How to check that a user has already voted on a poll? - mongodb

Question

SITUATION:
Currently, I store an array of objects inside my User which contains all the votes he has cast.
Here is the model:
var schema = new Schema({
firstName: {type: String, required: true},
lastName: {type: String, required: true},
password: {type: String, required: true},
email: {type: String, required: true, unique: true},
polls: [{type: Schema.Types.ObjectId, ref: 'Poll'}]
votes: [{
poll: {type: Schema.Types.ObjectId, ref: 'Poll'},
choice: {type: number}
}]
});
When a user selects an option, this method is triggered inside my service:
voteOn(poll: Poll, userID: string, choice: number) {
UserModel.findById(userID, function (err, user) {
user.votes.push({poll, choice });
const body = JSON.stringify(user);
const headers = new Headers({'Content-Type': 'application/json'});
const token = localStorage.getItem('token')
? '?token=' + localStorage.getItem('token')
: '';
return this.http.patch('https://voting-app-10.herokuapp.com/user'+token, body, {headers: headers})
.map((response: Response) => response.json())
.catch((error: Response) => {
this.errorService.handleError(error);
return Observable.throw(error);
})
.subscribe();
});
}
This method saves the poll the user has voted and the choice he made inside the votes array of the user.
My problem is the following:
PROBLEM:
When the polls load, I would like to show the polls on which the user has already voted on as having the choice he made pre-selected as well as preventing him from voting more than once.
How can I achieve that ?
Here is the method inside my service which gets the polls:
getPolls() {
return this.http.get('https://voting-app-10.herokuapp.com/poll')
.map((response: Response) => {
const polls = response.json().obj;
let transformedPolls: Poll[] = [];
polls.reverse();
for (let poll of polls) {
transformedPolls.push(new Poll(
poll.title,
poll.choice1,
poll.choice2,
poll.counter1,
poll.counter2,
poll.user.firstName,
poll._id,
poll.user._id,
)
);
}
this.polls = transformedPolls;
return transformedPolls;
})
.catch((error: Response) => {
this.errorService.handleError(error);
return Observable.throw(error);
});
}
And here is the component.html for a poll:
<article class="panel panel-default">
<div class="panel-body">
{{ poll.title }}
<br>
<br>
<form #form="ngForm">
{{ poll.counter1 }} votes <input type="radio" id="{{ poll.choice1 }}" name="my_radio" value="{{ poll.choice1 }}" (click)="onChoice1(form)"> {{ poll.choice1 }}
<br>
{{ poll.counter2 }} votes <input type="radio" id="{{ poll.choice2 }}" name="my_radio" value="{{ poll.choice2 }}" (click)="onChoice2(form)"> {{ poll.choice2 }}
</form>
</div>
<footer class="panel-footer">
<div class="author">
{{ poll.username }}
</div>
<div class="config" *ngIf="belongsToUser()">
<a (click)="onEdit()">Edit</a>
<a (click)="onDelete()">Delete</a>
</div>
</footer>
</article>

Answer 1

There are a lot of ways you could do this.
Without changing your current data model what you need to do is compare the poll.id to the user.votes[pollIndex].id and if they match disable input on the poll. Coming from a ReactJS background I could advise how to do this but IDK with angular.
If I were to take over this project, I would probably make a new Mongo schema called Vote or UserPoll like:
{
user: {type: Schema.Types.ObjectId, ref: 'User'),
poll: {type: Schema.Types.ObjectId, ref: 'Poll'},
choice: {type: number}
}
Then if a user want to take a poll, create a new UserPoll object with the current user and poll. Then you can find all the UserPolls that the current User is in and then use an array filter based on if there is a choice or not.
Hopefully that makes sense.