Joi: Throw custom Joi Errors

[eightyfive]

Hi,

That would be nice if Joi could throw custom Joi Errors:
https://github.com/hapijs/joi/blob/master/lib/errors.js#L140

Something in the fashion of:

/**
 * Custom Joi Error
 */
function JoiError() {
  Error.apply(this, arguments);

  this.details = [];
  // ...
}
JoiError.prototype = Object.create(Error.prototype);
JoiError.prototype.annotate = function () { /* ... */ }


// And later on...
try {
  // Some logic throwing a new JoiError(/* ... */);
  // ...
} catch (err if err instanceof JoiError) {
  // ...
  // Use Joi error details...
} catch (err if err instanceof TypeError) {
  // ...
}

It would make easier catching/narrowing to Joi-related errors in try {} catch (err) {} blocks as illustrated above. I am using koa and that would come very handy. For now I am testing if the thrown err has a details property which is not exactly future-proof nor elegant...

Or may you have a better suggestion to cast Joi errors only?

[eightyfive]

The conditional catch clauses syntax is not standard.

So my catch example would become:

try {
  // throw new JoiError(/* ... */);
} catch (err) {
  if (err instanceof JoiError) {
    // Use Joi error details...
  } else if (err instanceof TypeError) {
    // ... Etc.
  }
}

[Marsup]

What's the benefit from current

try {
  // throw new JoiError(/* ... */);
} catch (err) {
  if (err.name === 'ValidationError') {
    // Use Joi error details...
  } else if (err instanceof TypeError) {
    // ... Etc.
  }
}

?

[eightyfive]

It's cleaner and more future-proof (vendor specific, object casting)? But this is probably my Java/PHP OOP backgroung telling me that. (I cant help myself but thinking basing logic on string names isn't as strong as using a language strengths)

I missed the 'name' property, so my point isn't as much important anymore.

Thank you for replying!

[Marsup]

FWIW, instanceof performance sucks, like half as fast, that might be something you consider if you do it often.

[tejasmanohar]

:+1: for custom error objects. I don't like depending on code, name, etc. due to collision, especially with names as generic as ValidationError. Can we re-open this issue @Marsup @eightyfive?

[macalinao]

Mongoose also uses ValidationError as the name.

[Marsup]

Fair point, I'd go for a Joi.isError, fine for everyone ?

[AdriVanHoudt]

Why not isJoi like the isBoom?

[Marsup]

Closed by 52c1781.

[AdriVanHoudt]

:+1:

[maamun7]

if (error){
            if (error.name === 'ValidationError') {
                let customError = {};

                var spilitedErrorSmg = error.message.split(":");

                for (var key in spilitedErrorSmg) {
                    //Match 'Error' string with each line first 5 characters

                    if (spilitedErrorSmg[key].slice(0, 6).trim() == 'Error') {
                        let trimStr = spilitedErrorSmg[key].replace('Value', '').trim();
                        let spilitedWord = spilitedErrorSmg[key].replace('Value', '').trim().split(/`/)[1];
                        customError[spilitedWord] = trimStr;
                    }
                }
                res.json({msg: error._message, error: customError});
            }
        } else {
            res.json({msg: 'Successfully user registered'});
        }

Error Response:

{
    "msg": "User validation failed",
    "error": {
        "email": "Error, expected `email` to be unique.",
        "mobile": "Error, expected `mobile` to be unique."
    }
}

[uladkasach]

Out of curiosity, is there any reason _not_ to implement this error as an extension of the Error class? E.g.,

class JoiValidationError extends Error {
...
}

This seems like a more standard approach rather than assigning properties to an instance of the generic error class.

[lock[bot]]

This thread has been automatically locked due to inactivity. Please open a new issue for related bugs or questions following the new issue template instructions.