Using service in the constructor of a MODEL (angular)

Question

So, My goal is to use service in a model constructor because my service use info and method that my constructor could use.

For better understanding, i immagined a user case on the fly. Don't forget it's just an exemple for the problem.

Models

Let's say i've a model with dog info But also, I want the height difference with the breed average.

Class Dog{

id: string;
name: string
breed: string
age: number
height: number
dif_Height: number

Constructor(id, name, breed, age, height){

this.id = id;
this.name = name,
this.breed= breed,
this.age = age,
this.height = height

}
}

Services

By change, in my service, i've a perfect function for it

In my service, all the breed info are stored. And i've function that give me the Height Diff by sending the breed.

 GetbreedDif(breed){

// FIND MY BREED

// CALCUL THE DIF

// 

return  HeightDif;
} 

Now, I want to use this specific function in MY MODELS.

What his the best way to implement it ?

My ideas

- I send the service as parameter

Constructor(id, name, breed, age, height, service){

this.id = id;
this.name = name,
this.breed = breed,
this.age = age,
this.height = height,
this.dif_Height = service.GetbreedDif(breed)

}

But I don't like to send my service this way, and think this is'nt optimal.

- I Recreate the function, using my service info as parameter

Constructor(id, name, breed, age, height, service_breedlist){

this.id = id;
this.name = name,
this.breed = breed,
this.age = age,
this.height = height,
this.dif_Height = this.GetbreedDif(breed, service_breedlist)

}

GetbreedDif(breed, MyServiceList){

// FIND MY BREED

// CALCUL THE DIF

// 

return  HeightDif;
}

Which i found better, but pretty annoying to pass something that is already fixed somehere else, especially if, for some reasons i must create a lot of object.

- Inject the service in the models ?

It's my third idea. But, i'm not sure of the exact implementation and also of the consequence of it.

- Something else ?

Is there any method i did'nt think about and would be good ?

Answer 1

If your service method does not have a state, then using a static method might be the solution here.

// service
export class BreedDiffService {
   static GetBreedDiff(breed) {
       // do work here
   }
}

// model constructor
constructor(id, name, breed, age, height, service){
    this.id = id;
    this.name = name,
    this.breed = breed,
    this.age = age,
    this.height = height,
    this.difHeight = BreedDiffService.GetBreedDiff(breed)
}

Please note that this isn't using an instance of the service but instead calling the method directly through the class. I also haven't tested this but this should probably work.