Question

I am using <ui:repeat> for displaying a list. Now I want to export whole list to the CSV file. Is there any way to do this in JSF 2.0?

Answer 1

Yes, there’s a way. Add a command button which says “export”.

<h:form>
    <h:commandButton value="export" action="#{bean.export}" />
</h:form>

Then, in the export() method, iterate over the List<Something> which you’re displaying there in the <ui:repeat> and print each row/column in valid CSV format. The CSV format rules are very simple, there are only 3:

• Fields are separated by a comma.
• If a comma occurs within a field, then the field has to be surrounded by double quotes.
• If a double quote occurs within a field, then the field has to be surrounded by double quotes and the double quote within the field has to be escaped by another double quote.

So it’ll look something like this:

public void export() throws IOException {
    FacesContext fc = FacesContext.getCurrentInstance();
    ExternalContext ec = fc.getExternalContext();
    String filename = "somename.csv";

    ec.responseReset();
    ec.setResponseContentType("text/csv");
    ec.setResponseHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");
    Writer writer = ec.getResponseOutputWriter();

    for (Something something : somethings) { // somethings is your List<Something>
        writer.append(toCsvField(something.getFoo()))
              .append(',')
              .append(toCsvField(something.getBar()))
              .append(',');
              .append(toCsvField(something.getBaz()))
              .append('\n');
    }       

    fc.responseComplete(); // Important! Otherwise JSF will perform navigation.
}

public static String toCsvField(Object value) {
    if (value == null) {
        return "";
    }

    String field = String.valueOf(value).replace("\"", "\"\"");

    if (field.indexOf(',') > -1 || field.indexOf('"') > -1) {
        field = '"' + field + '"';
    }

    return field;
}