Using api-check methods within custom checker

[tnrich]

Hey @kentcdodds,

I was hoping I could use api-check methods within a custom checker. Perhaps something sort of like this:

   randomData: function (val, name, location) {
        ac.throw([
            ac.shape({
                "name": ac.string,
                "site": ac.string,
                "forwardRegex": ac.string,
                "reverseRegex": ac.string,
                "cutType": ac.number,
                "dsForward": ac.number,
                "dsReverse": ac.number,
                "usForward": ac.number,
                "usReverse": ac.number
            })
        ], val);
    },

But I wasn't sure how to go about doing so exactly.. Is there a good way of doing this?

Thanks for all your time! It is much appreciated! Thomas

[tnrich]

I hope my question above was clear. I am basically trying to make a custom checker that leverages already existing types.

I'm thinking that maybe the best way to do this is to export the custom checker as a function attached to the api-check instance. For example:

var ac = require('api-check')({
    /* config options */
    output: {
        prefix: '',
        suffix: 'Good luck!',
        docsBaseUrl: 'no docs yet!'
    },
    verbose: false
}, { 
});

ac.customChecker1 = ac.shape({
        features: ac.array,
        specialNumber: ac.number,
        })

module.exports = ac;

It seems to me that this should work (so long as I don't override anything in the api-check name space by accident). Any thoughts?

Thanks! Thomas

[kentcdodds]

This should work fine. Another thing to try is that second parameter to the factory is an object of custom checkers which are added to your instance for you.

[kentcdodds]

I should also note that your first example actually calls ac.throw. You shouldn't actually throw errors in a checker, you simply return them.

Something like this should work:

return ac(ac.string, 32).message;

[kentcdodds]

Actually, sorry, you need to return an error object, so something more like this:

return new Error(ac(ac.string, 32).message);

However, that will contain a bit more api-check specific error info, so even better would be:

return ac.string(32);

So, as a full checker:

function myChecker(val, name, location, entireObjectIfInAShape) {
  // entireObjectIfInAShape only applies when the checker is being run in a `shape` like in the case of `shape.onlyIf` and `shape.requiredIf` etc.
  return ac.string(val, name, location, entireObjectIfInAShape); // or whatever else you want to do...
}