How do I query a set of objects with an array of values in mongoose?

问题

I have a schema like this

const rankSchema = new Schema(
  {
    rank: { type: Object, default: {} },
    lastUpdated: { type: Date, default: Date.now() },
  },
  { minimize: false }
);

And my database has an object 'rank' with many other objects inside of it like this.

rank: {
  Person1: { Stat1: 2, Stat2: 0, Stat3: 0, Stat4: 2, Stat5: 4 },
  Person2: { Stat1: 4, Stat2: 0, Stat3: 0, Stat4: 2, Stat5: 2 },
  Person3: { Stat1: 1, Stat2: 0, Stat3: 0, Stat4: 2, Stat5: 1 },
  Person4: { Stat1: 2, Stat2: 0, Stat3: 0, Stat4: 2, Stat5: 3 }
}

Now I have an array of strings that contains a few of these people

['Person1', 'Person2']

I want to be able to find all the person objects in that array and return their stats. So essentially the final output after using the array of strings would be

Person1: { Stat1: 2, Stat2: 0, Stat3: 0, Stat4: 2, Stat5: 4 },
Person2: { Stat1: 4, Stat2: 0, Stat3: 0, Stat4: 2, Stat5: 2 }

I tried using $in and various different queries but nothing seems to work and I am stumped.

Thanks

回答1:

You could use a combination of $objectToArray and $arrayToObject to filter your object by dynamic field names but if your parameters are known when you're building your query then it's easier to use regular .find() and apply projection:

db.collection.find({},{ "rank.Person1": 1,  "rank.Person2": 1})

let input = ['Person1', 'Person2'];
let entries = input.map(p => ([`rank.${p}`, 1]))
let projection = Object.fromEntries(entries);
console.log(projection);

Mongo Playground

来源：https://stackoverflow.com/questions/62772021/how-do-i-query-a-set-of-objects-with-an-array-of-values-in-mongoose

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