Changing h:datatable cell color or style dynamically in JSF

Question

I have a datatable where I want to change the color of a cell based on some analysis that is run on the contents. The table is linked to an array of Comment objects, which I

Answer 1

In the standard JSF <h:dataTable> component, the rowClasses attribute is unfortunately not evaluated on a per-row basis. It's evaluated on a per-table basis. Component libraries like Tomahawk and PrimeFaces however support the kind of attribute which you're looking for on their <t:dataTable> and <p:dataTable>.

With the standard JSF <h:dataTable> component you need to supply a comma-separated string of all row classes. This can look something like this:

public String getRowClasses() {
    StringBuilder rowClasses = new StringBuilder();

    for (Comment comment : comments) {
        if (rowClasses.length() > 0) rowClasses.append(",");
        rowClasses.append(comment.getCssClass());
    }

    return rowClasses.toString();
}

which is then to be referenced as

<h:dataTable ... rowClasses="#{post.rowClasses}">

See also:

• <h:dataTable> tag documentation - lists all attributes and the accepted values