Display a onetomany relationship in dataTable

Question

i have two classes Email and Data. The relationship between them is OneToMany. In the data table of datas i want to display the list of emails it contains. How can i do that? These are parts of my entities:

  @Entity
@Table(name = "EMAILS")
public class Email implements Serializable { 
    @Id
    @Column(name = "id")
    private String id;
    @Column(name = "extraction_Date")
    @Temporal(TemporalType.TIMESTAMP)
    private Date date;
    @Size(max = 255)
    @Column(name = "email")
    private String email;
    @ManyToOne(cascade = CascadeType.PERSIST)
    private Data dataBase;

    public Email() {
        this.date = new Date();
        this.id = IdGenerator.IdGenerathorCall();

    }
    @Entity
@Table(name = "DATAS")
public class Data implements Serializable {

    @Id
    @Column(name = "id")
    private String id;
    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "creation")
    private Date date;
    @Column(name = "timeofextraction")
    private float grabduration;
    @Column(name = "keyword")
    private String keyword;
    @Column(name = "number")
    private int number;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "dataBase", fetch = FetchType.EAGER)
    private List<Email> emails;

    public Data() {
        super();
        this.date = new Date();
        this.id = IdGenerator.IdGenerathorCall();
    }

My page dataList.xhtml looks like:

 <p:dataTable value="#{dataMB.datas}" var="item" id="datas"  rowsPerPageTemplate="5,10,15,20,25,30" 
                                      paginator="true" rows="10" filteredValue="#{dataMB.filteredDatas}"
                                      selectionMode="single" rowKey="#{item.id}"
                                      selection="#{dataMB.selectedData}">
                        <p:ajax event="rowSelect" update=":form:dataView , :form:confirmDelete"/>
                        <p:column sortBy="#{item.date}" filterBy="#{item.date}">
                            <f:facet name="header">
                                <p:outputLabel value="Creation"/>
                            </f:facet>
                            <p:outputLabel value="#{item.date}">
                                <f:convertDateTime pattern="MM/dd/yyyy HH:mm:ss" />
                            </p:outputLabel>
                        </p:column>
                        <p:column sortBy="#{item.grabduration}" filterBy="#{item.grabduration}">
                            <f:facet name="header">
                                <h:outputText value="Time of execution"/>
                            </f:facet>
                            <h:outputText value="#{item.grabduration}"/>
                        </p:column>
                        <p:column sortBy="#{item.keyword}" filterBy="#{item.keyword}">
                            <f:facet name="header">
                                <h:outputText value="Keyword"/>
                            </f:facet>
                            <h:outputText value="#{item.keyword}"/>
                        </p:column>
                        <p:column sortBy="#{item.number}" filterBy="#{item.number}">
                            <f:facet name="header">
                                <h:outputText value="Number"/>
                            </f:facet>
                            <h:outputText value="#{item.number}"/>
                        </p:column>      
                          <p:column sortBy="#{item.emails}" filterBy="#{item.emails}">
                            <f:facet name="header">
                                <h:outputText value="Emails List"/>
                            </f:facet>
                            <h:outputText value="#{item.emails}"/>
                        </p:column>  
                    </p:dataTable> 

When i display the dataTable the column containing the emails list is empty nothing is shown.

Answer 1

You are trying to render a list in a single value component.

Change your emails column to this:

<p:column headerText="Emails List">
    <p:dataList  value="#{item.emails}" var="email" itemType="none">
        #{email.email}
    </p:dataList>
</p:column>

In addition to this you will need to make an auxiliary method to sort and filter by emails.