MongoDB: Conditional select from one collection based on another collection

Question

I\'m fairly new to MongoDB and need help doing a select, or perhaps some sort of left join, on one collection based on another collection\'s data.

I have two collections

Answer 1

MongoDB supports joins with $lookup , In your case you can use query like:-

    db.animals.aggregate([
    {
      $lookup:
        {
          from: "meals",
          localField: "lastMeal",
          foreignField: "id",
          as: "last_meal"
        }
   },
  {
   $match: { 
          "created" : {
                $gt: "date" //your date format
          }
       } 
 }
])

thanks !