Angular Components Interaction Methods – A Quick Study

Ravi Chandhar P B

Author

April 17, 2020

Introduction – A Brief Into Angular Components Interaction Methods

Angular is a popular front-end framework that allows developers to create complex, dynamic web applications. One of the key features of Angular is its ability to facilitate communication between components often known as angular interaction between components. In this quick study, we will explore the different Angular components interaction methods.

In all the calculations done manually or programmatically, the data collected gets shared and evaluated in a particular process to attain certain end results. Across sectors sharing of data plays a vital role in computing end solutions. Now, let’s get into a comprehensive view of how the data get shared among multiple components in an Angular application. Even before getting started with the Angular Project, is important to a clear understanding of the key concept of Data Sharing. In case of having multiple components in your angular application and to communicate between the components, then Angular provides you some features and angular components interaction methods. Hence, in this section lets get a study on the different angular components interaction methods used for sharing data between the angular components.

Angular Components Interaction Methods

Data sharing between the angular components is possible with the following ways,

• Sharing Data from Parent to Child:  @Input
• Sharing Data from Child to Parent:  @ViewChild
• Sharing Data from Child to Parent:  @Output & EventEmitter 
• Sharing Data Between Various Components:  Service

Sharing Data from Parent to Child:  @Input

Firstly, parent to child component communication in angular provides a decorator called @Input decorator which can be used to pass data from Parent to Child. This is one of the most common methods of sharing data from Parent to Child in Angular application. Now, let’s see the working of the @Input decorator in the following snippets,

# calibraint-parent.component.ts

# calibraint-child.component.ts

Sharing Data from Child to Parent:  @ViewChild

Angular provides this  @ViewChild() decorator which can be used to inject one component to another. Now, this is made possible by giving the parent access to its attributes and functions. Also, to be noted that the Child component gets available only after the view gets initialized. So, we need to implement the AfterViewInit lifecycle hook to get the data from the child.  Now, let’s see the working of the @ViewChild decorator in the following snippets,

# calibraint-parent.component.ts

# calibraint-child.component.ts

Sharing Data from Child to Parent:  @Output & EventEmitter

The @Output decorator allows marking a class field as an output property and supplies configuration metadata.

In this method, the child component will emit the data, which will be received by the parent component. Firstly, if we need to send data from the child to the parent, then it is required to emit the data from the child. To make it function so, we need to create a function in the parent to receive the message and set it equal to the variable of the message. The @Output decorator now allows declaring a message event variable in the child. So, now the parent can subscribe to this message event that the child component emits and then executes the receive message function whenever this event occurs.

This ideal condition and this approach are helpful when you want to share some data on some events like button clicks, users and other form-related events.

# calibraint-parent.component.ts

# calibraint-child.component.ts

Sharing Data Between Various Components – Angular Component To Component Communication:

Component to component communication in angular has Service which is class that holds the data or functions based on the application’s need and also stores the logic in the file, this allows us to reuse the code with the different components when it requires. In the service, we create a private BehaviorSubject that holds the current value of the message. Then, we have to define a current message variable to handle this data stream as an observable that will be used by the components. Lastly, we have to create a function that calls next on the BehaviorSubject to change its value.

# calibraint-data.service.ts

Components of the parent, child, and sibling will receive the same values. We inject the CalibraintDataService into the constructor, then subscribe to the observable current message and set its value equal to the variable message.

Now if we create a function in any of these components which changes the message value. When the new data is executed this function will automatically transmit it to all other components.

# calibraint-parent.component.ts

# calibraint-sibling.component.ts

Conclusion

In conclusion, Angular offers various ways for angular components interaction methods such as Input/Output binding, ViewChild/ViewChildren, and Services. Input/Output binding is a simple and effective way for a parent component to pass data and events to its child components, while ViewChild/ViewChildren provides a way for components to access child components directly. Services, on the other hand, offer a centralized and reusable way for components to share data and logic across an angular web application development. By understanding these methods, developers can create more efficient and scalable applications with Angular. Ultimately, the choice of which method to use depends on the specific needs of the application and the developers’ preference.

In this post, it is depicted on how to share data between parent and child components using @Input(), @Output and EventEmitter and also on the methods to share data between different components. Data sharing is a very important concept, and everybody requires sharing data between the application components. Hope you had an insightful overview of the data sharing concept in angular components interaction methods. 

Reference:- https://angular.io/docs

Credits:- https://carbon.now.sh/

Ravi Chandhar P B

Author

17 Apr 2020

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