Support Array validation

[kettanaito]

What

Need to support Array validation.

1. Array as a value of object's property.
2. Root-level Array.

How

• Have a "mask" approach, where all Array members must satisfy a predicate.
• Have an index-based approach, where each Array member may have unique predicate.

[marcosvega91]

For arrays you can use this approach. What do you have in mind?

useSchema(
  {
    'users.name': (value, pointer) => value.length > 10,
  },
  {
    users: [
      name: 'Marco'
   ],
  },
)

[kettanaito]

That looks like a good start, @marcosvega91!

I was thinking that useSchema should be able to accept a root-level array as well. Something like:

useSchema([1, 2, 3], [1, 2, 3]) // OK!

The complexity comes with describing a spec of expected data.

// Validate each Array member against a predicate.
useSchema([1, 2, 3], (value) => !isNaN(value)) 

// Validate each Array member against a unique predicate.
useSchema(
  [1, 'admin', { firstName: 'John' }], 
  () => [
    (value) => !isNaN(value),
    (value) => value === 'admin',
    (value) => ({
    // Regular schema validation
      firstName: value => value === 'John'
    })
  ]
)

It gets more complex, when you wish to validate a portion of Array against a general predicate, and a portion against exact predicate functions.

I think we should approach this from the specification point of view, defining what features should be supported.

[marcosvega91]

Array of course should be implemented 💯
I'm thinking about the use of array with multiple predicate...mmmm.. Do you have a real example of this use?

[kettanaito]

Validating a tuple, for example:

type UserInfo = [string, number]

const user: UserInfo = ['John', 32]

useSchema(user, [validateUsername, validateAge])