Map Extension

This extension provides the capability to send a map object inside Siddhi stream definitions and use it inside queries. The following are the functions of the map extension.

Create function

Syntax	`<Object> map:create()` or `<Object> map:create(<Object> key1, <Object> value1,<Object> key2, <Object> value2,...<Object> keyN, <Object> valueN)`
Extension Type	Function
Description	Returns the created map object.
Examples	`create()` returns an empty map. `create(1 , ”one” , 2 , ”two” , 3 , ”three”)` returns a map with keys `1, 2, 3` and corresponding values `"one", "two", "three"`.

Get function

Syntax	`<Object> map:get(<Map> map, <Object> key)`
Extension Type	Function
Description	Returns the value object from the map that is related to the given key.
Example	`get(company,1)` returns the value that is related to the key `1` from the map named `company`.

Is Map function

Syntax	`<bool> map:isMap(<Object> object)`
Extension Type	Function
Description	Returns `true` if the object is a map or `false` otherwise.
Example	`isMap(students)` returns `true` if the students object is a map. It returns `false` if the `students` object is not a map.

Put function

Syntax	`<Object> map:put(<Object> map, <Object> key,<Object> value)`
Extension Type	Function
Description	Returns the updated map after adding the given key-value pair.
Example	`put(students , 1234 , ”sam”)` returns the updated map named `students` after adding the object `"sam"` with key `1234`.

Remove function

Syntax	`<Object> map:remove(<Object> map, <Object> key)`
Extension Type	Function
Description	Returns the updated map after removing the element with key.
Example	`remove(students , 1234)` returns the updated map `students` after removing the element with the key `1234`.

Create from JSON function

Syntax	`<Object> map:createFromJSON(<string> JSONstring)`
Extension Type	Function
Description	Returns the map created with the key values pairs given in the `JSONstring`.
Example	`createFromJSON(“{‘symbol' : 'IBM' , 'price' : 200, 'volume' : 100}”)` returns a map with the keys "`symbol"`, `"price", "volume"`, and with the values `"IBM"`, `200` and `100` respectively.

Create from XML function

Syntax	`<Object> map:createFromXML(<string> XMLstring)`
Extension Type	Function
Description	Returns the map created with the key values pairs given in the XMLstring.
Example	`createFromXML(“<company> <symbol> wso2 </symbol> <price> <100> </price> <volume> 200 </volume> </company>”)` returns a map with the keys `"symbol"`, `"price"`, `"volume"`, and with the values `WSO2`, `100` and `200` respectively.

To JSON function

Syntax	`<String> map:toJSON(<Object> map)`
Extension Type	Function
Description	Converts a map into a JSON object and returns the definition of that JSON object as a string.
Example	If `"company"` is a map with key value pairs `("symbol" : wso2)`, `("volume" : 100)`, and `("price",200)`, `toJSON(company)` returns the string `“{“symbol” : “wso2” , “volume” : 100 , “price” : 200}”`.

To XML function

Syntax	`<String> map:toXML(<Object> map)` or `<String> map:toXML(<Object> map, <String> rootElementName)`
Extension Type	Function
Description	Returns the map as an XML string.
Example	If `"company"` is a map with key value pairs `(“symbol” : wso2)`, `(“volume” : 100)`, and `(“price” : 200),` `toXML(company)` returns the string `“<symbol>wso2</symbol><volume><100></volume><price>200</price>"`. `toXML(company, "abcCompany")` returns the string `“<abcCompany><symbol>wso2</symbol><volume><100></volume><price>200</price></abcCompany>"`.