Finding out the nature of nullable attributes within an object: How can it be done?

Question

Finding out the nature of nullable attributes within an object: How can it be done?

I'm facing an issue with saving incomplete forms where I have a form being filled out by a user and I wish to allow the form to be saved even if it's not fully complete.

Before sending the object to my API, I need to set any null attributes to either 0 or an empty string depending on whether the attribute is supposed to be a number or a string. If this isn't done, the API won't accept the object.

The current approach I am trying involves:

    for (const property in this._object) {
        if (this._object[property] == null) {
            //need assistance in determining if [property] should be treated as a string or a number
        }
    }

Since typeof check doesn't work on null values, I am unable to distinguish between strings and numbers when properties are null. Is there a way to figure out the type of an object that is currently null? All properties are strongly typed in the object class so TypeScript knows their types at compile time.

javascript typescript

Answer 1

Answer №1

Attempting to accomplish this task is impossible because TypeScript types are only present during compilation. Once the code starts running, those types will no longer be available.

To come close to achieving your goal, you could consider adding runtime type information to your data when it gets saved from the form. For example, you could include something like

{ "__type": "string", "value: null }

, or have the form save the data directly into memory in the required format.

Answer 2

Attempting to accomplish this task is impossible because TypeScript types are only present during compilation. Once the code starts running, those types will no longer be available.

To come close to achieving your goal, you could consider adding runtime type information to your data when it gets saved from the form. For example, you could include something like

{ "__type": "string", "value: null }

, or have the form save the data directly into memory in the required format.

Finding out the nature of nullable attributes within an object: How can it be done?

Answer №1

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