README.md

kafka-connect-jsonpath-accessor

A library enables to access Kafka connect data with Json Path expression. You can access Kafka connect data using expressions such as JSON Path $.name.

This library is intended to help data manipulation in Kafka connect and SMT application. The currently supported connect data types are org.apache.kafka.connect.data.Struct and Map<String, Object>.

Getting started

Select latest version from the maven repository.

Usage

Example Code

        // This example retrieves and updates values in Map<String, Object>
        // The library also supports org.apache.kafka.connect.data.Struct.
        HashMap<String, Object> data = new HashMap<>();
        data.put("users", Arrays.asList(
                new HashMap<String, Object>() {{
                    put("name", "Fifer");
                }},
                new HashMap<String, Object>() {{
                    put("name", "Fiddler");
                }},
                new HashMap<String, Object>() {{
                    put("name", "Practical Guy");
                }}
        ));

        // Getter/Updater instance is stateless. You can call `run` against different data
        MapAccessor.Getter getter = new MapAccessor.Getter("$.users[*].name");

        Map<String, Object> values = getter.run(data);
        values.forEach((k, v) -> System.out.println((k + ":" + v)));
        // Getter.run() returns the pairs of the json path and value.
        // $.users[0].name:Fifer
        // $.users[1].name:Fiddler
        // $.users[2].name:Practical Guy

        MapAccessor.Updater updater = new MapAccessor.Updater("$.users[*].name");

        // If you want to change the value for each path individually, you can pass the json path and the pair of values to be updated.
        // This interface is useful for re-writing the individually transformed values for the results obtained using Getter,
        // because Getter.run() returns the pairs of json path and original value.
        Map<String, Object> updated = updater.run(data, new HashMap<String, Object>() {{
            put("$.users[0].name", "Ultimate Guy");
            put("$.users[1].name", "Incredible Guy");
        }});
        System.out.println(updated);
        // {users=[{name=Ultimate Guy}, {name=Incredible Guy}, {name=Practical Guy}]}

        // Or if you want to simply update all values matched with the json path to the same value, you can do like this:
        updated = updater.run(data, "Wolf!");
        System.out.println(updated);
        // {users=[{name=Wolf!}, {name=Wolf!}, {name=Wolf!}]}

Class	Kafka Connect Type
io.github.rerorero.kafka.jsonpath.StructAccessor.Getter/Updater	org.apache.kafka.connect.data.Struct
io.github.rerorero.kafka.jsonpath.MapAccessor.Getter/Updater	Map<String, Object>

Json Path Expressions

Only some expressions are supported, as follows:

Operator	Description
$	The root element. All JsonPath string has to be started with this operator.
*	Wildcard. Only supported for use as an array index.
.<name>	Dot-notated child.
['name']	Bracket-notated child. Multiple names are not supported.
[<number>]	Array index. Multiple indices are not supported.