I can't delete a row from datatable primefaces - jsf-2

Question

I know this ask is repeated, but none response help me to solve this problem.
I'm trying to delete a row from a primefaces datatable with a commandButton and a confirmDialog, this doesn't work because the backBean isn't getting the values. When I'm trying to delete this show me a null pointer exception. well see my code if you can help me.
This is my XHTML:
<h:form id="principalForm">
<p:menubar>
<p:menuitem value="Nuevo" icon="ui-icon-plusthick" oncomplete="PF('wdlgIngresar').show();"/>
</p:menubar>
<p:dataTable id="dtpacientes" value="#{beanPersona.listPersona}" var="per"
paginator="true" rows="15" rowsPerPageTemplate="15,20,30" paginatorPosition="bottom"
paginatorTemplate="{RowsPerPageDropdown} {FirstPageLink} {PreviousPageLink} {CurrentPageReport} {NextPageLink} {LastPageLink}"
selectionMode="single" selection="#{beanPersona.currPersona}" rowKey="#{per.id}">
<p:ajax event="rowSelect" listener="#{beanPersona.onRowSelect}" update=":dlgVer" oncomplete="PF('wdlgVer').show()" />
<p:column headerText="Id" sortBy="#{per.id}" filterBy="#{per.id}">
<h:outputText value="#{per.id}" />
</p:column>
<p:column headerText="Nombre" sortBy="#{per.nombres} #{per.apellidos}" filterBy="#{per.nombres} #{per.apellidos}">
<h:outputText value="#{per.nombres} #{per.apellidos}" />
</p:column>
<p:column headerText="Correo" sortBy="#{per.correo}" filterBy="#{per.correo}">
<h:outputText value="#{per.correo}" />
</p:column>
<p:column headerText="Edad" >
<h:outputText value="#{beanPersona.getEdad(per.nacimiento)}" />
</p:column>
<p:column headerText="Sexo" >
<h:outputText value="#{beanPersona.getSexo(per.sexo)}" />
</p:column>
<p:column id="actions" headerText="Acciones">
<p:commandButton title="Borrar" icon="ui-icon-trash" update=":principalForm:deleteConfirmDialog"
oncomplete="PF('deleteConfirmation').show();" actionListener="#{beanPersona.nullMethod}">
<f:setPropertyActionListener value="#{per}" target="#{beanPersona.currPersona}" />
</p:commandButton>
</p:column>
</p:dataTable>
<!-- HERE beanPersona.currPersona.id HAVE THE CURRENT VALUE CORRECTLY-->
<p:confirmDialog id="deleteConfirmDialog" header="Atencion!" severity="alert" widgetVar="deleteConfirmation"
message="Desea eliminar paciente Nº #{beanPersona.currPersona.id} ?" >
<p:commandButton id="confirm" value="Sí" oncomplete="PF('deleteConfirmation').hide();"
update=":principalForm:dtpacientes" action="#{beanPersona.eliminar(beanPersona.currPersona)}" />
<p:commandButton id="decline" value="No" oncomplete="PF('deleteConfirmation').hide();"/>
</p:confirmDialog>
</h:form>
This is my Bean:
#ManagedBean
#ViewScoped
public class BeanPersona implements Serializable {
private Persona persona = new Persona();
private Persona currPersona = new Persona();
public BeanPersona() {
persona = new Persona();
currPersona = new Persona();
}
public Persona getCurrPersona() {
return currPersona;
}
public void setCurrPersona(Persona currPersona) {
this.currPersona = currPersona;
}
public Persona getPersona() {
return persona;
}
public void setPersona(Persona persona) {
this.persona = persona;
}
public void eliminar(Persona currPersona) {
if(currPersona != null) {
new Dml().delete(currPersona, currPersona.getId());
listar();
System.out.println("succefull delete !!!!");
} else if(this.currPersona != null){
new Dml().delete(this.currPersona, this.currPersona.getId());
this.currPersona = new Persona();
listar();
System.out.println("succefull delete this.currPersona!!!!");
} else {
System.out.println("currPersona is null !!!!");
}
}
public String nullMethod () {return null;}
}
currPersona still null when I throw the method

Answer 1

The attribute onclick is for client side behaviour like executing some JS or showing up a dialog etc. You are not defining an actionListener for your commandButton at all.
Try to remove the onclick completely and use a proper actionListener instead:
<p:column id="actions" headerText="Acciones">
<p:commandButton title="Borrar" icon="ui-icon-trash"
update=":principalForm:deleteConfirmDialog"
oncomplete="PF('deleteConfirmation').show();"
actionListener="#{beanPersona.someActionListener}">
<f:setPropertyActionListener value="#{per}"
target="#{beanPersona.currPersona}" />
</p:commandButton>
</p:column>

Answer 2

I solved it, I just put process tag into "confirm" commandButton with value at "#this"
<p:column id="actions" headerText="Acciones">
<p:commandButton title="Borrar" icon="ui-icon-trash" update=":principalForm:deleteConfirmDialog"
oncomplete="PF('deleteConfirmation').show();" actionListener="#{beanPersona.setCurrPersona(per)}">
<f:setPropertyActionListener value="#{per}" target="#{beanPersona.currPersona}" />
</p:commandButton>
</p:column>
</p:dataTable>
<!-- HERE beanPersona.currPersona.id HAVE THE CURRENT VALUE CORRECTLY-->
<p:confirmDialog id="deleteConfirmDialog" header="Atencion!" severity="alert" widgetVar="deleteConfirmation"
message="Desea eliminar a paciente Nº #{beanPersona.currPersona.id} ?" closeOnEscape="true" >
<p:commandButton id="confirm" value="Sí" oncomplete="PF('deleteConfirmation').hide();"
update=":principalForm:dtpacientes" action="#{beanPersona.eliminar}" process="#this"/>
<p:commandButton id="decline" value="No" oncomplete="PF('deleteConfirmation').hide();"/>
</p:confirmDialog>