CODEWITHSUNDEEP
javascriptjsonnode.jstypescript
Shikha thakur
Shikha thakur

Reputation: 1289

Error:Uncaught TypeError: Cannot read property 'groupBy' of undefined

I am facing an issue when i am trying to create a JSON structure like below:

enter image description here

so for this i am doing like below:

    class Aggregate{
    average: Number;
    count: String;
    max: Number;
    min: Number;
    total: Number;
    constructor(average,count,max,min,total) {
        this.average= average;
        this.count=count;
        this.max=max;
        this.min= min;
        this.total=total;
    }
}

var average = new Aggregate(43.833333333333336, 6, 90, 10, 263);
var aggregate = new Aggregate(0, undefined, 0, 0, 0);
var startDate=new Date("Tue Jul 05 2016 05:30:00 GMT+0530 (India Standard Time)");
var endDate=new Date("Tue Jul 05 2016 05:30:00 GMT+0530 (India Standard Time)");
interface date{
    aggregate: Aggregate;
    endDate: Date;
    groupBy: String;
    metricType: String;
    quarters: Array<DateMetric>;
    startDate: Date;
    type: String;
    quarter?: Number;
}
class DateMetric{
    aggregate: Aggregate;
    endDate: Date;
    groupBy: String;
    metricType: String;
    quarters: Array<DateMetric>;
    startDate: Date;
    type: String;
    quarter?: Number;

    constructor();
    constructor(obj: date);
    constructor(obj?: any) {
        this.aggregate= aggregate;
        this.endDate=endDate;
        this.groupBy=obj.groupBy;
        this.metricType= obj.metricType;
        this.quarters = obj.quarters;
        this.startDate = startDate;
        this.type = obj.type;
        this.quarter =obj.quarter;

    }    
}
var b = new DateMetric();
b.aggregate = aggregate;
b.quarter=4
b.startDate = startDate;


var a = new DateMetric({ aggregate: average, endDate: endDate, groupBy: "datetime", metricType: "distance_metric", quarters: [b], startDate: startDate, type: "person" })

but here i am getting an error saying:Cannot read property 'groupBy' of undefined

I have no idea why i am getting the error as obj in constructor should contain the object passed when creating an object a

Any help would be appreciated.

Upvotes: 0

Views: 1493

Answers (1)

Vlad Jerca
Vlad Jerca

Reputation: 2224

Define your constructor like this to get rid of the error.

constructor(obj: any | Date = {}) { }

this way if you create an instance without any data passed in the constructor, basically you are accessing.

{}.groupBy; // ({} aka 'obj' is now defined)

With your existing code you can also just go ahead and put an if, like so:

constructor(obj: any | Date) { 
    if(!!obj) {
        // do stuff
    }
}

But for your example above, the first solution is best in my opinion :)

Upvotes: 1

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