Advanced Routing Techniques in Angular: Guards and Resolvers

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Advanced Routing Techniques in Angular: Guards and Resolvers

Routing Techniques in Angular

Angular is recognized as one of the most preferred frameworks for creating robust and dynamic single-page applications (SPAs). One of its standout features is its routing system, which empowers developers to build navigation flows and ensure a smooth user experience. As applications become more intricate, it becomes increasingly important to implement routing techniques that effectively handle various complicated scenarios.

The Importance of Routing in Angular

Routing is the foundation for any SPA as it determines how users navigate within an application, making it a crucial aspect of user experience and application functionality. The angular routing module provides diverse features for defining routes, including lazy loading, child routes, route parameters, and route guards. Among these features, route guards and resolvers play significant roles in controlling and improving the routing process.

Understanding Route Guards

In Angular, route guards serve as mechanisms that allow developers to control access to routes or components within an application. They act as gatekeepers, intercepting and evaluating navigation requests and allowing or preventing navigation.

Angular includes three routes – CanActivate, CanActivateChild, and CanDeactivate. With these routes, developers are flexible to create custom route guards tailored to their requirements.

1) CanActivate: Securing Routes

The CanActivate guard serves as a measure for protecting routes against unauthorized access. It enables developers to set conditions that must be met for users to access specific routes. For example, you can implement authentication checks to ensure authenticated users can enter parts of your application. Therefore, CanActivate is particularly useful for safeguarding routes that necessitate user login.

2) CanActivateChild: Protecting Child Routes

Parallel to CanActivate, the CanActivateChild guard offers protection, but only at the child route level. It proves beneficial when dealing with nested routes, and there is a need to enforce access control on all child routes under a parent route. For instance, an admin section of your application might contain child routes accessible solely by users with admin privileges.

3) CanDeactivate: Confirming Navigation

The role of the CanDeactivate guard comes into play when a user intends to leave a route. It prompts the user for confirmation before navigating away, such as in cases where there are unsaved changes in a form. This guard allows developers to prevent accidental navigation and provides users with a smooth and intuitive experience.

4) Creating Custom Route Guards

While Angular already provides built-in guards, it is also possible to create custom route guards to meet specific requirements. These custom guards can be utilized as classes to implement CanActivate, CanActivateChild, or CanDeactivate interfaces, depending on the requirements. They enable tasks such as checking user roles, verifying permissions, or fetching data before allowing navigation.

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Utilizing Resolvers for Data Retrieval

Alongside route guards, Angular offers another routing feature known as resolvers. Resolvers are employed to fetch data before activating a route to ensure that the necessary data is available when rendering a component. This capability contributes to delivering a user experience by eliminating any delays in displaying views that depend on data.

1) Resolver Interface

In Angular, a resolver is a class that implements the Resolver interface. This interface mandates the implementation of a single method, ‘resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<any> | Promise<any> | any. The purpose of this method is to provide the required data for a given route or component.

2) Use Cases for Resolvers

Resolvers prove beneficial when dealing with situations where routes or components rely on data retrieved from servers or external sources.

  • Use Profiles

In situations when you want to display a user profile page, you can use a resolver to fetch the user data from an API based on their username before showing the profile component.

  • Content Pages

In applications that rely on content, employ resolvers to retrieve content data from a CMS or database, ensuring the content is readily available when navigating to a specific page.

  • Data Driven Components

Components that present data grids or charts fetch data from a server. Resolvers can handle this task by procuring the required data before yielding the component.

3) Ensuring Data Availability

The main advantage of using resolvers is that they guarantee the availability of required data when activating a route. It eliminates the need for checks and loading indicators in your components. Instead, your components can confidently assume that the necessary data is ready for use.

Combining Guards and Resolvers

While route guards and resolvers are powerful individually, they can also be used together to create a comprehensive routing solution. Here’s how you can combine them for a seamless user experience:

1) Authentication with Guards and Data Loading with Resolvers

Imagine a situation where you have a protected route that needs both authentication and the loading of user data, like a dashboard. To ensure that authenticated users can access the route and that their data is ready when they reach the dashboard, you can utilize the CanActivate guard. Additionally, by using a resolver, you can fetch the user’s data before displaying the dashboard component.

2) Permissions and Dynamic Routing

In applications with role-based access control, you can employ route guards to check user permissions and determine if they are allowed to access specific routes. By leveraging resolvers, you can dynamically load data based on the user’s permissions. For instance, an admin dashboard might display data and components depending on whether the user has admin privileges.

3) Handling Complex Data Dependencies

When dealing with components with data dependencies that require API calls or asynchronous operations to fetch data, resolvers come in handy. They orchestrate these operations to ensure all data is available before rendering the component. Route guards can still be utilized to control access to such components, ensuring users only gain access when all required data is ready.

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Important Considerations and Best Practices

While guards and resolvers offer powerful routing capabilities, it’s essential to follow best practices and consider potential challenges when implementing them in your Angular applications:

1) Proper Error Handling

Ensure that your guards and resolvers have error-handling mechanisms. If you encounter problems with data retrieval or authorization, ensure delivery of error messages or redirect users to an error page.

2) Dealing with Asynchronous Operations

Consider that resolvers often involve operations, such as making HTTP requests. Therefore, take advantage of Angular’s ‘async’ pipe to handle the observables returned by resolvers in your templates.

3) Performance Considerations

When using resolvers, it is significant to be mindful of the performance implications when multiple resolvers are used on the route. Consequently, avoid data fetching and optimize performance by employing route reuse strategies.

4) Thorough Testing

It is essential to test guards and resolvers to ensure their best performance. Angular provides testing utilities like ActivatedRouteSnapshot and RouterStateSnapshot for unit testing purposes.


Route guards and resolvers play a significant role as indispensable tools for controlling and enhancing the routing process. They empower developers to implement access control load data and create user experiences even in complex single-page applications. By using route guards, you can ensure that authorized users have access to routes and components.

On the other hand, resolvers help fetch the required data before rendering components, ensuring that your views always have the information. Combining these techniques allows developers to create secure applications driven by data. Integrating these techniques into your projects will undoubtedly contribute to the success and reliability of your applications.

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