How to Fetch Data from a JSON File by ID in Angular

Описание: Discover how to retrieve specific vehicle data by ID from a JSON file in Angular, using best practices for caching and error handling.
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This video is based on the question https://stackoverflow.com/q/73525540/ asked by the user 'k0uva' ( https://stackoverflow.com/u/15051978/ ) and on the answer https://stackoverflow.com/a/73525988/ provided by the user 'Pankaj Parkar' ( https://stackoverflow.com/u/2435473/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Fetch Data from a JSON File by ID in Angular

As you develop your Angular applications, one common requirement is to fetch specific data from a JSON file. In this post, we'll address a particular situation: how to retrieve information about a specific vehicle from a JSON file based on its ID. Our example revolves around a vehicle shop app, where we display a list of cars and want to show the details of each car when selected.

The Problem: Accessing Vehicle Details by ID

In the context of our vehicle shop app, the main challenge is to extract data for a single vehicle when given its ID. You've set up a service that fetches all car data from a cars.json file, but now you want to extend that functionality to access details of a specific car when the user selects one from the list.

Let's examine the existing setup: you have a car.service.ts that retrieves all cars, and a car-detail.component.ts where you need to load the specifics of a car based on ID.

The Solution: Implementing Caching and Data Retrieval

To solve this issue, we will implement local caching using the shareReplay operator and create a method to retrieve a car by its ID.

Step 1: Modify the Car Service

First, we need to modify our CarService for caching the vehicle data upon initial retrieval. This mechanism will ensure that we don’t repeatedly make HTTP calls to fetch the same data.

Here's how to adjust the car.service.ts:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Retrieve Vehicle Details by ID in the Component

Now that you have set up the service, you can go to your car-detail.component.ts and use the new getCarById method to fetch a single car's details based on the provided ID.

Modify your component's class as follows:

[[See Video to Reveal this Text or Code Snippet]]

Key Takeaways

Caching Data: Using the shareReplay(1) operator efficiently caches the result of your HTTP request, reducing redundant calls and optimizing data retrieval.

Finding an Item: The find method is handy for locating a specific item in an array based on its ID, making your code efficient and clean.

Error Handling: It's crucial to implement error handling to gracefully manage potential failures when fetching data.

By following these steps, you can easily retrieve a specific vehicle's information by ID in your Angular vehicle shop application. Happy coding!