What is the method for accessing the string value of a component's input attribute binding in Angular 2?

Question

What is the method for accessing the string value of a component's input attribute binding in Angular 2?

In my Angular2 application, I have a straightforward form input component with an @Input binding pointing to the attribute [dataProperty]. The [dataProperty] attribute holds a string value of this format:

[dataProperty]="modelObject.childObj.prop"

. The modelObject is a model that is common throughout the application. This @Input attribute allows me to pass the model from a parent component to my <custom-text-input> component, where it is then connected by [ngModel] to the nested component's input.

Everything functions as expected in my controller; when I access this.dataProperty, I get the value on the model that the input binds to. However, I'm struggling to figure out how to retrieve the exact string passed to [dataProperty] from the template.

Component:

@Component{
    selector: "custom-text-input",
    template: "<input type="text" [ngModel]="dataProperty"></input>
}

export Class customInputComponent implements OnInit {
    @Input() dataProperty: string;

    /**
       Example of modelObject: { detail: { name: "Cornelius" } }
       (^^^ would come from the parent component ^^^)
    */

    constructor() {}

}

Use Case:

<div class=wrapper>
    <custom-text-input [dataProperty]="modelObject.detail.name">
    </custom-text-input>
</div>

When I try to access this.DataProperty in the component controller, it returns "Cornelius". Is there a way to access the string literal so I can also capture the "modelObject.detail.name" string from my controller?

angular typescript

Answer 1

Answer №1

If I were to create a key-value pair for the property and its name, I would pass them in together like this:

<div class="container">
    <custom-input [dataPair]="{modelObject.details}">
    </custom-input>
</div>

Then, to access the property name, I would implement it in the following way:

@Component({
    selector: "custom-input",
    template: "<input type='text' [ngModel]='dataPair'></input>"
})
export class CustomInputComponent {

    propertyName;

    private _dataPair;
    
    @Input()
    set dataPair(keyValuePair) {
        this._dataPair = Object.values(keyValuePair)[0];
        this.propertyName = Object.keys(keyValuePair)[0];
    }
    
    get dataPair() {
        console.log("The property name is: " + this.propertyName);
        return this._dataPair;
    }

}

I hope this explanation is useful!

Answer 2

If I were to create a key-value pair for the property and its name, I would pass them in together like this:

<div class="container">
    <custom-input [dataPair]="{modelObject.details}">
    </custom-input>
</div>

Then, to access the property name, I would implement it in the following way:

@Component({
    selector: "custom-input",
    template: "<input type='text' [ngModel]='dataPair'></input>"
})
export class CustomInputComponent {

    propertyName;

    private _dataPair;
    
    @Input()
    set dataPair(keyValuePair) {
        this._dataPair = Object.values(keyValuePair)[0];
        this.propertyName = Object.keys(keyValuePair)[0];
    }
    
    get dataPair() {
        console.log("The property name is: " + this.propertyName);
        return this._dataPair;
    }

}

I hope this explanation is useful!

Answer 3

Answer №2

It is technically feasible to achieve this task, but it requires thinking outside the box. Keep in mind that the element containing the dataProperty is essentially just an HTML node.

<custom-text-input [dataProperty]="modelObject.detail.name">

Unfortunately, I'm not currently able to provide you with a sample demonstration. However, you could easily obtain a reference to the components HTML by using Angular's viewReference in your component and then querying the attribute on it. A rough pseudo code example would be:

 let myString = viewref.nativeElement.getAttribute('[dataProperty]')

While I haven't personally tested this method yet, there shouldn't be any reason why it wouldn’t work as intended.

Answer 4

It is technically feasible to achieve this task, but it requires thinking outside the box. Keep in mind that the element containing the dataProperty is essentially just an HTML node.

<custom-text-input [dataProperty]="modelObject.detail.name">

Unfortunately, I'm not currently able to provide you with a sample demonstration. However, you could easily obtain a reference to the components HTML by using Angular's viewReference in your component and then querying the attribute on it. A rough pseudo code example would be:

 let myString = viewref.nativeElement.getAttribute('[dataProperty]')

While I haven't personally tested this method yet, there shouldn't be any reason why it wouldn’t work as intended.

Answer 5

Answer №3

Regrettably, angular 2 utilizes the default method of converting an Object to a string, resulting in the display of [object Object] in the DOM. This limitation prevents extracting further information.

Furthermore, the object lacks awareness of its parent object. For more insights, refer to: Access parent's parent from javascript object

To address this issue, consider implementing Somo's solution: assign the value as a property within an object. The property name should correspond to the string literal, while the property value holds the actual data.

Illustrative Example:

<div class="container">
    <custom-text-input [dataProperty]="{'modelObject.detail.name': modelObject.detail.name}">
    </custom-text-input>
</div>

Component Definition:

@Component{
    selector: "custom-text-input",
    template: "<input type='text' [ngModel]='actualValue'></input>"
}

export Class customInputComponent implements OnInit {
    @Input() dataProperty: Object;
    actualValue: string;

    ngOnInit() { 
        console.log( Object.keys( dataProperty )[0] );
        console.log( Object.values( dataProperty )[0] );
        this.actualValue = Object.values( dataProperty )[0];
    }    
}

Answer 6

Regrettably, angular 2 utilizes the default method of converting an Object to a string, resulting in the display of [object Object] in the DOM. This limitation prevents extracting further information.

Furthermore, the object lacks awareness of its parent object. For more insights, refer to: Access parent's parent from javascript object

To address this issue, consider implementing Somo's solution: assign the value as a property within an object. The property name should correspond to the string literal, while the property value holds the actual data.

Illustrative Example:

<div class="container">
    <custom-text-input [dataProperty]="{'modelObject.detail.name': modelObject.detail.name}">
    </custom-text-input>
</div>

Component Definition:

@Component{
    selector: "custom-text-input",
    template: "<input type='text' [ngModel]='actualValue'></input>"
}

export Class customInputComponent implements OnInit {
    @Input() dataProperty: Object;
    actualValue: string;

    ngOnInit() { 
        console.log( Object.keys( dataProperty )[0] );
        console.log( Object.values( dataProperty )[0] );
        this.actualValue = Object.values( dataProperty )[0];
    }    
}

Answer 7

Answer №4

Update

Seems like the query revolves around displaying the name of the variable rather than its value. Unfortunately, that cannot be done.

To retrieve the value from the controller:

export Class customInputComponent implements OnInit {
    @Input() dataProperty: string; 

    constructor() {
       console.log(this.dataProperty) // will show modelObject.childObj.prop
    }

}

If you are referring to Interpolation, use this method:

{{dataProperty}} <input type="text" [ngModel]="dataProperty"></input>

For more details, check out:

https://angular.io/docs/ts/latest/guide/template-syntax.html

Answer 8

Update

Seems like the query revolves around displaying the name of the variable rather than its value. Unfortunately, that cannot be done.

To retrieve the value from the controller:

export Class customInputComponent implements OnInit {
    @Input() dataProperty: string; 

    constructor() {
       console.log(this.dataProperty) // will show modelObject.childObj.prop
    }

}

If you are referring to Interpolation, use this method:

{{dataProperty}} <input type="text" [ngModel]="dataProperty"></input>

For more details, check out:

https://angular.io/docs/ts/latest/guide/template-syntax.html

What is the method for accessing the string value of a component's input attribute binding in Angular 2?

Answer №1

Answer №2

Answer №3

Answer №4

Similar questions

Angular fails to detect newly added component

Strategies for modifying the bound value in Angular with an observable object

Angular 2 fails to identify any modifications

What steps should I take to enable the camera view in ngx-scanner?

Properly incorporating a git+https dependency

Can you explain the variance between Next.js and Create React App?

Is it possible to modify the authenticated user ID right before its creation in Firebase, especially when the user is being created via the Facebook provider?

Encountering an issue with resolving parameters for the DecimalPipe in ngBootstrap/Angular2

What are some ways to incorporate inline TypeScript Annotations into standard JavaScript code?

Encountered an Angular 2 error: NullInjectorError - Http provider not found

Using Angular to Apply a Custom Validation Condition on a FormGroup Nested Within Another FormGroup

Encountering issue when attempting to reset stepper component in angular

AngularJS and TypeScript encountered an error when trying to create a module because of a service issue

Error handling in Angular is not properly managing the custom exception being thrown

During the compilation process, Angular could not locate the exported enum

Sign up for an observable within an observable

Unleash the power of zod by seamlessly accessing both parameters and queries

Updating the background color of the side menu in Ionic 4

Creating an application using AngularJS 4 and the Express generator

TypeScript and Express create a powerful array combination capability within the type system