# How to skip blanks in nested array?

**URL:** <https://discourse.dry-rb.org/t/how-to-skip-blanks-in-nested-array/177>\
**Category:** dry-validation\
**Created:** [December 16, 2016, 4:17am UTC](https://discourse.dry-rb.org/t/how-to-skip-blanks-in-nested-array/177 "2016-12-16T04:17:05Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![francois](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.dry-rb.org/francois/32/73_2.png) [@francois](https://discourse.dry-rb.org/u/francois)\
**Post date:** [December 16, 2016, 4:17am UTC](https://discourse.dry-rb.org/t/how-to-skip-blanks-in-nested-array/177/1 "2016-12-16T04:17:05Z")

</div>

Hi all!

I have a followup question to [How to validate an array property itself and each item of array?](https://discuss.dry-rb.org/t/how-to-validate-an-array-property-itself-and-each-item-of-array/124). The UI I’m showing is a registration form, where one can type the names of all family members. Some families have more people than others, and I provide more fields than necessary. For example, I show 5 fields for children, when I know most families won’t have 5 children. Same with adults, where I provide 2 fields, but some families will only have one person.

The registration form requires at least one adult, but the family is allowed to have no children.

What I’d **like** to happen is when the form is submitted, blanks should be skipped: `["", " ", "\t", " "]` should evaluate to `[]`. This is my ideal case.

My form definition is as follows.

```ruby
NewFamilyForm = Dry::Validation.Form do
  required(:email).filled(format?: /.@.+[.][a-z]{1}/i)
  required(:name).filled(min_size?: 1)

  required(:adult).filled(:array?, min_size?: 1).each do
    none? | (str? & min_size?(1))
  end

  required(:child).each do
    none? | (str? & min_size?(1))
  end
end

```

When I call the form with no adults, I do not receive an error on the adult field, since the empty string is accepted. Here’s a failing test for me:

```ruby
def test_requires_at_least_one_adult
  result = NewFamilyForm.call("adult" => [""])
  assert_equal ["must be filled"], result.errors[:adult], result.errors.inspect
  assert_equal({adult: []}, result.output)
end

```

and running it:

```auto
  3) Failure:
NewFamilyFormTest#test_requires_at_least_one_adult [test/test_new_family_form.rb:19]:
{:email=>["is missing"], :name=>["is missing"], :child=>["is missing"]}.
Expected: ["must be filled"]
  Actual: nil

```

Is it possible to ignore blank values during validation? Ideally, `#output` would not return blank strings, but I can live with those. Should I pre-process the form before attempting form validation?

Thanks!  
François

---

<div class="post-metadata">

**Author:** ![solnic](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.dry-rb.org/solnic/32/779_2.png) [@solnic](https://discourse.dry-rb.org/u/solnic)\
**Post date:** [December 20, 2016, 11:47am UTC](https://discourse.dry-rb.org/t/how-to-skip-blanks-in-nested-array/177/2 "2016-12-20T11:47:38Z")

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Looks like you want to switch to explicit type specs and define a type that will pre-process the input:

```ruby
require 'dry-validation'

module Types
  include Dry::Types.module
end

FamilyNames = Types::Array.constructor { |a| a.reject(&:empty?) }

NewFamilyForm = Dry::Validation.Form do
  configure do
    config.type_specs = true
  end

  required(:email, :string).filled(format?: /.@.+[.][a-z]{1}/i)
  required(:name, :string).filled(min_size?: 1)

  required(:adult, FamilyNames).value(:array?, min_size?: 1) { each(:str?, min_size?: 1) }

  required(:child, FamilyNames).each(:str?, min_size?: 1)
end

puts NewFamilyForm.(adult: ['jane', '', 'john']).inspect

```

Explicit type specs will be very likely the default behavior in 1.0.0 so feel free to use it. We will probably keep type-inference as an optional plugin but with less support from the core team.

---

<div class="post-metadata">

**Author:** ![francois](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.dry-rb.org/francois/32/73_2.png) [@francois](https://discourse.dry-rb.org/u/francois)\
**Post date:** [December 20, 2016, 3:12pm UTC](https://discourse.dry-rb.org/t/how-to-skip-blanks-in-nested-array/177/3 "2016-12-20T15:12:19Z")

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Thank you @solnic. I see where explicit types are documented, but I failed to see the road from explicit types to being able to add my own types with a pre-processing step.

Would you like me to extend the example in [https://github.com/dry-rb/dry-rb.org/blob/master/source/gems/dry-validation/type-specs.html.md](https://github.com/dry-rb/dry-rb.org/blob/master/source/gems/dry-validation/type-specs.html.md) ? I’d be happy to write and submit a PR explaining a pre-processing step. I also believe a link from [https://github.com/dry-rb/dry-rb.org/blob/master/source/gems/dry-validation/array-as-input.html.md](https://github.com/dry-rb/dry-rb.org/blob/master/source/gems/dry-validation/array-as-input.html.md) to type-specs would be good. I looked long and hard at the array as input page.

---

<div class="post-metadata">

**Author:** ![solnic](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.dry-rb.org/solnic/32/779_2.png) [@solnic](https://discourse.dry-rb.org/u/solnic)\
**Post date:** [December 22, 2016, 10:00am UTC](https://discourse.dry-rb.org/t/how-to-skip-blanks-in-nested-array/177/4 "2016-12-22T10:00:40Z")

</div>

> [@francois](#):
>
> Would you like me to extend the example in [https://github.com/dry-rb/dry-rb.org/blob/master/source/gems/dry-validation/type-specs.html.md](https://github.com/dry-rb/dry-rb.org/blob/master/source/gems/dry-validation/type-specs.html.md) ? I’d be happy to write and submit a PR explaining a pre-processing step

That would be very helpful 🙂

---

<div class="post-metadata">

**Author:** ![francois](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.dry-rb.org/francois/32/73_2.png) [@francois](https://discourse.dry-rb.org/u/francois)\
**Post date:** [December 22, 2016, 10:18pm UTC](https://discourse.dry-rb.org/t/how-to-skip-blanks-in-nested-array/177/5 "2016-12-22T22:18:01Z")

</div>

I have created a PR, as promised: [Explain how to do input preprocessing (#129)](https://github.com/dry-rb/dry-rb.org/pull/129). Enjoy!