Response validation: Automatically coerce date data type to ISO string

[xeoneux]

Is your feature request related to a problem? Please describe.
When validating responses, if the data type is a js Date object, the validation of type string with format date-time fails.

{
  updatedAt: new Date() // fails
}

{
  updatedAt: "2010-13-30T23:12:35Z" // passes
}

Describe the solution you'd like
The lib should try to coerce the type to ISO string and then try validation on it.

{
  updatedAt: new Date() // should pass
}

Describe alternatives you've considered
I have to programmatically search through all the object to find a date data type and call the toISOString method on it to pass the output validation.

Additional context
None

[cdimascio]

@xeoneux is this occurring with response validation or request validation?

[xeoneux]

This is with response validation, didn't check the request part.

[cdimascio]

@xeoneux I did some investigation here. This is a bit tricky to solve. I'm not sure a satisfactory solution exists within Ajv.

I tried to create a custom Ajv keyword. A keyword will enable me to manipulate the Date object and convert it to a string e.g. toISOString(), The problem is described here and here note:

The only caveat at the moment is that custom keywords will be validated AFTER standard keywords in the same schema object, ...

AFTER is the issue. Ultimately, validation will fail despite modifying the data because an object is being passed to a schema that expects a string. Ajv executes custom keywords after other validation. This means that the type validation will occur before the new custom keyword has a chance to modify the data i.e change it from Date to iso string. This means thetype validation still occurs against the original Date object and thus fails since the data is still an object (Date), not a string. There is no current way to modify the data prior to validation. :/

I certainly agree that using new Date() in this context is convenient, but there does not seem to be an obvious solution other than you explicitly assigning e.g. updatedAt to a string e.g. new Date().toISOString(), rather than new Date(). Arguably, this is correct anyway, it was declared in the spec to expect a string 🤷‍♂️

The following is the keyword I was experimenting with. I added this keyword to the response validator.

    // if this keyword is set, convert a javascript Date to its iso string
    // TODO validate the date, use Date.parse
    ajv.addKeyword('x-eov-date-as-iso-string', {
      modifying: true,
      compile: function (sch, parentSchema) {
        const match = sch && parentSchema.format === 'date-time';
        return match
          ? function(value, objectKey, object, key) {
              object[key] = new Date(value).toISOString();
              return true;
            }
          : function() => return true;
      },
    });

[cdimascio]

keeping this open, perhaps folks have alternative ideas

[electrotype]

I have the same problem and found this, which is related: #246

Still a workaround, and I still don't know if it works, but hey.

[kapouer]

You can work around the addKeyword issue with https://github.com/pageboard/server/blob/876236cf0603e4a31b15d793605195008c350648/packages/api/index.js#L70-L100

[electrotype]

Do you accept bounties on issues? I could put 50$US for a fix on this one.

This is the only blocking issue for us. We have to JSON.parse(JSON.stringify(obj)) everything we send, simply for the date-time fields to pass the validation.

[cdimascio]

@pilerou has provided an option that will help solve this.
please have a look at #493 and provide feedback.
thanks!

[electrotype]

Feedback given. Thank you all for the effort on this issue.

[cdimascio]

this is solved in v4.10.0, please give it a try