I encounter an error message stating "Cannot read property 'push' of undefined" when trying to add an item to a property within an interface

Question

I encounter an error message stating "Cannot read property 'push' of undefined" when trying to add an item to a property within an interface

I have a model defined like this :

    export interface AddAlbumeModel {
    name: string;
    gener: string;
    signer: string;
    albumeProfile:any;
    albumPoster:any;
    tracks:TrackMode[];
}

export interface TrackMode {
    trackNumber: number;
    trackName: string;
    trackProfile: any;
    trackPoster:any;
    trackFile: any;
}

Now, I'm trying to add tracks using the following code :

let addModel = {} as AddAlbumeModel;

for (let index = 0; index < this.addAlbumFG.controls['tracks']['controls'].length; index++) {

 const item= this.addAlbumFG.controls['tracks']['controls'][index]['controls'];

 if(!addModel.tracks){
   addModel.tracks = [];
 }

 addModel.tracks.push({
    trackFile:item.trackFile.value['files'][0],
    trackNumber:item.trackNumber.value,
    trackName:item.trackName.value,
    trackPoster:item.trackPoster.value['files'][0],
    trackProfile:item.trackProfile.value['files'][0]
  })
}

However, I'm encountering the following error message :

ERROR TypeError: Cannot read property 'push' of undefined

Can someone help me find a solution for this issue?

javascript angular typescript

Answer 1

Answer №1

Hey there, the error message you received is because the 'available' variable was not declared as an array:

ERROR TypeError: Cannot read property 'push' of undefined

To fix it, follow these steps:

let addModel = {} as AddAlbumeModel;
addModel.tracks = [];
for (let index = 0; index < this.addAlbumFG.controls['tracks']['controls'].length; 
index++) {

const item= this.addAlbumFG.controls['tracks']['controls'][index]['controls'];

addModel.tracks.push({
trackFile:item.trackFile.value['files'][0],
trackNumber:item.trackNumber.value,
trackName:item.trackName.value,
trackPoster:item.trackPoster.value['files'][0],
trackProfile:item.trackProfile.value['files'][0]
})
}

All set now :)

Answer 2

Hey there, the error message you received is because the 'available' variable was not declared as an array:

ERROR TypeError: Cannot read property 'push' of undefined

To fix it, follow these steps:

let addModel = {} as AddAlbumeModel;
addModel.tracks = [];
for (let index = 0; index < this.addAlbumFG.controls['tracks']['controls'].length; 
index++) {

const item= this.addAlbumFG.controls['tracks']['controls'][index]['controls'];

addModel.tracks.push({
trackFile:item.trackFile.value['files'][0],
trackNumber:item.trackNumber.value,
trackName:item.trackName.value,
trackPoster:item.trackPoster.value['files'][0],
trackProfile:item.trackProfile.value['files'][0]
})
}

All set now :)

Answer 3

Answer №2

The issue arises because the property tracks has not been defined. When working with Typescript, Interfaces are primarily used for type checking purposes only, as they are discarded once the code is converted to JavaScript.

Below are a couple of potential solutions:

Ensure property is initialized before usage

To rectify this, you can initialize the tracks property before attempting to use it.

interface TrackMode {
   // properties
}

interface AddAlbumeModel {
    // other properties
    tracks: TrackMode[];
}

let addModel: AddAlbumeModel = {
    tracks: []
} as AddAlbumeModel;

addModel.tracks.push(...)

Utilize classes instead of interfaces

Since interfaces do not support default values, an alternative approach is to utilize classes and set default values for the tracks property as an empty array.

interface TrackMode {
   // properties
}

class AddAlbumeModel {
    // other properties
    tracks: TrackMode[] = [];
}

const addModel = new AddAlbumeModel()

addModel.tracks.push(...)

Answer 4

The issue arises because the property tracks has not been defined. When working with Typescript, Interfaces are primarily used for type checking purposes only, as they are discarded once the code is converted to JavaScript.

Below are a couple of potential solutions:

Ensure property is initialized before usage

To rectify this, you can initialize the tracks property before attempting to use it.

interface TrackMode {
   // properties
}

interface AddAlbumeModel {
    // other properties
    tracks: TrackMode[];
}

let addModel: AddAlbumeModel = {
    tracks: []
} as AddAlbumeModel;

addModel.tracks.push(...)

Utilize classes instead of interfaces

Since interfaces do not support default values, an alternative approach is to utilize classes and set default values for the tracks property as an empty array.

interface TrackMode {
   // properties
}

class AddAlbumeModel {
    // other properties
    tracks: TrackMode[] = [];
}

const addModel = new AddAlbumeModel()

addModel.tracks.push(...)

I encounter an error message stating "Cannot read property 'push' of undefined" when trying to add an item to a property within an interface

Answer №1

Answer №2

Ensure property is initialized before usage

Utilize classes instead of interfaces

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