Searching for an array of objects within a MongoDB collection using queries

I have a collection where I store information in an array of objects named Degrees.

Each object in this array has keys like {Uni:'',Level:'',Degree:''}. I am trying to create a query that will help me find documents with a degree where the level = 'BS', regardless of the other fields in the object.

My current attempt looks like this:

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

However, this approach hasn't been successful. Do you have any suggestions for improvement?

javascriptarraysjsonmongodb

Answer №1

Directly access the fields of documents within the nested array through querying.

If your document structures resemble this:

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

You can retrieve all documents containing at least one 'BS' level degree by using this query:

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

Answer №2

When using the $elemMatch operator, it will find documents that have an array field containing at least one element that meets all of the specified criteria.

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

You can try this query to see if it works for you:

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

Make sure to substitute 'collection' with your model name. :)

For more information on how to use $elemMatch, visit the documentation here: mongoDb $elemMatch

Answer №3

After reviewing your query and assuming that your data set is named degrees, the solution appears to be quite straightforward:

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

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

If you're only interested in retrieving the first result, the following code can be used:

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

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

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