JanusGraph: Define property keys

Vertexes and edges in janus graph has zero or more properties Property is a simple <key, value> pair.

 

for example, the property name='Krishna' has the key name and value 'Krishna'.

 

Property key name must be unique within a graph. As per the documentation, spaces and special characters should be avoided in property key name.

 

Can a property takes more than one value?

Yes, you can attach multiple values to a property key. Default cardinality is set to SINGLE.

 

Can I constrain a property to specific type?

Yes, you can constrain datatype. At the time of writing this post, JanusGraph support below datatypes.

 

Data type	Description
String	Specifies a character sequence
Character	Specifies single character
Boolean	Specifies true or false
Byte	Specifies byte value
Short	Specifies short value
Integer	Specifies integer value
Long	Specifies long value
Float	Specifies 4 byte floating point number
Double	Specifies 8 byte floating point number
Date	Specific instant in time (java.util.Date)
Geoshape	Specifies Geographic shape like point, circle or box
UUID	Specifies Universally unique identifier (java.util.UUID)

 

Property key cardinality

By specifying the Cardinality, we can set the cardinality of the values associated with given key for a particular element.

 

Below table summarizes the possible key cardinalities.

 

Cardinality	Description
SINGLE	At most one value is associated with the key
LIST	Multiple values and duplicate values may be associated with the given key.
SET	Multiple but distinct values may be associated with the given key.

 

Example

PropertyKeyMaker propertyKeyMaker = janusGraphManagement.makePropertyKey("hobbies");
propertyKeyMaker.cardinality(Cardinality.SET);
propertyKeyMaker.dataType(String.class);

PropertyKey propertyKey = propertyKeyMaker.make();

 

Find the below working application.

 

ModelPropertyKeys.java

 

package com.sample.app.schema;

import org.janusgraph.core.Cardinality;
import org.janusgraph.core.JanusGraph;
import org.janusgraph.core.JanusGraphFactory;
import org.janusgraph.core.PropertyKey;
import org.janusgraph.core.schema.JanusGraphManagement;
import org.janusgraph.core.schema.PropertyKeyMaker;

public class ModelPropertyKeys {
	public static void main(String args[]) {

		try (JanusGraph janusGraph = JanusGraphFactory.open("/Users/Shared/janus.properties")) {

			JanusGraphManagement janusGraphManagement = janusGraph.openManagement();

			PropertyKeyMaker propertyKeyMaker = janusGraphManagement.makePropertyKey("hobbies");
			propertyKeyMaker.cardinality(Cardinality.SET);
			propertyKeyMaker.dataType(String.class);

			PropertyKey propertyKey = propertyKeyMaker.make();

			String propertyKeys = janusGraphManagement.printPropertyKeys();

			System.out.println(propertyKeys);
		} finally {
			System.out.println("\nDone!!!");
		}

	}
}

Output

------------------------------------------------------------------------------------------------
Property Key Name              | Cardinality | Data Type                                          |
---------------------------------------------------------------------------------------------------
hobbies                        | SET         | class java.lang.String                             |
---------------------------------------------------------------------------------------------------


Done!!!

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