Should I use uppercase or camelcase in label enums?

Question

The title says it all.

In cypher, camelcase is used for labels. For instance :Car and :Bike. The API docs for Label uses uppercase when defining each label in the enum, so then Label.CAR.name() will always be CAR, not Car.

Using camelcase fits in more nicely with cypher queries, but this conflicts with the Java standard for naming enum members. This forces me to use labels like Label.BIKE_SEAT instead of Label.BikeSeat in my graph database. Which one should I use?

Even though using uppercase for enum members is the correct way to do it in Java, I'm still a bit curious about why the Neo4j people then decided to represent labels as an enums?

Answer 1

First approach to a solution

To comply with the Java convention, I can override Enum#toString() and use that instead of Enum#name() which cannot be overridden. Then each member will have a constructor with its real Neo4j label as represented in the graph database:

public enum Label implements org.neo4j.graphdb.Label {
  CAR("Car"),
  BIKE("Bike"),
  BUS("Bus");

  private String name;

  private Label(name) {
    this.name = name;
  }

  @Override
  public String toString() {
    return name;
  }
}      

This doesn't work well with methods such as GraphDatabaseService#findNodesByLabelAndProperty(Label, String, String) because it seems to be using Label#name() for matching instead of Label#toString() so it won't match nodes having camel case labels in the db.

My working solution

Since overriding Enum#toString() doesn't work and since Neo4j uses Label#name() for everything internally, I'll need to override it anyway. So I ended up defining a class implementing Label which is able to override Label#name():

public class Label implements org.neo4j.graphdb.Label {
  public static final Label CAR = new Label("Car");
  public static final Label BIKE = new Label("Bike");
  public static final Label BUS = new Label("Bus");

  private String name;

  private Label(String name) {
    this.name = name;
  }

  @Override
  public String name() {
    return name;
  }

  @Override
  public String toString() {
    return name;
  }
}

Externally, no changes are needed on the client side using the previous label enum.

Answer 2

ORACLE DOC : Because they are constants, the names of an enum type's fields are in uppercase letters.

check : http://docs.oracle.com/javase/tutorial/java/javaOO/enum.html