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typescriptaurelia
Gena Verdel
Gena Verdel

Reputation: 636

Typescript interface fails to work

The following code fails with an error:

readCandidates is not a function:

Here is the code

export class Candidates {    
    private _dataService : ModelContracts.IDataService;    

    constructor(private tag: ModelContracts.ITag, private dataService: ModelContracts.IDataService) {
        this._value = tag;
        this._dataService = dataService;        
    }

    private _value : ModelContracts.ITag;
    public get value() : ModelContracts.ITag {
        return this._value;
    }
    public set value(v : ModelContracts.ITag) {
        this._value = v;
    }

    candidates = [];

    activate() {        
       this._dataService.readCandidates().then(candidates => this.candidates = candidates);
    }    
}

export interface IDataService {
    readCandidates(): Promise<ModelContracts.ICandidate[]>
} 

export class DataService {
    //some implementation
}

I'm using Aurelia bet 1.1.0 and Typescript. The dataService dependency gets injected but the function call fails.

Upvotes: 1

Views: 85

Answers (2)

Gena Verdel
Gena Verdel

Reputation: 636

it's impossible to use interfaces with DI in aurelia.

Upvotes: 0

Fenton
Fenton

Reputation: 250942

If the context of the call is not the class (for example, because you are calling activate as a callback or from an event) you'll need to make sure you sort out your scope.

For example:

activate = () => {        
   this._dataService.readCandidates().then(candidates => this.candidates = candidates);
}

Although there are some better ways to do this if you want to have a consitent approach to handling the responsibility of scope in TypeScript. The recommendation is to handle scope off-class, as the class shouldn't know how it is going to be called.

Upvotes: 1

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