SnakeYaml example file

SnakeYaml.java

import org.yaml.snakeyaml.Yaml;
import org.yaml.snakeyaml.constructor.Constructor;
import org.yaml.snakeyaml.nodes.MappingNode;
import org.yaml.snakeyaml.nodes.NodeId;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;


class Node {
    public String name;
}

class Nodes  {
    public List<Node> nodes;
}

class Master {
    public Nodes nodes;
}

class MyDsl {
    public Master master;
}

class MyConstructor extends Constructor {
    MyConstructor() {
        yamlClassConstructors.put(NodeId.mapping, new NodesConstructor());
    }

    class NodesConstructor extends Constructor.ConstructMapping {
        @Override
        protected Object constructJavaBean2ndStep(MappingNode node, Object object) {
            Class type = node.getType();

            if (type.equals(Master.class)) {
                Nodes nodes = new Nodes();
                //FIXME: I don't want to construct the whole object tree here, I only want to fill the nodes
                nodes.nodes = new ArrayList<>();
                Master master = new Master();
                master.nodes = nodes;
                return master;
            } else {
                return super.constructJavaBean2ndStep(node, object);
            }
        }
    }
}

public class SnakeYaml {
    public static void main(String[] args) throws IOException {
        // 1: this is working OK
        Yaml yaml = new Yaml();
        MyDsl myDsl = yaml.loadAs("master:\n  nodes:\n    nodes:\n      - name: mystage", MyDsl.class);
        if(!myDsl.master.nodes.nodes.get(0).name.equals("mystage")) {
            throw new AssertionError("Failed with nested nodes");
        }

        // 2: this is how I need it
        Yaml yaml2 = new Yaml(new MyConstructor());
        MyDsl myDsl2 = yaml2.loadAs("master:\n  nodes:\n    - name: mystage", MyDsl.class);
        if(!myDsl2.master.nodes.nodes.get(0).name.equals("mystage")) {
            throw new AssertionError("Failed with leaving out nodes");
        }
    }
}