I'd like to define an interface that allows you to supply content OR content_object but not both. You have to define one or the other. What is the simplest way to achieve this in TypeScript? I know I could say that content is string | object, but the rest of my code benefits if I can define it as described instead.

interface IModal {
    content?: string;
    content_object?: object;
}

I'd like to define an interface that allows you to supply content OR content_object but not both. You have to define one or the other. What is the simplest way to achieve this in TypeScript? I know I could say that content is string | object, but the rest of my code benefits if I can define it as described instead.

interface IModal {
    content?: string;
    content_object?: object;
}

• javascript
• typescript
• typescript-typings

• Are you just wanting to know how to implement the constraints? – Robert Harvey Commented May 10, 2018 at 22:10
• Yes. What I currently have says that both are optional, but both could be present as well. I want it to only allow 1, and ensure that exactly one are set. – jas7457 Commented May 10, 2018 at 22:11
• You'll need some validation in your implementation class. AFAIK you can't enforce such constraints in the interface itself. – Robert Harvey Commented May 10, 2018 at 22:13
• You could also try this: npmjs./package/typedcontract – Robert Harvey Commented May 10, 2018 at 22:15
• Hmmm interesting package, but a bit overkill for this one scenario. Thanks though. – jas7457 Commented May 10, 2018 at 22:18

1 Answer 1

type IModal = { content: string; content_object?: undefined } |
              { content_object: object; content?: undefined }

This answer contains only code and is therefore bad according to automated systems.