diff --git a/src/main/java/org/wikitolearn/wikirating/model/User.java b/src/main/java/org/wikitolearn/wikirating/model/User.java
index f2bbdc5..157c2de 100644
--- a/src/main/java/org/wikitolearn/wikirating/model/User.java
+++ b/src/main/java/org/wikitolearn/wikirating/model/User.java
@@ -1,173 +1,182 @@
 /**
  * 
  */
 package org.wikitolearn.wikirating.model;
 
 import org.neo4j.ogm.annotation.GraphId;
 import org.neo4j.ogm.annotation.Index;
 import org.neo4j.ogm.annotation.NodeEntity;
 
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import org.neo4j.ogm.annotation.Relationship;
 
+import java.util.HashSet;
 import java.util.Set;
 
 /**
  * @author aletundo, valsdav
  *
  */
 @NodeEntity( label = "User")
 @JsonIgnoreProperties(ignoreUnknown = true)
 public class User {
     @GraphId private Long graphId;
     @JsonProperty("name")
 	private String username;
     @Index(unique=true,primary = true)
 	private int userid;
 	private double votesReliability;
 	private double contributesReliability;
 	private double totalReliability;
 	@Relationship( type="AUTHOR", direction = Relationship.OUTGOING)
 	private Set<Author> authors;
 	@Relationship( type="VOTE", direction = Relationship.OUTGOING)
 	private Set<Vote> votes;
 	
 	/**
 	 * 
 	 */
-	public User() {}
+	public User() {
+	    this.authors = new HashSet<>();
+	    this.votes = new HashSet<>();
+    }
 	
 	/**
 	 * @param username
 	 * @param userid
 	 * @param votesReliability
 	 * @param contributesReliability
 	 * @param totalReliability
 	 */
 	public User(String username, int userid, double votesReliability, double contributesReliability,
 			double totalReliability) {
 		this.username = username;
 		this.userid = userid;
 		this.votesReliability = votesReliability;
 		this.contributesReliability = contributesReliability;
 		this.totalReliability = totalReliability;
+        this.authors = new HashSet<>();
+        this.votes = new HashSet<>();
 	}
 
 	/**
 	 * @return the username
 	 */
 	public String getUsername() {
 		return username;
 	}
 
 	/**
 	 * @param username the username to set
 	 */
 	public void setUsername(String username) {
 		this.username = username;
 	}
 
 	/**
 	 * @return the userid
 	 */
 	public int getUserid() {
 		return userid;
 	}
 
 	/**
 	 * @param userid the userid to set
 	 */
 	public void setUserId(int userid) {
 		this.userid = userid;
 	}
 
 	/**
 	 * @return the votesReliability
 	 */
 	public double getVotesReliability() {
 		return votesReliability;
 	}
 
 	/**
 	 * @param votesReliability the votesReliability to set
 	 */
 	public void setVotesReliability(double votesReliability) {
 		this.votesReliability = votesReliability;
 	}
 
 	/**
 	 * @return the contributesReliability
 	 */
 	public double getContributesReliability() {
 		return contributesReliability;
 	}
 
 	/**
 	 * @param contributesReliability the contributesReliability to set
 	 */
 	public void setContributesReliability(double contributesReliability) {
 		this.contributesReliability = contributesReliability;
 	}
 
 	/**
 	 * @return the totalReliability
 	 */
 	public double getTotalReliability() {
 		return totalReliability;
 	}
 
 	/**
 	 * @param totalReliability the totalReliability to set
 	 */
 	public void setTotalReliability(double totalReliability) {
 		this.totalReliability = totalReliability;
 	}
 
 	/**
 	 *
 	 * @return
 	 */
 	public Set<Author> getAuthors() {
 		return authors;
 	}
 
 	/**
 	 *
 	 * @param authors
 	 */
 	public void setAuthors(Set<Author> authors) {
 		this.authors = authors;
 	}
 
 	public void addAuthor(Author author){
 	    this.authors.add(author);
     }
 
 	/**
 	 * 
 	 * @return the votes of the user
 	 */
 	public Set<Vote> getVotes() {
 		return votes;
 	}
 	
 	/**
 	 * 
 	 * @param votes the votes to set
 	 */
 	public void setVotes(Set<Vote> votes) {
 		this.votes = votes;
 	}
 
+	public void addVote(Vote vote){
+	    this.votes.add(vote);
+    }
 
 	/* (non-Javadoc)
              * @see java.lang.Object#toString()
              */
 	@Override
 	public String toString() {
 		return "User [username=" + username + ", userid=" + userid + ", votesReliability=" + votesReliability
 				+ ", contributesReliability=" + contributesReliability + ", totalReliability=" + totalReliability + "]";
 	}
 	
 }