IoT Platform provides various functions that can be used in a parser script to process data. The functions can be used to convert data types, forward data to destinations, and process payloads of specific data types. This article describes the available functions.

Convert data types

Function Description
toBoolean(Object) Converts the Object parameter to a Boolean value. The parameter supports the following data types:
  • Boolean: The function returns the same value as the parameter.
  • Number: If the parameter is set to 0, the function returns false. Otherwise, the function returns true.
  • String: If the parameter is set to "true", the function returns true. Otherwise, the function returns false.
  • If the parameter is set to null, the function returns false.
toNumber(Object) Converts the Object parameter to a number. The parameter supports the following data types:
  • Boolean: If the parameter is set to true, the function returns 1. If the parameter is set to false, the function returns 0.
  • Number: The function returns the same value as the parameter.
  • String: The function parses the string to a number.
  • If the parameter is set to null, the function returns 0.
toString(Object) Converts the Object parameter to a string.

If the parameter is set to a value other than null, the function returns the value as a string. If the parameter is set to null, the function returns an empty string.

If the parameter is of the binary type, the function returns a UTF-8 decoded value.

toMap(Object) Converts the Object parameter to a map. The parameter supports the following data types:
  • Map: The function returns the same value as the parameter.
  • String: The function parses the string to a map based on the JSON format.
  • If the parameter is set to null, the function returns an empty map.
toArray(Object) Converts the Object parameter to an array. The parameter supports the following data types:
  • Array: The function returns the same value as the parameter.
  • String: The function parses the string to an array based on the JSON format.
  • If the parameter is set to null, the function returns an empty array.
toBinary(Object) Converts the Object parameter to a binary value. The parameter supports the following data types:
  • Binary: The function returns the same value as the parameter.
  • String: The function returns a UTF-8 encoded value.
  • If the parameter is set to null, the function returns an empty binary value.

Forward data to destinations

In the following functions, the destinationId parameter specifies the ID of a data destination and the payload parameter specifies the message content.

Function Description
writeAmqp(destinationId, payload, tag) Forwards data to an AMQP consumer group.

tag: Optional. If you set a tag, the tag is added to all messages that are forwarded to the AMQP consumer group.

The tag must be 1 to 128 characters in length. You can specify a constant or a variable in the tag.
  • The constant can contain letters and digits.
  • The variable indicates the value of a key in the JSON data that are parsed from payloads by using a script. If the value is unavailable, a tag is not added to the messages.
writeFc(destinationId, data) Forwards data to Function Compute.

data: the data that is forwarded to Function Compute.

writeKafka(destinationId, payload, key) Forwards data to Message Queue for Apache Kafka.

key: Optional. The key that is included in the message forwarded to Message Queue for Apache Kafka.

You can route messages based on tags on your consumer client.

writeMns(destinationId, payload) Forwards data to Message Service (MNS).
writeTableStore(destinationId, data) Forwards data to Tablestore.

data: the data that is written to Tablestore. Only the map data type is supported. The key indicates the table column name, and the value indicates the column value.

The data parameter must contain the primary key of Tablestore.

writeRds(destinationId, data) Forwards data to ApsaraDB RDS.

data: the data that is written to ApsaraDB RDS. Only the map data type is supported. The key indicates the table column name, and the value indicates the column value.

writeIotTopic(destinationId, topic, payload) Forwards data to another topic.

Topic: the topic to which the data is forwarded. The ProductKey in the topic must be the same as the ProductKey that is specified when you set the data destination.

Process payloads of specific data types

  • Map
    Function Description
    [Object] Retrieves the value of a specified key.
    size() Retrieves the number of key-value pairs in a map.
    containKey(String) Checks whether a map contains a specified key.
    keySet() Retrieves keys in a map. An array is returned.
    remove(Object) Removes a key-value pair in a map based on a specified key.
    put(Object, Object) Adds key-value pairs to a map.
    putAll(map) Adds another map to a map.
  • Array
    Function Description
    [int] Retrieves the value at a specified index. The index of the first element in an array is 0.
    contains(Object) Checks whether an array contains a specified element.
    remove(Object) Removes a specified element from an array.
    removeAt(int) Removes an element at a specified index in an array.
    add(Object) Adds an element to the end of an array.
    add(index, Object) Adds an element to a specified index.
    addAll(array) Adds another array to an array.
    size() Retrieves the number of elements in an array.
  • String
    Function Description
    substring(start, end) Extracts a string from the start position to the end-1 position. If you do not specify the end parameter, the extraction continues until the end of the string.
    length() Queries the length of a string.
    split(String) Splits a string by using a specified separator.
    startWith(String) Checks whether a string starts with a specified substring.
    endWith(String) Checks whether a string ends with a specified substring.
    indexOf(String, index) Queries the position where a substring first appears from a specified index of a string.

    The default value of the index parameter is 0.

Other functions

Function Description
endWith(input, suffix) Checks whether the input string ends with a specified suffix.

A Boolean value is returned.

getDeviceTag(key) Returns the device tag value of a tag key. If the tag with the specified key is not attached to a device, no tag value is returned.

The functions that are supported by Data Forwarding v1.0 can be used in parser scripts of Data Forwarding v2.0. For more information, see Functions supported by the data forwarding feature.