静态方法中的打字稿和角度访问服务实例

Question

I have a service which fetches the data object from the server. There is another class which is a general utility class. It has a static method in which i want to use service instance. but due to method being static this wont work. example code:

export class DataUtil {
    constructor(public core:CoreStructureService){

    }

    static fetchContact(id:string):ContactModel{
        for(let contact of this.core.contactList){
        if(contact.contactId == id)
            return contact
        }
    }

}

This will not compile as the line this.core.contactList in the for stmt is not valid. being method static i cannot refer core as this.core. So how do i fix this.

Answer 1

At the risk of the reputation I'm posting this as an answer.

Do NOT access core service methods from a static method. This is just bad. And this is exactly why the compiler is slapping you.

---

Have your fetchContact method an instance method instead of static.

export class DataUtil {
    constructor(public core:CoreStructureService){

    }

    fetchContact(id:string):ContactModel{
        for(let contact of this.core.contactList){
        if(contact.contactId == id)
            return contact
        }
    }

}

---

But... yes, you could work around it in a very dirty, half-working way. I am intentionally not going to describe it.

But, but, but... No, you're trying to do a bad thing.

Answer 2

If DataUtil was a service injected by Angular, it would not be destroyed until the corresponding injector is destroyed. I doubt you will have performance problems because of class instantiation. Try it with a regular service and only come back to this problem, if you really do have performance issues.

For further information, have a look at the Angular docs .