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Comment by 9034725985 | Hacker News Reader

yes, input is a json of some kind.

You could say technically could be simply { "Unsubscribe__c": false } or even {} both of which are silly in my case because there is no key for me to identify who the person is but they are valid inputs.

Or the test case I have is https://github.com/kusl/salesforcecontactmapper/blob/eff0b3e...

Or the input could have a thousand key values and I only care about some of them. What should my object look like? How do I create a class that says everything that ends in "__c" is something I care about? I tried unknown. I tried Object. How do I fix this (and learn something so I fix all future code I write)?

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You can go incredibly far with the type system.

If you wanna go down that rabbit hole, I'd suggest Typescript type challenges. Completely blew my mind when I came across it the first time.

When you start out with typescript you might think Omit<> and Partial<> are cool but holy hell, you can do so much more.

    input: Record<string, unknown>

Thank you. That gives me a red underline under ContactId and Email now. I think because input.Contact__c and input.ContactEmail__c are unknown. I think this is the right direction. What is my next step?

    const myOutput: Output = {
        ContactId: input.Contact__c,
        Email: input.ContactEmail__c,
        IsInternalUpdate: true,
        Preferences: mypreferences
    }

(property) Output.ContactId: string Type 'unknown' is not assignable to type 'string'.ts(2322) Output.ts(4, 5): The expected type comes from property 'ContactId' which is declared here on type 'Output'

What's wrong with Object?

If I set input as Object,

    if (input[prefCode] !== null) {
        currentValue = input[prefCode].toString();
    }

in the lines above, I see a red underline under input[prefCode]

> Element implicitly has an 'any' type because expression of type 'string' can't be used to index type 'Object'. No index signature with a parameter of type 'string' was found on type 'Object'.ts(7053)

Could you use a helper like

    function getProperty<T, K extends keyof T>(o: T, propertyName: K): T[K] {
        return o[propertyName];
    }

?

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