Definitelytyped: @types/yup: How to strongly-type ObjectSchema

[mellis481]

I'm using yup with Formik in my React app which I've written in Typescript. I have the following FormikProps interface:

export interface InvoiceLevelTotal {
  amount?: number;
  currency?: string;
}

I've created the following ObjectSchema which I'm ultimately passing into the validationSchema property of my Formik:

const formSchema: Yup.ObjectSchema<InvoiceLevelTotal> = Yup.object().shape({
  amount: Yup.number().required('Amount is required'),
  currency: Yup.string().required('Currency is required')
});

As you can see, I'm attempting to type my ObjectSchema against my interface for type checking purposes, however if I change currency to currrrrrency, it does not throw a Typescript compile-time error like I would expect.

How can I strongly-type an ObjectSchema?

[mellis481]

It looks like the code should actually be as follows:

const formSchema = Yup.object<InvoiceLevelTotal>().shape({
  amount: Yup.number().required('Amount is required'),
  currency: Yup.string().required('Currency is required')
});

[esanzgar]

In [email protected], I was able able to enforce the type in this way:

const formSchema = Yup.object().shape<InvoiceLevelTotal>({
  amount: Yup.number().required('Amount is required'),
  currency: Yup.string().required('Currency is required')
});

However, is there any way to infer a type from the schema, so that there is no need of creating the type twice. Short of like this:

const formSchema = Yup.object().shape({
  amount: Yup.number().required('Amount is required'),
  currency: Yup.string().required('Currency is required')
});

type InvoiceLevelTotal = typeof formSchema.[something]

[jedrichards]

@esanzgar Yep, looks like it: https://github.com/jquense/yup#typescript-support

[esanzgar]

@jedrichards thanks, that exactly what I was looking for...

@esanzgar Yep, looks like it: https://github.com/jquense/yup#typescript-support