Creating a an Object of an Object Angular 4

Question

I have defined an interface :

export interface Student {
  name : String;
  section:String;
  phoneNumber:String;
}

i want to create an Object of an Object of type Student with studentId as key . i.e

studentDetails[studentId] should be of type Student;

studentDetails[studentId] : Student = [];

How can i implement this using inteface ?

Thanks in advance

i guess he is looking for a map operator on his object like {id: {name:..}} — Rahul Singh
– Rahul Singh, Commented Sep 1, 2017 at 6:05
oh ok, so that would be Map<number/string,Student> depending if the studentId is a string or number — Jota.Toledo
– Jota.Toledo, Commented Sep 1, 2017 at 6:08

Arg0n · Accepted Answer · 2017-09-01 09:51:34Z

21

You can define another interface for StudentDetails like this:

export interface Student {
  name: string;
  section: string;
  phoneNumber: string;
}

export interface StudentDetails {
  [key: number]: Student; //Or string instead of number
}

And use it like this:

//Valid
let studentDetails: StudentDetails = {
  1: {
    name: 'Test Person1',
    section: 'Section 1',
    phoneNumber: '12345678'
  }
};

//Valid
studentDetails[2] = {
  name: 'Test Person 2',
  section: 'Section 2',
  phoneNumber: '87654321'
};

//Invalid (properties in UpperCase)
studentDetails[3] = {
  Name: 'Test Person 3',
  Section: 'Section 3',
  PhoneNumber: '52376724'
};

//Valid
let student: Student = studentDetails[2];

UPDATE

From your comment to my answer, I assume you want something like this instead:

export interface Student {
  id: number; // Added
  name: string;
  section: string;
  phoneNumber: string;
}

export interface StudentMap {
  [key: number]: Student;
}

let studentMap: StudentMap = {};
let studentDetails: Student[] = [
  {
    id: 56,
    name: 'Test Person1',
    section: 'Section 1',
    phoneNumber: '12345678'
  },
  {
    id: 175,
    name: 'Test Person3',
    section: 'Section 3',
    phoneNumber: '521398763'
  }
];

studentDetails.forEach((s: Student) => {
  studentMap[s.id] = s;
});

for (let i = 0; i < studentDetails.length; i++) {
  console.log(studentMap[studentDetails[i].id].name); // Test Person1, Test Person 3
}

edited Sep 1, 2017 at 9:51

answered Sep 1, 2017 at 6:39

Arg0n

8,4532 gold badges26 silver badges39 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

CruelEngine Over a year ago

how can i use the above method to do something like :

for(let i=0; i < this.sudentDetails.length; i++){    this.sudentMap[studentDetails[i].id].name = this.studentDetails[i].name  }

?

AngularChef Over a year ago

The syntax you're mentioning is only for iterating on arrays. In this example studentDetails is an object. Use the following syntax to iterate on the properties of an object : for (var prop in obj) { console.log(obj.${prop} = ${obj[prop]}); }

Arg0n Over a year ago

@CruelEngine I think your question is wrong if you want to be able to do studentDetails[i] and not studentDetails[studentId]. That would indicate an Array instead of an Object. Instead studentMap would be the Object that studentDetails is in my answer. studentDetails would simply be of type Student[].

miken32 · Accepted Answer · 2022-10-19 00:59:55Z

2

First Add a studetId to the interface :

export interface Student {
name : String;
section:String;
phoneNumber:String;
studentID : number;
 }

Then create a map of studentId with the student detail

  students : Student[];
  student1 : Student;

  var studentMap = new Map();

  this.students  = [
  {name : "abc", section :'A', phoneNumber : '123',studentID : 101 },
  {name : "xyz", section :'B', phoneNumber : '456',studentID : 102 },
  {name : "mno", section :'C', phoneNumber : '789',studentID : 103 },

    ];

 for (var item of this.students){
  studentMap.set (item.studentID ,item);
 }

 this.student1 = studentMap.get(101);

Please see this (Plunkr I have created )

edited Oct 19, 2022 at 0:59

miken32

42.5k16 gold badges127 silver badges177 bronze badges

answered Sep 1, 2017 at 7:13

KIA

1922 silver badges9 bronze badges

Collectives™ on Stack Overflow

Creating a an Object of an Object Angular 4

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related