Create unique array in MongoDB

Question

I have a field of zipcode in which we can enter multiple zipcodes. It is an array field and I want it should be unique.

Mongoose schema -

const RegionalZones = new Schema({
    name :      { type : String, required : true },
    country :   { type : String, required : true },
    zipCodes :  { type : Array,  required : true},
    isBlocked:  { type: Boolean, default : false },
    serviceTax: { type: Number,  default:10},
    cancelFee:  {type: Number,   default: 7.50},
    contractorCancelFee: {type: Number,   default: 7.50},
    createdAt : {type : Date,    default : Date.now},
    updatedAt : {type : Date,    default : Date.now}
});

RegionalZones.index({ country: 1, zipCodes: 1,name:1 }, { unique: true });

module.exports = mongoose.model('RegionalZones', RegionalZones);

I have a field of zipcode in which we can enter multiple zipcodes means it is an array field I want it should be unique like if I enter 303030 and [303030,123456] then it should not throw an error but it does if I make it unique — Mamta
– Mamta, Commented Feb 14, 2017 at 7:35
This will help me to ask a query on stackoverflow stackoverflow.com/help/how-to-ask — Prasad
– Prasad, Commented Feb 14, 2017 at 8:35

Israel Zinc · Accepted Answer · 2017-02-14 07:47:03Z

8

the keyword unique means that there will be only one document with this value in the whole collection. For example, if a document has a zip-code 1, no other document will be able to have it, which I assume is not your desired effect.

What you're looking for is the $addToSet command.

My suggestion is that you remove the unique modifier from this field and instead, when inserting data to this array, use the $addToSet command.

Here is a sample code that I used in past projects:

User.findByIdAndUpdate(id, { $addToSet : {accounts : accountId } } )

In my example, it will find an user by id and add one account on it. But if it already have an account, it won't duplicate the value.

Hope it was helpful.

answered Feb 14, 2017 at 7:47

Israel Zinc

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