JSF: Redirection

Question

I'm using JSF 2.2 with primefaces. I have a primefaces datatables, i have program a method who's call when i click on a row, and this redirect me on a page with the data of the row.

The problem is: when i click on the row, i'm redirect to the good page, but if it's the first time i'm redirect, the program just ignore my @PostConstruct. But it's work for next time...

My datatable:

                <p:contextMenu for="books">
                    <p:menuitem value="Détails" icon="ui-icon-search" actionListener="#{indexCtrl.showDetails()}"/>
                </p:contextMenu>
                <h2>Liste des bouquins de l'application <span style="font-weight:bold; color:#4592BE;">BookLib</span></h2>
                <p:dataTable id="books" var="book" value="#{indexCtrl.books}" rowKey="#{book.ISBN}" selection="#{indexCtrl.selectedBook}" selectionMode="single">
                    <p:ajax event="rowSelect" listener="#{indexCtrl.showDetails}"/>
                    <p:column headerText="Title">
                        <h:outputText value="#{book.title}" />
                    </p:column>

                    <p:column headerText="Publish Date">
                        <h:outputText value="#{book.publish_date}" />
                    </p:column>

                    <p:column headerText="Pagination">
                        <h:outputText value="#{book.pagination}" />
                    </p:column>
                    <p:column headerText="image">
                        <p:graphicImage url="#{book.cover.small}" />
                    </p:column>
                </p:dataTable>

My ShowDetail method:

    public void showDetails() throws IOException{
    Faces.setFlashAttribute("bookToView", selectedBook);
    String url = "details.xhtml";
    FacesContext.getCurrentInstance().getExternalContext().redirect(url); 
}

My PostConstruct for detailsCtrl:

@PostConstruct
public void init(){
    setBookToView((Book)Faces.getFlashAttribute("bookToView"));
    this.constructAuthorsString();
}

ALl my beans are in ViewScoped.