Make Nested deserialize throw ValidationError instead ValueError

[YuriHeupa]

Raising a ValueError doesn't make sense within deserialize context. Bad input data should be caught as a validation error, so it was changed to the proper error.

This also fixes a minor typo in the error message.

[sloria]

In this case, I think a ValueError is appropriate because it is raised when an invalid argument is passed to Related (rather than an invalid input to the schema).

Good catch on the typo though; I've fixed it on dev.

[YuriHeupa]

Think about the case were a model has a composite primary key, and a scalar integer is passed through the input field instead a nested object containing the columns values - The expected behavior is that this wrong input will throw a ValidationError, but in this case it'll throw a ValueError, which doesn't make sense. So the error will be raised for a invalid input to the schema.

[YuriHeupa]

@sloria It might be sense to be a ValueError, but it'll require a change in this check to cover the case that the input data doesn't match the expected structure. If it makes sense, then I'll make the proper changes.

[sloria]

Yes, it would be great if we could handle the cases of invalid input vs. invalid Schema specifically.

[YuriHeupa]

@sloria I've checked the use cases of this over and over again and I got to the conclusion that the ValueError would only be raised in case of an invalid input, if you find another one, please leave an example. The current ValueError message expressively states that it expects an input format that has not been given.

That said, I still believe it makes more sense to be a ValidationError, I just changed the code to call a fail() instead of using ValidationError directly.

[sloria]

@YuriHeupa OK, thanks for looking further into this. I think the behavior you've implemented is correct. 👍