What is the best way to display a loading state while waiting for all Firebase data requests to be fully processed?

Question

What is the best way to display a loading state while waiting for all Firebase data requests to be fully processed?

Hey there! I'm looking for some advice on how to display a loading indicator like this:

https://i.sstatic.net/7luvR.gif

while waiting for my Firebase data to load completely.

I attempted to use

<div *ngIf="!listOfFoodObject">
   <img [src]="https://i.sstatic.net/7luvR.gif" />
</div>

but unfortunately, it didn't work as expected. Can anyone assist me with this?

This is the current Firebase code in my controller:

firebase.database().ref('menu_name').orderByChild('menu_name').once('value',(snapshot)=>{
    snapshot.forEach((snap)=>{
        this.listOfFoodObject.push({
            key: snap.key,
            menu_name:String(snap.val().menu_name).toUpperCase(),
            menu_image:snap.val().menu_image,
            description:snap.val().description
        });
    return false;
    });

});

And here's my <ion-list> view:

<ion-list>
    <ion-item *ngFor="let food of listOfFoodObject">
        <ion-thumbnail item-left (click)="show_item_details(food.menu_name,food.key,food.menu_image,food.description)">
            <img src="{{food.menu_image}}">
        </ion-thumbnail>
        <h2 (click)="show_item_details(food.menu_name,food.key,food.menu_image,food.description)">{{food.menu_name}}</h2>
        <p (click)="show_item_details(food.menu_name,food.key,food.menu_image,food.description)">{{food.description}}</p>
        <p>
            <ion-icon ios="ios-star" md="md-star"></ion-icon>
            3.8
        </p>
        <button ion-button round item-right (click)="show_item_details(food.menu_name,food.key,food.menu_image,food.description)">View sellers</button>
    </ion-item>
</ion-list>

Thanks for any help you can provide!

angular typescript ionic2 loading

Answer 1

Answer №1

let dataPromise = new Promise(function(resolve, reject) {

    // Perform database tasks and request data

    if(data is received) {
        resolve(your data will be returned here);
    }
    else {
        reject(an error will be thrown here);
    }
});

dataPromise.then(function() { 
    // Handle the resolved promise to utilize the data
}).catch(function() {
    // Manage any errors that were rejected
})

The example above illustrates a basic implementation of a promise, which is used to standardize AJAX requests. If you are working with nodejs, angularjs, or similar libraries, there may already be built-in promise functionalities available. Otherwise, you can explore deferred objects as an alternative for promise implementations.

In this code snippet, a promise (dataPromise) is created that can either be resolved (successful data retrieval asynchronously) or rejected. The promise operates in the background until completion, triggering the then method to enable operations on the returned values. This oversimplified explanation should help grasp the concept of promises.

Answer 2

let dataPromise = new Promise(function(resolve, reject) {

    // Perform database tasks and request data

    if(data is received) {
        resolve(your data will be returned here);
    }
    else {
        reject(an error will be thrown here);
    }
});

dataPromise.then(function() { 
    // Handle the resolved promise to utilize the data
}).catch(function() {
    // Manage any errors that were rejected
})

The example above illustrates a basic implementation of a promise, which is used to standardize AJAX requests. If you are working with nodejs, angularjs, or similar libraries, there may already be built-in promise functionalities available. Otherwise, you can explore deferred objects as an alternative for promise implementations.

In this code snippet, a promise (dataPromise) is created that can either be resolved (successful data retrieval asynchronously) or rejected. The promise operates in the background until completion, triggering the then method to enable operations on the returned values. This oversimplified explanation should help grasp the concept of promises.

Answer 3

Answer №2

It seems like in your Firebase code, you've initialized the listOfFoodObject as an empty array.

listOfFoodObject =[];

However, keep in mind that an empty array is considered a "truthy" value. This might be why the *ngIf condition in your HTML code is evaluating to false and not displaying the image:

<div *ngIf="!listOfFoodObject">
   <img [src]="https://i.sstatic.net/7luvR.gif" />
</div>

To fix this issue, it's recommended to initialize the listOfFoodObject as an empty array right before your forEach loop.

Answer 4

It seems like in your Firebase code, you've initialized the listOfFoodObject as an empty array.

listOfFoodObject =[];

However, keep in mind that an empty array is considered a "truthy" value. This might be why the *ngIf condition in your HTML code is evaluating to false and not displaying the image:

<div *ngIf="!listOfFoodObject">
   <img [src]="https://i.sstatic.net/7luvR.gif" />
</div>

To fix this issue, it's recommended to initialize the listOfFoodObject as an empty array right before your forEach loop.

Answer 5

Answer №3

To enhance user experience, consider implementing promises as suggested earlier.

Utilize the code shared by mnemosdev for a smooth process.

One thing to keep in mind is to ensure that the rest of the page remains accessible while displaying a loading icon. This prevents users from getting frustrated if they interact with elements on the page and receive no response.

Create a custom component similar to this example where you can show the loading indicator when making requests and hide it once the operation is complete, regardless of the outcome.

While this may not directly answer your question, it's important information to consider.

Answer 6

To enhance user experience, consider implementing promises as suggested earlier.

Utilize the code shared by mnemosdev for a smooth process.

One thing to keep in mind is to ensure that the rest of the page remains accessible while displaying a loading icon. This prevents users from getting frustrated if they interact with elements on the page and receive no response.

Create a custom component similar to this example where you can show the loading indicator when making requests and hide it once the operation is complete, regardless of the outcome.

While this may not directly answer your question, it's important information to consider.

What is the best way to display a loading state while waiting for all Firebase data requests to be fully processed?

Answer №1

Answer №2

Answer №3

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