Crafting a model for arrays of objects - a guide to perfection

Question

Crafting a model for arrays of objects - a guide to perfection

Why am I experiencing errors in the console when trying to set the API return to a variable? How can this issue be resolved?

This is my TypeScript code:

public myData = new myDataModel();

getData(){
    this.myCoolService.getDataAPI()
      .subscribe((res) => {
     this.myData = res['financialInformationBean'][0];
});
}

This is what my API returns:

{ 
   "code":0,
   "financialInformationBean":[ 
      { 
         "name":{ 
            "value":"abc"
         },
         "color":{ 
            "value":"green"
         }
      }
   ]
}

This is my model:

export class myDataModel {
  name: Value;
  color: Value;
}

export interface Value {
  value: string;
}

Here is how it appears in my HTML:

<span>{{ myData.name.value }}</span>

The console outputs:

WalletComponent.html:30 ERROR TypeError: Cannot read property 'value' of undefined

I have also tried this in my HTML, which did not show any errors but displayed [Object] [Object] on my page:

<span>{{ myData.name}}</span>

arrays angular typescript object model

Answer 1

Answer №1

If it were up to me, I would recommend utilizing TypeScript's interfaces instead of classes in your codebase. It seems redundant to mix both classes and interfaces for type definitions, especially when you already grasp the concept of interfaces.

You can define the interface for myData as follows:

export interface myDataModel {
  name: Value;
  color: Value;
}

export interface Value {
  value: string;
}

In your component.ts file, make sure to declare and use the defined interface like so:

myData: myDataModel;

getData(){
  this.myCoolService.getDataAPI().subscribe((res) => {
     this.myData = res['dataBean'][0];
  });
}

Moreover, in your component.html template, remember to employ the elvis operator or the safe navigation operator. This is crucial due to the asynchronous nature of HTTP requests which might leave myData undefined initially. Using the safe navigation operator will prevent any rendering errors.

<span>{{ myData?.name.value }}</span>

Answer 2

If it were up to me, I would recommend utilizing TypeScript's interfaces instead of classes in your codebase. It seems redundant to mix both classes and interfaces for type definitions, especially when you already grasp the concept of interfaces.

You can define the interface for myData as follows:

export interface myDataModel {
  name: Value;
  color: Value;
}

export interface Value {
  value: string;
}

In your component.ts file, make sure to declare and use the defined interface like so:

myData: myDataModel;

getData(){
  this.myCoolService.getDataAPI().subscribe((res) => {
     this.myData = res['dataBean'][0];
  });
}

Moreover, in your component.html template, remember to employ the elvis operator or the safe navigation operator. This is crucial due to the asynchronous nature of HTTP requests which might leave myData undefined initially. Using the safe navigation operator will prevent any rendering errors.

<span>{{ myData?.name.value }}</span>

Crafting a model for arrays of objects - a guide to perfection

Answer №1

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