[PURR-82] added __isset() to Relational class

[JackS9]

This is an alternate solution to PR 1661

• JIRA issue: https://sdx-sdsc.atlassian.net/browse/PURR-82
• Support ticket: https://purr.purdue.edu/support/ticket/2439?show=324&search=&limit=20&start=0
• Summary of issue: In the publication curation workflow the title of the citation does not appear. In fact the citation is essentially blank.
• Summary of fix: The test for the presence of a citation key (such as title) was incorrectly returning false even though it was set. Added a magic __isset() to core/libraries/Hubzero/Database/Relational.php that checks whether the attribute is set.
• Summary of testing: The issue was replicated on my dev machine and now works with this fix.
• Hotfix needed? Possibly on PURR.

[zooley]

Just a note that this functionality already exists on the Relational class in the form of the hasAttribute() method. Adding an __isset magic method isn't a bad idea, though, but should probably just return the other method (or vice-versa).

    /**
     * Check if attributes (i.e. field) on the model is set
     *
     * @param  string  $name   The key to check if set
     * @return  boolean 
     */
    public function __isset($name)
    {
        return $this->hasAttribute($name);
    }

[JackS9]

I changed to what Shawn suggested; however, I noticed that __get() could also use hasAttribute()

    // Next check for an attribute on the model
    if (isset($this->attributes[$name]))
    {
        return $this->attributes[$name];
    }