Calculation of third field based on two other field in Mongoose

user_4056534 0
Viewed 2519

I have 2 fields on on Mongoose model: totalAttempts and totalRight. I am planning to calculate accuracy based on them. 

totalAttempts: {
    type: Number,
    default: 1
},
totalRight: { 
    type: Number,
    default: 1
}

This is what I have done [it doesn't work]

 accuracy:{
     type:Number,
     required:function() {return (this.totalRight/this.totalAttempts*100).toFixed(2)}
}

Also, if I don't put default value on Accuracy I get an error:

ERROR; While creating new question ..ValidationError: Path `accuracy` is require                      d.

events.js:163

What will be the right way to accomplish this ? I already have a working solution to get totalAttempts and totalRight every time user request that Model. But I want to save that calculation and store info on my database.

mongoose-schema mongoose node.js mongodb
3 Answers

You don't need to calculate it before you save the document. You just need to add a virtual field that gets the value of accuracy when you need it

yourSchema.virtual("accuracy").get(function () {
    return this.totalRight/this.totalAttempts*100).toFixed(2)
});

now when you query this document you will get accuracy but don't forget to use .toJSON({ virtuals: true }) on your document query

for more about virtuals in mongoose check mongoose virtuals. when using lean use this plugin mongoose-lean-virtuals.

user_104958890

try this :

 accuracy:{
     type: Number,
     required:true,
     default: function() {
     return (this.totalRight/this.totalAttempts*100).toFixed(2)
}}
user_198305090
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