How do I check for an empty field in a child entry?

Question

I have an Event entry which can has one child Location entry. The Location entry has two fields: Title and Floor. Sometimes floor is empty so I'm doing this in my template to see if there's a floor entered:

<h2>
  {event_location:title}
  {if event_location:floor}
    , {event_location:floor}
  {/if}
</h2>

...and it's not working. Title always shows up and Floor never does unless I take off the conditional, which I don't want to do because I don't want a comma followed by nothing when there's no floor. Any ideas?

Answer 1

What version are you using? We fixed this problem in 2.9.3, though you can apply the solution if you'd rather not update.

---

Open system/expressionengine/libraries/channel_entries_parser/Preparser.php and find the _find_modified_conditionals() method around line 374, and replace it with this:

public function _find_modified_conditionals()
{
    $prefix = $this->_prefix;
    $unfiltered_all_field_names = array();
    $all_field_names = array();

    if (strpos($this->_tagdata, LD.'if') === FALSE)
    {
        return array();
    }

    foreach($this->_channel->cfields as $site_id => $fields)
    {
        $unfiltered_all_field_names = array_unique(array_merge($unfiltered_all_field_names, $fields));
    }

    // Do a rough cut to slim down the number of fields
    // else the string can be too long for the preg_match_all
    foreach (array_keys($unfiltered_all_field_names) as $name)
    {
        if (strpos($this->_tagdata, $name) !== FALSE)
        {
            $all_field_names[] = $name;
        }
    }       

    $modified_field_options = $prefix.implode('|'.$prefix, $all_field_names);
    $modified_conditionals = array();

    if (preg_match_all("/".preg_quote(LD)."((if:(else))*if)\s+(($modified_field_options):(\w+))(.*?)".preg_quote(RD)."/s", $this->_tagdata, $matches))
    {
        foreach($matches[5] as $match_key => $field_name)
        {
            $modified_conditionals[$field_name][] = $matches[6][$match_key];
        }
    }

    return array_map('array_unique', $modified_conditionals);
}

Answer 2

I've found the right syntax to use from looking at this question: Conditionally display a field from a related entry if it's not empty (native relationships field). Basically, the field needs to be compared against an empty string as so:

<h2>
  {event_location:title}
  {if '{event_location:floor}' != ""}
    , {event_location:floor}
  {/if}
</h2>

Not remotely elegant, but this did the trick.