Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

TypeError: Cannot read property 'length' of undefined - when using .error()

See original GitHub issue

When trying to set a custom error message as per Joi API reference, for example: Joi.string().error(new Error('expected a string, actually')) then express-validation throws TypeError: Cannot read property 'length' of undefined in index.js line 76 because .error(new Error('message')) produces an Error instance without .details or other decorations of the ValidationError so errors.details.length cannot be accessed directly as errors.details is undefined.

Should another route be chosen to allow for custom error messages (especially important for regexes) or should the condition be improved to distinguish between ValidationErrors and generic Errors?

Issue Analytics

State:
Created 7 years ago
Comments:7 (1 by maintainers)

Top GitHub Comments

1reaction

colthreepvcommented, Mar 16, 2017

Sure, I see your point, probably will go with that (1), the custom branch should be a little more solid now.

I will see how that merges in the 2.x branch, will release it also for 1.x version to avoid application crashes

0reactions

AndrewKeigcommented, Mar 6, 2020

Closing, released 3.0

Top Results From Across the Web

Cannot read properties of undefined (reading 'length') - TrackJS

This message indicates that our code expects to have an object with a length property, but that object was not present. length is...

Typeerror: Cannot Read Property 'length' of Undefined

A typeerror length of undefined can indicate that the actual type of an operand is different from the expected type. This error can...

ERROR TypeError: Cannot read property 'length' of undefined

I got stuck in a similar situation where even after assigning results as an array ( as shown below ), the error persisted....

[SOLVED] Cannot Read Property 'length' of Undefined in JS

To fix the “cannot read property 'length' of undefined” error, perform an undefined check on the variable before accessing the length property ......

Cannot read properties of undefined (reading 'length') in JS

The "TypeError: Cannot read properties of undefined (reading 'length')" error occurs when accessing the length property on an undefined value. To solve the ......