How to handle error in Primefaces lazy load?

Question

I have problem to let user know about exceptions occurred in PrimeFaces LazyDataModel#load method.

I am loading there data from database and when an exception is raised, I have no idea how to inform the user about it.

I tried to add FacesMessage to FacesContext, but message is not shown on the Growl component, even if Growl is set to autoUpdate="true".

Using PrimeFaces 3.3.

Answer 1

It doesn't work because load() method is invoked during Render Response phase (you can check this by printing FacesContext.getCurrentInstance().getCurrentPhaseId()), when all messages have already been processed.

The only workaround that worked for me is to load the data within the "page" event listener of the DataTable.

html:

<p:dataTable value="#{controller.model}" binding="#{controller.table}">
     <p:ajax event="page" listener="#{controller.onPagination}" />
</p:dataTable>

Controller:

private List<DTO> listDTO;
private int rowCount;
private DataTable table;

private LazyDataModel<DTO> model = new LazyDataModel<DTO>() {
        @Override
        public List<DTO> load(int first, int pageSize, String sortField,
                SortOrder sortOrder, Map<String, String> filters) {
            setRowCount(rowCount);
            return listDTO;
        }
    };

public void onPagination(PageEvent event) {
    FacesContext ctx = FacesContext.getCurrentInstance();
    Map<String, String> params = ctx.getExternalContext()
            .getRequestParameterMap();

    // You cannot use DataTable.getRows() and DataTable.getFirst() here,
    // it seems that these fields are set during Render Response phase
    // and not during Update Model phase as one can expect.

    String clientId = table.getClientId();
    int first = Integer.parseInt(params.get(clientId + "_first"));
    int pageSize = Integer.parseInt(params.get(clientId + "_rows"));

    try {
        listDTO = DAO.query(first, pageSize);
        rowCount = DAO.getRowCount();
    } catch (SQLException e) {
        ctx.addMessage(null,
                new FacesMessage(FacesMessage.SEVERITY_ERROR,
                    "SQL error",
                    "SQL error"));
    }
}

Hope this helps.