Loop over object's key/value using TypeScript / Angular2

Question

How can I iterate over a Object using TypeScript and being able to access key and value?

My json object looks something like this:

{
    "clients": {
        "123abc": {
            "Forename": "Simon",
            "Surname": "Sample"
        },
        "456def": {
            "Forename": "Charlie",
            "Surname": "Brown"
        }
    }
}

The clients object to be filled is made of client models looking like:

export class ClientModel {
    id:string;
    forename:string;
    surname:string;

    constructor(
        private id:string,
        private forename:string,
        private surname:string
    ) {
        this.id = id;
        this.forename = forename;
        this.surname = surname;
    }
}

Nikos Paraskevopoulos · Accepted Answer · 2016-06-07T11:17:54.993

Given:

var a = {
    "clients": {
        "123abc": {
            "Forename": "Simon",
            "Surname": "Sample"
        },
        "456def": {
            "Forename": "Charlie",
            "Surname": "Brown"
        }
    }
};

class ClientModel {
    constructor(
        private id:string,
        private forename:string,
        private surname:string
    ) {}
}

Here is how to get an array of ClientModel objects:

var clientList: ClientModel[] = Object.getOwnPropertyNames(a.clients)
    .map((key: string) => new ClientModel(key, a.clients[key].Forename, a.clients[key].Surname));

...and here how to get a map from string (id) to ClientModel:

var clientMap: { [key: string]: ClientModel } = Object.getOwnPropertyNames(a.clients)
    .reduce((map: any, key: string) => {
        map[key] = new ClientModel(key, a.clients[key].Forename, a.clients[key].Surname);
        return map;
    }, {});

After the comment from basarat and taking a closer look at Object.keys(), Object.keys is more appropriate for use here than Object.getOwnPropertyNames(). The difference is that the latter returns non-enumerable properties too. It has no practical difference in this particular case, but should make the intent of the code more explicit. Everything else remains the same.

A lot to learn for old school JavaScript developers. Thank you very much! — Sommereder, Jun 06 '16 at 22:21
Very strongly prefer `Object.keys`. Same thing (for most purposes http://stackoverflow.com/a/22658584/390330), simpler and more common in the wild — basarat, Jun 06 '16 at 23:38
@basarat Yes, indeed, `Object.keys` is more appropriate, thank you. — Nikos Paraskevopoulos, Jun 07 '16 at 11:13

Loop over object's key/value using TypeScript / Angular2

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