Javascript number representation

[marshallford]

Context

• node version: 8.6
• joi version: 13.0.2
• environment (node, browser): Node
• used with (hapi, standalone, ...): standalone
• any other relevant information:

What are you trying to achieve or the steps to reproduce ?

The primary reason that I am opening this issue is to start a discussion about number representation. See this issue from the node postgres lib for a good summary. Basically, if an integer schema is given to Joi will/should it be valid if it is a string type because it has to be a string? How does the convert option effect the outcome? Will Joi convert the string to a Javascript number type and cause lost precision?

Thanks!

const schema = {
  bigserial: Joi.number.integer(),
}

[WesTyler]

Will Joi convert the string to a Javascript number type

Yes. Joi.number().integer().validate('2'); // { error: null, value: 2

and cause lost precision

No, it's an integer. As long as your integer is smaller than Number.MAX_SAFE_INTEGER // 9007199254740991

You can prevent the convert option from allowing strings to be considered valid and converting to numbers though:

Joi.number().integer().validate('2', { convert: false }); // ValidationError: "value" must be a number

or

Joi.number().integer().options({convert: false}).validate('2'); // ValidationError: "value" must be a number

[marshallford]

Thanks for the clarification however my main concern still stands. Lets say I have an integer that is over 9007199254740991 represented as a string like the issue I linked recommends. Shouldn't Joi be able to handle this? Quite a few database datatypes allow numeric values over the Javascript max safe value.

[WesTyler]

Shouldn't Joi be able to handle this?

I honestly think no, since JS itself does not.

[Marsup]

I agree that it's unreasonable to accept numbers that we know could be wrong. I have no intention of embedding any high precision math libraries to deal with numbers as I consider it to be a pretty marginal use case, but you're free to make your own number extension doing that.

[marshallford]

I hear you in regards to Joi shouldn't handle something that Javascript itself doesn't handle, however I don't agree it is a marginal use case. From my view, Joi validates data, and for a lot of folks their data comes from outside the NodeJS/Javascript world. Data can come from other programming languages, from databases, legacy applications, etc. As a particular example, the primary keys of databases tend to rely on large numbers for uniqueness. In fact, Joi's intro mentions Facebook as a hypothetical use-case for Joi, surely they have the databases with high precision numbers?

At the end of day I understand wanting to keep the project scope focused, I'm just a little bummed. Thanks for all the work you do.

[Marsup]

I'm going to close this one in favor of #1531 which gives us a practical path forward, without having to use a new library for that. From a quick scan of npm, I didn't see any joi extension dealing with those numbers, I'm not sure if there's no interest for that or if people are just dealing with it in another way.