Set an interface to null within Angular 4

Question

Set an interface to null within Angular 4

I've created an interface in Angular 4 called StatusDetail:

interface StatusDetail {
    statusName: string,
    name: string
}

Next, I assigned some values to it within an Angular component:

//Angular Component

export class EditComponent implements OnInit{
         statusDetail: StatusDetail;
         ngOnInit() {
           this.statusDetail.statusName = 'text Status';
           this.statusDetail.name= 'text Name';
         }
     }

Now, I want to reset the statusDetail object to null using a method:

SetNull() { 
           this.statusDetail = null
         }

Unfortunately, when attempting to set it to null, I get the following error:

Type null is not assignable to type StatusDetail

How can I resolve this issue?

angular typescript interface

Answer 1

Answer №1

To properly define the variable statusDetail, it is recommended to declare it as type StatusDetail | null:

export class EditPage implements OnInit {
     statusDetail: StatusDetail | null;
    
     ngOnInit() {
       this.statusDetail.statusName = 'active';
       this.statusDetail.name = 'John Doe';
     }
 }

Answer 2

To properly define the variable statusDetail, it is recommended to declare it as type StatusDetail | null:

export class EditPage implements OnInit {
     statusDetail: StatusDetail | null;
    
     ngOnInit() {
       this.statusDetail.statusName = 'active';
       this.statusDetail.name = 'John Doe';
     }
 }

Answer 3

Answer №2

If you need to reset or initiate your interface, follow these steps.

this.interfaceStatus = <InterfaceStatus>{};

By doing this, the object will be set back to its default value. You also have the option to set it as undefined instead of null. Why not take advantage of that?

this.interfaceStatus = undefined;

Answer 4

If you need to reset or initiate your interface, follow these steps.

this.interfaceStatus = <InterfaceStatus>{};

By doing this, the object will be set back to its default value. You also have the option to set it as undefined instead of null. Why not take advantage of that?

this.interfaceStatus = undefined;

Answer 5

Answer №3

Since you have already established the interface with those characteristics, it would be illogical to assign null to your object.

If your intention is to restore the default values, why not simply make them empty?

SetEmpty() { 
  this.statusDetail = {
    statusName: '',
    name: ''
  }
}

If you wish to validate this condition in the HTML code, you could create a new private function specifically for that:

isStatusDetailValid(): boolean {
  return this.statusDetail.statusName && this.statusDetail.name
}

and

*ngIf="isStatusDetailValid()"

Answer 6

Since you have already established the interface with those characteristics, it would be illogical to assign null to your object.

If your intention is to restore the default values, why not simply make them empty?

SetEmpty() { 
  this.statusDetail = {
    statusName: '',
    name: ''
  }
}

If you wish to validate this condition in the HTML code, you could create a new private function specifically for that:

isStatusDetailValid(): boolean {
  return this.statusDetail.statusName && this.statusDetail.name
}

and

*ngIf="isStatusDetailValid()"

Answer 7

Answer №4

To assign null to an interface value, use the syntax {} as any

nullValue(){
 this.interfaceVariable = {} as any
}

Answer 8

To assign null to an interface value, use the syntax {} as any

nullValue(){
 this.interfaceVariable = {} as any
}

Set an interface to null within Angular 4

Answer №1

Answer №2

Answer №3

Answer №4

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