Leverage the optional attribute of an interface as a data type within openapi-typescript

Is there a way to use an interface property as a variable type in TypeScript?
I need to access the property: string type and use it as a variable type, but I'm having trouble accessing it.

interface foo {
  bar?: {
    baz: {
      property: string;
    };
  };
}

function f(input: foo['bar']['baz']['property']) {
  console.log(input);
}

I've tried looking into optional chaining rules for this issue, but none of the JavaScript chain methods seem to work here.

Error

Property 'baz' does not exist on type '{ baz: { property: string; } ' | undefined
typescripttypescript-typingsoptional-chaining

Answer №1

If you want to eliminate the | undefined portion from the foo['bar'] type, you can make use of the predefined NonNullable type. This will allow you to then access its attributes:

function exampleFunction(param: NonNullable<foo['bar']>['baz']['property']) {
  console.log(param);
}

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