Cannot read property 'push' of undefined Angular/Typescript

Question

I'm trying to add an array of Funcionarios objects into a Equipa object, but when i try to push a new Funcionarios it pops and this error TypeError: Cannot read property 'push' of undefined, i have gone over the code several times and initialized all variables, but it keeps always giving me the same error.

export class Funcionarios {
    id : Number;
    codFunc: Number;
    nomeFunc: string;

    constructor(codFunc: Number, nomeFunc: string) {
        this.codFunc = codFunc;
        this.nomeFunc = nomeFunc;
    }
}

export class Equipa {
    id : Number;
    codEquipa: Number;
    nomeEquipa: string;
    ocorFuncs: Funcionarios[] = [];

    constructor(id : Number, codEquipa: Number, nomeEquipa: string, funcs: Funcionarios[]) {
        this.id = id;
        this.codEquipa = codEquipa;
        this.nomeEquipa = nomeEquipa;
        this.ocorFuncs = funcs;
    }
}

export class TestComponent implements OnInit {

    equipa: Equipa = new Equipa(null, null, null, null);

    ngOnInit() {
        this.equipa.ocorFuncs.push(new Funcionarios(1, "qwe"));
        this.equipa.ocorFuncs.push(new Funcionarios(2, "asd"));
        this.equipa.ocorFuncs.push(new Funcionarios(3, "zxc"));
    }
}

try pushing in ngAfterViewInit instead of ngOnInit

Luca Taccagni
– Luca Taccagni

2018-03-19 13:27:06 +00:00
Commented Mar 19, 2018 at 13:27 — Luca Taccagni
– Luca Taccagni, Commented Mar 19, 2018 at 13:27
@Luca, sorry but it's not the answer

Eliseo
– Eliseo

2018-03-19 13:52:49 +00:00
Commented Mar 19, 2018 at 13:52 — Eliseo
– Eliseo, Commented Mar 19, 2018 at 13:52
equipa: Equipa = new Equipa(null, null, null, []);

Eliseo
– Eliseo

2018-03-19 13:54:09 +00:00
Commented Mar 19, 2018 at 13:54 — Eliseo
– Eliseo, Commented Mar 19, 2018 at 13:54
@Eliseo yes, right! My misunderstanding

Luca Taccagni
– Luca Taccagni

2018-03-19 15:48:40 +00:00
Commented Mar 19, 2018 at 15:48 — Luca Taccagni
– Luca Taccagni, Commented Mar 19, 2018 at 15:48

Kraken · Accepted Answer · 2018-03-19 13:39:46Z

1

Okay, so you see what you are truing to do right now.

You want to push value to the null, null have no push method. if you change this declaration line to

equipa: Equipa = new Equipa(null, null, null, []);

it will work fine, checked on stackblitz

edited Mar 19, 2018 at 13:39

answered Mar 19, 2018 at 13:25

Kraken

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Comments

Titian Cernicova-Dragomir · Accepted Answer · 2018-03-19 13:27:54Z

0

The constructor for Equipa assigns ocorFuncs with whatever comes from the parameter funcs which in your case is null, and thus overrides the value you initialize the field with. You should check if the parameter is null and leave the default value if the parameter is null:

export class Equipa {
    id : Number;
    codEquipa: Number;
    nomeEquipa: string;
    ocorFuncs: Funcionarios[] = [];

    constructor(id : Number, codEquipa: Number, nomeEquipa: string, funcs: Funcionarios[]) {
        this.id = id;
        this.codEquipa = codEquipa;
        this.nomeEquipa = nomeEquipa;
        this.ocorFuncs = funcs || this.ocorFuncs;
    }
}

answered Mar 19, 2018 at 13:27

Titian Cernicova-Dragomir

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Comments

Ric · Accepted Answer · 2018-03-19 13:28:55Z

0

You create your Equipa object like so:

new Equipa(null, null, null, null);

The fourth argument, to initialize ocorFuncs is passed as null so:

this.equipa.ocorFuncs.push(new Funcionarios(3, "zxc"))

is invoking push on an object that has not been initialised correctly.

answered Mar 19, 2018 at 13:28

Ric

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Comments

Ivan Mladenov · Accepted Answer · 2018-03-19 13:29:19Z

0

You are initializing your equipa with null values. So after calling new Equipa(null, null, null, null)

it is setting them inside the constructor as null

this.ocorFuncs = funcs;

try initializing it with an empty array

equipa: Equipa = new Equipa(null, null, null, []);

answered Mar 19, 2018 at 13:29

Ivan Mladenov

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