TS: Definition of custom object array

Question

This is my array definition (probably there is a problem. I wanted to say that this array will be an array of custom objects):

const records: {LicencePlate: string, Description: string, 
SetToUse: string, Depot: string, Active: boolean}[] = [];

Then I want to fill it:

  this.grid.gridView.data.forEach(element => {
      records.push(element.LicencePlate, element.Description, element.DateOfStartUse.toLocaleDateString('en-GB'),
      element.Base, element.Active);
    });

I wanted to get something like this - array of objects

[{"Johnny", "Actor", "05/03/2000", "Holywood", true}, 
 {"Kirk", "Musician", "01/06/1999", "California", true}, 
 {"Elvis", "Singer", "15/09/1975", "Mississippi", false}]

But I got only one long array of single values:

["Johnny", "Actor", "05/03/2000", "Holywood", true, 
"Kirk", "Musician", "01/06/1999", "California", true, 
"Elvis", "Singer", "15/09/1975", "Mississippi", false]

Where have I made a mistake?

charlietfl · Accepted Answer · 2018-10-28 20:33:52Z

0

You need to push a new object into the array every iteration.

Something like:

this.grid.gridView.data.forEach(element => {
  // create object for this row
  const o = {
    LicencePlate: element.LicencePlate,
    Description: element.Description,
    /// other properties and values
  }
  // push that object to array
  records.push(o);
});

answered Oct 28, 2018 at 20:33

charlietfl

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score 0 · Accepted Answer · 2018-10-28 20:49:11Z

-edit Oops, this is js and you want ts.. Disregard. I'll leave this here.

In addition to charlietfl's answer, the documentation on <array>.push:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push

arr.push(element1[, ...[, elementN]])

You're wanting to push a single element into an array index at the end,

but you are pushing each field of your element into the array at a new index instead.

charlietfl's answer essentially creates a shallow duplicate of each element, you could alternatively just push the element directly:

let records = []; //or new Array();
//typescript will let you do new Array<Record>(), but not in javascript

this.grid.gridView.data.forEach(element => {
  records.push(element);
});

My implementation of records:

//An implementation of your record object (you apparently already have these, so you don't need it)
class Record {
  constructor (licensePlate) {
    this.licensePlate = licensePlate;
    this.description = description;
    this.setToUse = setToUse;
    this.depot = depot;
    this.active = active;
  }
}

let records = new Array(); //In typescript we can have Array<Record> for typed array, but not in js :(

//I'm creating a test record here because I don't have your gridView code
let rec = new Record("BLAHBLAH", "A record example instance", "some kind of set to use", "a depot", false);

records.push(rec); //Push the record instance|object into the array

//this.grid.gridView.data.forEach(element => {
//  records.push(element.LicencePlate, element.Description, element.DateOfStartUse.toLocaleDateString('en-GB'),
//  element.Base, element.Active);
//});

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