未知的顶级运算符：$eq

Question

我的数据库示例：

{
  name: 'The Perks of Being a Wallflower'
  genres: ['Drama', 'Romance']
  rating: 8
}, 
{
  name: 'The Edge of Seventeen'
  genres: ['Drama', 'Comedy']
  rating: 7.3
},
{
  name: 'Little Women',
  genres: ['Drama', 'Romance']
  rating: 7.8
}

如果流派数组的第一个元素是 Comedy 或 Romance.
，我想投影它我试过了：

db.shows.find(
  {},
  { genres: { $elemMatch: { $or: [{ $eq: 'Drama' }, {$eq: 'Comedy'}] } } }
);

但它给我这个错误“未知的顶级运算符：$eq”。

Answer 1

使用$in

The $in operator selects the documents where the value of a field equals any value in the specified array. To specify an $in expression, use the following prototype:

演示 - https://mongoplayground.net/p/MAuWUeP9GIE

db.collection.find({
  genres: {
    $elemMatch: {
      "$in": [ "Drama", "Comedy" ]
    }
  }
})

演示 - https://mongoplayground.net/p/JJJkoHuz_DZ

db.collection.find({},
{
  genres: {
    $elemMatch: {
      "$in": [ "Drama", "Comedy" ]
    }
  }
})

未知的顶级运算符：$eq

unknown top level operator: $eq

database

mongodb

mongodb-shell

mongodb-query