CODEWITHSUNDEEP
javascriptbackbone.jstypescript
user888734
user888734

Reputation: 3897

Define a collection's model type in Backbone using Typescript

I'm trying to use Backbone with Typescript, and I'm not following Typescript's syntax for how to define which type of model a collection will hold.

module Application.Collections {
    export class Library extends Backbone.Collection {
        model = Application.Models.Book; // THIS LINE DOESN'T WORK
        constructor(options?) {
            super(options);
        };
    }
}

module Application.Models {
    export class Bookextends Backbone.Model {
        constructor(options?) {
            super(options);
        }
    }
}

The error I get is:

Type of overridden member 'model' is not subtype of original
member defined by type 'Collection';

It's also not clear to me when I should put definitions like this in the constructor, or whether it matters. I tried:

constructor(options?) {
        super(options);
        this.model = Application.Models.Entity;
};

Which says:

Cannot convert 'new(options?:any) => Models.Template' to 'Backbone.Model'

What I'm really trying to do is define a model type that has a few utility methods - when the basic model data is fetched from the server, I want the model to initialize and calculate a few convenience properties based on the server data. But this isn't happening, because the collection.fetch() doesn't think the return model is of any specific type.

Upvotes: 2

Views: 1385

Answers (2)

annymsMthd
annymsMthd

Reputation: 94

Declare the model before "super(options);"

    module Application.Models {
         export class Book extends Backbone.Model {
         constructor(options?) {
             super(options);
         }
    }    

    module Application.Collections {
        export class Library extends Backbone.Collection {

            constructor(options?) {
                this.model = Application.Models.Book;
                super(options);
            };
        }
    }

Upvotes: 2

Fenton
Fenton

Reputation: 251072

If you want to type that variable, you would use:

model: Application.Models.Book;

If you want the class name at runtime, you can either use a string, or this method of obtaining the class name at runtime.

model = 'Application.Models.Book';

Or

model = Describer.getName(someObject);

There is a limit on this second method that you only get the class name, not the full path.

Upvotes: 1

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