MongoDB - Invalid Operator - Agregation
<p>So I have the following aggregation and I receive the error invalid operator $$event.info.</p>

<pre><code>db.days.aggregate([
    { 
        $match : { 'day' : 'March_1'}
    },
    {
        $project: 
        {
            _id:0,
            day: 1,
            events:
            {
               $filter:
               {
                    input: '$events',
                    as: 'event',
                    cond: 
                    {
                        $and: 
                        [
                            {
                                $eq: ['$$event.year', '2002']
                            },
                            {
                                '$$event.info' : {$regex: '.*peseta.*'}
                            }
                        ]
                    }
                }
            }  
        }
    }
])
</code></pre>

<p>Event is an array with objects of type </p>

<pre><code>{
    year : "x"
    info : "y"
}
</code></pre>

<p>Could you please help me some an explanation? </p>

<p>Thanks in advance!</p>