putAll (Function)
Function returns the updated map after adding all the key-value pairs from another map. If there are duplicate keys, the key will be assigned new values from the map that's being copied.
Syntax
<OBJECT> map:putAll(<OBJECT> to.map, <OBJECT> from.map)
Query Parameters
| Name | Description | Default Value | Possible Data Types | Optional | Dynamic |
|---|---|---|---|---|---|
| to.map | The map into which the key-values need to copied. | OBJECT | No | Yes | |
| from.map | The map from which the key-values are copied. | OBJECT | No | Yes |
Example 1
map:putAll(toMap, fromMap)
In this example, the map:putAll(toMap, fromMap) function is used to merge two maps, toMap and fromMap. It adds all the key-value pairs from fromMap into toMap. If a key already exists in toMap that is also in fromMap, then the value in toMap for that key is replaced by the value from fromMap.
For instance, if toMap contains key-value pairs (symbol: gdn) and (volume: 100), and fromMap contains key-value pairs (symbol: IBM) and (price : 12), after the function execution, the updated toMap will consist of key-value pairs (symbol: IBM), (price : 12), and (volume :100).
Example 2
CREATE STREAM StockInput (symbol string, price float, volume int, currentDetails object);
CREATE SINK STREAM MergedStockDetails (mergedDetails object);
@info(name = 'MergeStockDetails')
INSERT INTO MergedStockDetails
SELECT map:putAll(currentDetails, map:create(symbol, price, 'volume', volume)) AS mergedDetails
FROM StockInput;
The MergeStockDetails query uses the map:putAll(currentDetails, map:create(symbol, price, 'volume', volume)) function to merge the incoming stock details with the existing currentDetails map. If a stock symbol already exists in currentDetails, its price and volume are updated.
The resulting map is then inserted into the MergedStockDetails stream. This way, the currentDetails map keeps updating with every incoming stock detail from the StockInput stream.
This stream worker assumes that you provide an initial map as an input in the StockInput stream. If you want to start with an empty map, then you'll need to use a function that allows creating an empty map or check for null and create an empty map before using map:putAll().