A guide on accessing elements in arrays using Angular

Question

A guide on accessing elements in arrays using Angular

Using the httpModule from an API to retrieve data is my current task. I have included my code snippet below:

async searchMeaning(form: NgForm) {

    const post = {
      word: form.value.inputWord,
      language: form.value.language
    }
    console.log(post);
    if (post.language && post.word) {
       this.output1 = await this.callApi(post); // it displays await has not effect
       console.log(this.output1) // undefined.
    }
  }

   callApi(post) {
    this.http.get('https://api.dictionaryapi.dev/api/v2/entries/'+post.language+'/'+post.word)
    .subscribe((data) => {
      console.log(JSON.parse(JSON.stringify(data)));
      return data;
      
    }, (error : any) => {
      return error
    })
  }

My issue arises when attempting to utilize async and await; an "await has no effect" warning is triggered. Additionally, the variable this.output is being assigned as undefined. How can these issues be resolved? Furthermore, how can I access a variable from the response array provided below?

[
    {
        "word": "hello",
        "phonetics": [
            {
                "text": "/həˈloʊ/",
                "audio": "https://lex-audio.useremarkable.com/mp3/hello_us_1_rr.mp3"
            },
            {
                "text": "/hɛˈloʊ/",
                "audio": "https://lex-audio.useremarkable.com/mp3/hello_us_2_rr.mp3"
            }
        ],
        "meanings": [
            {
                "partOfSpeech": "exclamation",
                "definitions": [
                    {
                        "definition": "Used as a greeting or to begin a phone conversation.",
                        "example": "hello there, Katie!"
                    }
                ]
            },
            {
                "partOfSpeech": "noun",
                "definitions": [
                    {
                        "definition": "An utterance of “hello”; a greeting.",
                        "example": "she was getting polite nods and hellos from people",
                        "synonyms": [
                            "greeting",
                            "welcome",
                            "salutation",
                            "saluting",
                            "hailing",
                            "address",
                            "hello",
                            "hallo"
                        ]
                    }
                ]
            },
            {
                "partOfSpeech": "intransitive verb",
                "definitions": [
                    {
                        "definition": "Say or shout “hello”; greet someone.",
                        "example": "I pressed the phone button and helloed"
                    }
                ]
            }
        ]
    } ]

I am specifically interested in extracting the value of the definition variable from the above array. How can this be achieved?

console image

javascript angular typescript rxjs

Answer 1

Answer №1

I am encountering an issue when using async and await as it states that await has no effect.

This is because await only affects Promises (a JavaScript native type). this.callApi(post) returns a Subscription which is of type RxJS, not a Promise.

In Angular, it is recommended to use Observables over Promises as much as possible. By building up observables with pipes and then subscribing when needed, you gain numerous advantages, especially in complex scenarios. Here's an example of how to handle this:

searchMeaning(form: NgForm) {

    const post = {
      word: form.value.inputWord,
      language: form.value.language
    }
    console.log(post);
    if (post.language && post.word) {
       this.callApi(post).subscribe(x => {
           this.output1 = x;
           console.log(this.output1); // should now have a value
           // additional logic can be implemented here to affect the component state
       });
       // Be aware that code written here executes before the API call.
    }
  }

   callApi(post) {
    this.http.get('https://api.dictionaryapi.dev/api/v2/entries/'+post.language+'/'+post.word)
    .pipe(map(x => {
         // modify x before returning
         return x;
     }));
  }

Furthermore, how do I access a variable from the response array below?

For instance, to access the first definition example, you could use:

x[0]["meanings"][0]["definitions"][0]["example]

. Defining types for easier access is an option but may not be necessary for casual dictionary usage.

Referencing the Angular documentation on Observables or exploring real-world examples of calling APIs with HttpClient can be beneficial.

Answer 2

I am encountering an issue when using async and await as it states that await has no effect.

This is because await only affects Promises (a JavaScript native type). this.callApi(post) returns a Subscription which is of type RxJS, not a Promise.

In Angular, it is recommended to use Observables over Promises as much as possible. By building up observables with pipes and then subscribing when needed, you gain numerous advantages, especially in complex scenarios. Here's an example of how to handle this:

searchMeaning(form: NgForm) {

    const post = {
      word: form.value.inputWord,
      language: form.value.language
    }
    console.log(post);
    if (post.language && post.word) {
       this.callApi(post).subscribe(x => {
           this.output1 = x;
           console.log(this.output1); // should now have a value
           // additional logic can be implemented here to affect the component state
       });
       // Be aware that code written here executes before the API call.
    }
  }

   callApi(post) {
    this.http.get('https://api.dictionaryapi.dev/api/v2/entries/'+post.language+'/'+post.word)
    .pipe(map(x => {
         // modify x before returning
         return x;
     }));
  }

Furthermore, how do I access a variable from the response array below?

For instance, to access the first definition example, you could use:

x[0]["meanings"][0]["definitions"][0]["example]

. Defining types for easier access is an option but may not be necessary for casual dictionary usage.

Referencing the Angular documentation on Observables or exploring real-world examples of calling APIs with HttpClient can be beneficial.

Answer 3

Answer №2

To ensure smooth asynchronous operations, it is recommended to return an observable from the callApi() function and then utilize await on your method:

callApi(post) {
  const sub = new Subject();
  this.http.get('https://api.dictionaryapi.dev/api/v2/entries/'+post.language+'/'+post.word)
    .subscribe((data) => {
      console.log(JSON.parse(JSON.stringify(data)));
      sub.next(data)
      sub.unsubscribe();
    }, (error : any) => {
      sub.error(data);
      sub.unsubscribe();
    })

  return sub.asObservable();
}

this.output1 = await this.callApi(post).pipe(first()).toPromise();

If you prefer not to use .pipe(first()).toPromise(), then ensure that callApi returns a Promise.

Depending on the functionality required for callApi, you can simply return this.http.get() or

this.http.get().pipe(first()).toPromise()

.

Answer 4

To ensure smooth asynchronous operations, it is recommended to return an observable from the callApi() function and then utilize await on your method:

callApi(post) {
  const sub = new Subject();
  this.http.get('https://api.dictionaryapi.dev/api/v2/entries/'+post.language+'/'+post.word)
    .subscribe((data) => {
      console.log(JSON.parse(JSON.stringify(data)));
      sub.next(data)
      sub.unsubscribe();
    }, (error : any) => {
      sub.error(data);
      sub.unsubscribe();
    })

  return sub.asObservable();
}

this.output1 = await this.callApi(post).pipe(first()).toPromise();

If you prefer not to use .pipe(first()).toPromise(), then ensure that callApi returns a Promise.

Depending on the functionality required for callApi, you can simply return this.http.get() or

this.http.get().pipe(first()).toPromise()

.

A guide on accessing elements in arrays using Angular

Answer №1

Answer №2

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