javascript - MongoDB query array of objects in collection - Stack Overflow

admin管理员组

文章数量:1347233

I have a collection, and inside this collection I have an array of objects called Degrees.

This array contains objects with keys {Uni:'',Level:'',Degree:''}, I want to be able to add to a parameter object the ability to find any document with a degree where level = 'BS', for example, regardless of what the other fields in the object contain.

I have tried so far:

{
  $elemMatch: {
    $eq: {
      Uni: {
        $exists: true,
        
      },
      Level: "BS",
      Degree: {
        $exists: true
      }
    }
  }
}

But it has not worked, any suggestions?

I have a collection, and inside this collection I have an array of objects called Degrees.

This array contains objects with keys {Uni:'',Level:'',Degree:''}, I want to be able to add to a parameter object the ability to find any document with a degree where level = 'BS', for example, regardless of what the other fields in the object contain.

I have tried so far:

{
  $elemMatch: {
    $eq: {
      Uni: {
        $exists: true,
        
      },
      Level: "BS",
      Degree: {
        $exists: true
      }
    }
  }
}

But it has not worked, any suggestions?

• javascript
• arrays
• json
• mongodb

Share Improve this question Follow edited Nov 20, 2020 at 14:55 J.F. 15.2k1010 gold badges3838 silver badges7272 bronze badges asked Dec 1, 2017 at 22:03 user7437896user7437896 6811 gold badge55 silver badges1111 bronze badges

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 4

You can query the fields of the documents in the embedded array directly.

If your documents look something like

{
 _id:ObjectId("..."),
 Name: "",
 degrees: [
           {Uni:"",
            Level:"BS",
            Degree:""}
          ]
 }

You could return all documents that contain at least one 'BS' level degree with

db.collection.find({"degrees.Level":"BS"})

The $elemMatch operator matches documents that contain an array field with at least one element that matches all the specified query criteria.

{ <field>: { $elemMatch: { <query1>, <query2>, ... } } }

I guess this should work for you :

db.collection.find({Degrees: {$elemMatch: {level:'BS'}}})

Don't forget to replace collection with ur model name. :)

Do checkout $elemMatch documetation here : mongoDb $elemMatch

If I'm understanding you correctly, and assuming your collection is called degrees, it should be as simple as:

// From the mongo shell:
db.degrees.find({ Level: 'BS' });

// From javascript (assuming node's native driver):
db.collection('degrees').find({ Level: 'BS' });

If you're interested in only the first result then you can use the following:

// From the mongo shell:
db.degrees.findOne({ Level: 'BS' });

// From javascript:
db.collection('degrees').findOne({ Level: 'BS' });

本文标签： javascriptMongoDB query array of objects in collectionStack Overflow