Errors for 'required' validation should include missing property about ajv

[stefk]

Thanks :)

[epoberezkin]

you're welcome. Thanks for the motivation to improve it :)

[epoberezkin]

On it.

[epoberezkin]

It is a design choice for performance rather than shortcoming :) Required keyword is validated in a single expression (conditions for each property are connected with &&), not in the loop, so ajv has no knowledge of which specific property is missing.

Having said that I agree that one wants to know what exactly is missing, not just that something is missing :)

I'll see how I can improve it without damaging performance. Maybe it should be an option. Or I have another idea...

Thank you for pointing it out.

[stefk]

Hi,

I understand performance is an important consideration, but precise error reporting is also really valuable.

I'm currently building a format specification using JSONSchema, and as the multiple schemas involved are subject to many changes at this point, I've set up a test suite automating validation of valid/invalid data samples and generating a primitive documentation above it.

The current error reporting of ajv forces me to make assertions on error messages, which aren't always precise, and the whole approach of relying on message strings is quite fragile. I'd really like to have something like error codes/constants along with better data paths and messages.

@cdmcnamara's proposal:

{ 
  keyword: 'required',
  dataPath: '.amount.value',
  message: 'property value is required' 
}

would allow cleaner assertions on errors like:

keyword === 'required' 
dataPath === '.amount.value

[epoberezkin]

I agree. I have a solution in mind - it will have missing properties in dataPath without affecting performance. If you use allErrors=true then each missing property will create an error (not one error as it is now). If allErrors is not passed it will return the error with the name of the first missing property. Just need a little time for that.

And thanks for using it :)

[cdm6a]

Thanks for the quick reply! This solution sounds ideal.

[epoberezkin]

done in 0.6.1

[epoberezkin]

By the way, the error message for "required" was simply listing all required properties, not just missing ones. So making assertions on it wasn't the right thing to do.