How to Include or Exclude Fields in MongoDB Query Results using mongo-go-driver?

Including or Excluding Fields in Query Results with mongo-go-driver

The mongo-go-driver offers a mechanism to filter fields from query results, allowing you to include or exclude specific fields based on your requirements. However, when attempting to use the findopt.Projection option, you may encounter issues if the field names are not exported correctly.

To address this, ensure that your field names begin with an uppercase letter, indicating exported fields. Additionally, you can use struct tags to map the MongoDB field names to your Go struct fields, as shown in the following example:

type fields struct {
    ID int16 `bson:"_id"`
}

With the field names properly exported, you can perform a query using a projection as follows:

var opts []*find.FindOptions
projection := fields{
    ID: 0,
}
opts = append(opts, find.Projection(projection))
s := bson.NewDocument()
filter := bson.NewDocument(bson.EC.ObjectID("_id", starterId))
staCon.Collection.FindOne(nil, filter, opts...).Decode(s)

Alternatively, you can use a bson.M map to specify the projection:

options := find.FindOptions{}
options.Projection = bson.M{"_id": 0}
result := staCon.Collection.FindOne(nil, filter, &options).Decode(s)

By using proper field exports and a projection, you can effectively filter fields from your MongoDB query results, tailoring the responses to your specific needs.

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