Is there a way to retrieve the object property within the subscribe function in order to display the HTML content?

Is there a way for me to update the HTML using the properties obtained within .subscribe? I am aware that .subscribe is asynchronous and therefore returns an undefined value initially, but how can I ensure it waits until the value is resolved? Currently, I am only receiving undefined for the object properties.

Below is my service method where I make the API call to retrieve the data:


fetchCustomers(name: string) Observable<Customer[]> {
    return this.http.get<Customer>('MY URL')
}

And here is the component in which I subscribe to it:

   
customer: any;
name: string;

ngOnInit() {
//this.name = /*code to retrieve the name*/
this.renderCustomer(this.name)
}

renderCustomer(name) {
this.testService.fetchCustomer(name).subscribe(data => {
this.customer = data
})
}

However, when calling the method this.customer, it remains undefined. I need the properties of data to render in my HTML file as shown below:

 
<tr> {{ customer.companyName }} </tr>
<tr> {{ customer.fullName }} </tr>
<tr> {{ customer.Email }} </tr>

How can I modify the line this.customer = data so that it waits for the Observable to be resolved? I have also attempted

this.customer = JSON.parse(JSON.stringify(data))
as mentioned in another discussion, but it did not yield any success.

Answer №1

Great job on your code! Have you considered incorporating a safe navigation operator in your project?

<tr> {{ user?.username }} </tr>
<tr> {{ user?.firstName }} </tr>
<tr> {{ user?.email }} </tr>

Answer №2

To ensure smooth loading of data in HTML, you can utilize the safe navigation operator:

 <tr> {{ customer?.companyName }} </tr>
 <tr> {{ customer?.fullName }} </tr>
 <tr> {{ customer?.Email }} </tr>

If you want to show a loader while waiting for the data to load, consider implementing something like this:

<ng-container ngIf="!customer"> 
  <spinner></spinner>
</ng-container>
<ng-container ngIf="customer"> 
   ...
   <tr> {{ customer.companyName }} </tr>
   <tr> {{ customer.fullName }} </tr>
   <tr> {{ customer.Email }} </tr>
   ...
</ng-container>

Answer №3

If you follow @Sajeetharan's advice or enclose your tr elements in an if statement:

<ng-container *ngIf="customer">
 <tr> {{ customer.companyName }} </tr>
 <tr> {{ customer.fullName }} </tr>
 <tr> {{ customer.Email }} </tr>
</ng-container>

This will ensure that the content is only displayed when the customer object has a value.

Answer №4

You may also utilize the async pipeline

element

client$: Observable<any>;
title: string;

ngOnInit() {
   this.displayClient(this.title)
}

displayClient(title) {
   this.client = this.service.loadClient(title)
})

design

<tr> {{ client.company | async }} </tr>
<tr> {{ client.name | async  }} </tr>
<tr> {{ client.email | async  }} </tr>

Answer №5

To ensure default values of null are set for each property in the customer model interface, you can do so by initializing them like this:

public customer: Customer = { companyName: null, fullName: null, Email: null } 

Then in your HTML:

<tr> {{ customer.companyName }} </tr>
<tr> {{ customer.fullName }} </tr>
<tr> {{ customer.Email }} </tr>

Alternatively, you can use the '?' operator as shown below :

<tr> {{ customer?.companyName }} </tr>
<tr> {{ customer?.fullName }} </tr>
<tr> {{ customer?.Email }} </tr>

Answer №6

If you have both customer and name data coming from subscriptions, consider using rxjs flatMap to chain them together here

customer: any;
name: string;

ngOnInit() {
  this.loadCustomerData();
}

loadCustomerData() {
   this.service.fetchName(/*variable to retrieve the name*/)
    .pipe(
      flatMap((name: string) => {
        this.name = name;
        return this.service.fetchCustomer(name);
      })
    ).subscribe(response => {
       this.customer = response;
    });
}

Answer №7

If you're facing an issue with the HTML itself, you can add a question mark to verify if the object is defined:

 <tr> {{ customer?.companyName }} </tr>

Alternatively, you could also use

*ngIf="customer"
 
on the parent div.

If you need to perform additional actions within your component, you can utilize a callback function for further processing.

your_component.ts

renderCustomer(name) {
      this.testService.fetchCustomer(name).subscribe(data => {
      this.customer = data;
      foo(data);
  })

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