static ValueExpression createValueExpressionFromField(FacesContext context, String var, String field) {
        if (LangUtils.isBlank(var) || LangUtils.isBlank(field)) {
            throw new FacesException("Table 'var' and Column 'field' attributes must be non null.");
        }

        return context.getApplication().getExpressionFactory()
                .createValueExpression(context.getELContext(), "#{" + var + "." + field + "}", Object.class);
    }
Used to build a valid {@link ValueExpression} using {@link UIData#getVar()} and {@link UIColumn#getField()}
Mostly used if sortBy and/or filterBy are not defined.

var="car" and field="name" -&gt; #{car.name}

@param context the {@link FacesContext}
@param var the "var" attribute of the parent table
@param field the "field" attribute of the column
@return the {@link ValueExpression}
primefaces/src/main/java/org/primefaces/component/api/UIColumn.java