input json is {'name' : 'John', 'married' : true, 'age' : 40}, the function updates the JSON to {'name' : 'John', 'married' : true, 'age' : 45}.

Example 4

json:setElement(json, '$.items', 'book')

In this example, json:setElement is used to modify an existing items array in the input JSON, adding a new value 'book' to it.

For example, if the input json is {'name' : 'Stationary', 'items' : ['pen', 'pencil']}, the function adds book to the items array, updating the JSON to {'name' : 'Stationary', 'items' : ['pen', 'pencil', 'book']}.

Example 5

json:setElement(json, '$.address', 'city', 'SF')

The json:setElement function in this example is used to modify an existing element in the input JSON. Here, it attempts to update the city element within the address object.

However, if the input json is {'name' : 'John', 'married' : true}, the function will not modify the JSON, because there is no valid path for $.address. Therefore, it returns the original JSON unmodified.

Example 6

CREATE STREAM PersonStream (json string);
CREATE SINK STREAM UpdatedPersonStream (json object);

@info(name = 'AddAddressDetails')
INSERT INTO UpdatedPersonStream
SELECT json:setElement(json, '$', "{'city' : 'SF', 'country' : 'USA'}", 'address') AS json
FROM PersonStream;

In this stream worker, two streams are defined: PersonStream for the incoming data, and UpdatedPersonStream for the outgoing data.

The AddAddressDetails query is designed to process events from the PersonStream. Each event is a JSON string that contains information about a person.

The function json:setElement(json, '$', "{'city' : 'SF', 'country' : 'USA'}", 'address') is used within the query to add or modify an address object at the root of each JSON string. This address object includes a city and country.

The resulting updated JSON string, which now includes an address, is inserted into the UpdatedPersonStream.

In operation, this query continuously processes each person's details from PersonStream, adds or updates the address, and outputs the updated JSON strings into UpdatedPersonStream. This enables the real-time enhancement of person details within the incoming data stream.