Saving unique array elements MongoDB

Question

I am trying to save a unique array of String elements using MongoDB but for some reason it allows me to save duplicates.

I am using mongoose. My code:

 schema = mongoose.Schema({
    "searchingId": { "type":  String,
        "unique": true,
        "index": true },
    "sharedTo" : {
        type: [String],
        unique: true,
        "trim":true
    }
}, {collection: 'myCollection'});

Basically the point is to keep a list of email addresses where the user had sent emails and to prevent the user from spamming them. But this schema will allow me to push any string to a sharedTo array and to .save() it no matter whether the duplicates exist. How to prevent this from happening?

EDIT: Lahar's answer does help with my question but not entierly. I would like to prevent user from adding emails if there is at least one duplicate. So basically $addToSet will help with uniqueness but not with my question.

Can you give examples of the kind of duplicate records you're trying to prevent, which it is allowing? — Vince Bowdren
– Vince Bowdren, Commented May 15, 2016 at 21:57

Lahar Shah · Accepted Answer · 2016-05-15 23:42:37Z

1

You can use $addToSet instead of $push to add email in "sharedTo" array. That won't add duplicate element(email in your case).

By providing unique:true to whole array field won't check uniqueness of array element.

Please check $addToSet documentation.

answered May 15, 2016 at 23:42

Lahar Shah

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4 Comments

Rouz Over a year ago

This is almost the answer I need. The problem is that I want to throw an error if there is a duplicate and to return 409 conflict. Is that even possible?

Lahar Shah Over a year ago

So when you run that update it returns writeResult object with count nMatched, nUpserted, nModified. nModified will tell you how many documents are modified.

Rouz Over a year ago

Yes but it saves the object to the database, so technically i would have to rollback to previous version if the modified is less than length of input? That sounds like dirty and wrong solution, doesn't it?

Lahar Shah Over a year ago

Can you provide the code snippet where you need to validate ? That will give better idea where and how you actually want.

Osama Salama · Accepted Answer · 2016-05-15 23:15:40Z

0

you can implement your own static function that will run from the schema class to do this for every email entered

UserSchema.statics.findUseremail = function(useremail, suffix,
callback) {

var _this = this;
var possibleuseremail = useremail + (suffix || '');
_this.findOne({
    useremail: possibleuseremail
    }, function(err, userem) {
    if (!err) {
        if (!userem) {
            callback(findUseremail);
        } else {
        return _this.findUseremail(useremail, (suffix || 0) +
        1, callback);
        }
    } else {
    callback(null);
    }
});
};

answered May 15, 2016 at 23:15

Osama Salama

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Rouz · Accepted Answer · 2016-05-17 08:33:04Z

0

So looks like I had found the solution myself but thanks to the Lahar Shah answer for pointing me in the right direction. Instead of using

Model.update(conditions, doc, [options], [callback])

I did

fetching the object
Added each of emails to my sharedTo attribute while checking for duplicates.
saving the object if no duplicates

Code:

var  length = emails.length;
for( var i = 0; i < length; i++ ) {
    var saved = doc.sharedTo.addToSet(emails[i]).length;
    if (saved != 1) {
        //status 409 - You have already sent email to user emails[i]
        return;
    }
}

doc[0].save(function(fail, success) {
    if(fail) {
        //error
    } else {
        //success return 200
    }
});

answered May 17, 2016 at 8:33

Rouz

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