GET requests in Angular - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the HttpClient module needed for GET requests.

Angular

import { HttpClientModule } from '@angular/common/http';

@NgModule({
  imports: [[1]]
})
export class AppModule {}

Drag options to blanks, or click blank then click option'

AHttpGetModule

BHttpModule

CHttpClientModule

DHttpRequestModule

Attempts:

3 left

💡 Hint

Common Mistakes

Using HttpModule which is deprecated.

Trying to import a non-existing module like HttpGetModule.

You need to import HttpClientModule to use Angular's HTTP client for GET requests.

2fill in blank

medium

Complete the code to inject HttpClient into the constructor for making GET requests.

Angular

import { HttpClient } from '@angular/common/http';

export class DataService {
  constructor(private [1]: HttpClient) {}
}

Drag options to blanks, or click blank then click option'

AhttpClient

BHttpClient

Chttp

Dclient

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name HttpClient as the variable name (uppercase).

Using unrelated names like 'client' without context.

The variable name for the injected HttpClient is usually httpClient or similar. It must be a valid identifier.

3fill in blank

hard

Fix the error in the GET request method to correctly call HttpClient's get function.

Angular

getData() {
  return this.httpClient.[1]('https://api.example.com/data');
}

Drag options to blanks, or click blank then click option'

Arequest

Bfetch

Cpost

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fetch' instead of 'get'.

Using 'post' which is for sending data, not retrieving.

The correct method to make a GET request with HttpClient is get.

4fill in blank

hard

Fill both blanks to subscribe to the GET request and log the response.

Angular

this.httpClient.get('https://api.example.com/data').[1](response => {
  console.[2](response);
});

Drag options to blanks, or click blank then click option'

Asubscribe

Blog

Cerror

Dthen

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'then' which is for Promises, not Observables.

Using 'console.error' instead of 'console.log' for normal output.

Use subscribe to listen to the Observable returned by get, and console.log to print the response.

5fill in blank

hard

Fill all three blanks to create a GET request with typed response and handle errors.

Angular

this.httpClient.get<[1]>('https://api.example.com/data').subscribe({
  next: data => this.data = data,
  error: err => this.[2] = err.message,
  complete: () => console.[3]('Request complete')
});

Drag options to blanks, or click blank then click option'

ADataType

BerrorMessage

Clog

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-existent type like 'DataType' without defining it.

Trying to use 'console.error' for completion message.

Use any as a generic type if no specific type is defined. Store error message in errorMessage and log completion with console.log.

Practice

1. What is the main purpose of a GET request in Angular's HttpClient?

easy

A. To update existing data on the server

B. To send new data to the server

C. To delete data from the server

D. To retrieve data from a server without changing it

Solution

1. Step 1: Understand GET request purpose

   GET requests are used to ask the server to send data without modifying it.

2. Step 2: Compare with other HTTP methods

   POST sends new data, DELETE removes data, PUT/PATCH updates data, so they are not GET.

3. Final Answer:

   To retrieve data from a server without changing it -> Option D

4. Quick Check:

   GET = retrieve data [OK]

Hint: GET always fetches data without changing it [OK]

Common Mistakes:

• Confusing GET with POST or DELETE
• Thinking GET modifies server data
• Using GET to send data in the request body

2. Which of the following is the correct way to make a GET request using Angular's HttpClient?

easy

A. this.http.get('url').subscribe(data => console.log(data));

B. this.http.post('url').subscribe(data => console.log(data));

C. this.http.delete('url').subscribe(data => console.log(data));

D. this.http.put('url').subscribe(data => console.log(data));

Solution

1. Step 1: Identify HttpClient method for GET

   The method to fetch data is get() on HttpClient.

2. Step 2: Check syntax with subscribe

   Using subscribe handles the asynchronous response correctly.

3. Final Answer:

   this.http.get('url').subscribe(data => console.log(data)); -> Option A

4. Quick Check:

   HttpClient.get() + subscribe = correct GET syntax [OK]

Hint: Use http.get() with subscribe to fetch data [OK]

Common Mistakes:

• Using post(), delete(), or put() instead of get()
• Forgetting to subscribe to the observable
• Calling get() without parentheses

3. What will be logged to the console when this Angular code runs?

this.http.get('https://api.example.com/items').subscribe(data => console.log(data));

medium

A. The data received from the API endpoint

B. An error message because subscribe is missing

C. Nothing, because get() does not return data

D. A syntax error due to wrong method usage

Solution

1. Step 1: Understand HttpClient.get() behavior

   The get() method returns an observable that emits the data from the API.

2. Step 2: Effect of subscribe()

   Calling subscribe() listens to the observable and runs the callback with the data, logging it.

3. Final Answer:

   The data received from the API endpoint -> Option A

4. Quick Check:

   subscribe logs API data [OK]

Hint: subscribe callback logs the fetched data [OK]

Common Mistakes:

• Assuming get() returns data directly without subscribe
• Thinking subscribe is optional
• Confusing observable with promise

4. Identify the error in this Angular GET request code:

this.http.get('https://api.example.com/data').subscribe(data => this.data = data);

Assuming this.http is properly injected and data is a class property.

medium

A. GET request URL is invalid

B. HttpClient is not imported

C. Missing error handling in subscribe

D. subscribe callback uses wrong arrow function syntax

Solution

1. Step 1: Check syntax and usage

   The get() call and subscribe syntax are correct, and this.http is assumed injected.

2. Step 2: Identify missing best practice

   No error handling is provided in subscribe, which can cause silent failures.

3. Final Answer:

   Missing error handling in subscribe -> Option C

4. Quick Check:

   Always add error handling in subscribe [OK]

Hint: Always handle errors in subscribe to catch failures [OK]

Common Mistakes:

• Ignoring error callback in subscribe
• Assuming URL is invalid without checking
• Confusing arrow function syntax

5. You want to load a list of users from an API and display them in your Angular component. Which approach correctly combines GET request and updating the component's state?

hard

A. Call this.http.post('api/users').subscribe(users => this.users = users); in constructor

B. Use this.http.get('api/users').subscribe(users => this.users = users); in ngOnInit

C. Assign this.users = this.http.get('api/users'); directly without subscribe

D. Use this.http.delete('api/users').subscribe(users => this.users = users); in ngOnInit

Solution

1. Step 1: Choose correct HTTP method and lifecycle hook

   GET is used to fetch data; ngOnInit is the right place to load data after component creation.

2. Step 2: Use subscribe to update component state

   Subscribe receives data asynchronously and assigns it to this.users for display.

3. Final Answer:

   Use this.http.get('api/users').subscribe(users => this.users = users); in ngOnInit -> Option B

4. Quick Check:

   GET + subscribe + ngOnInit = correct pattern [OK]

Hint: Load data in ngOnInit with http.get() and subscribe [OK]

Common Mistakes:

• Using POST or DELETE instead of GET
• Assigning observable directly without subscribe
• Loading data in constructor instead of ngOnInit