Stimulus Inline Input Validations

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A Stimulus controller for validating form inputs and rendering their errors in a custom error element. Validations are performed on input and blur events.

Looking for another awesome validations library to try? Check out Formulus

Installation

StimulusJS installation is required.

Add the package to your project:

yarn add stimulus-inline-input-validations

Import and register InputValidator to your application

import {InputValidator} from "stimulus-inline-input-validations"
application.register("input-validator", InputValidator)

1. Add data-controller="input-validator" to your form or any parent element of <input> elements you want to validate.

<div data-controller="input-validator">
...
</div>

2. Add an <input> element with the data-input-validator-target="field" and data-field attribute that uniquely identifies the field.

<div data-controller="input-validator">
    <input 
      type="text" 
      data-input-validator-target="field" 
      data-field='fullName'
    >
    ...
</div>

3. Add an errors element with the data-input-validator-target="errors" attribute and a data-field name that matches the corrosponding input element. This is where any errors from the matching data-field will be rendered.

<div data-controller="input-validator">
    <input 
      type="text" 
      data-input-validator-target="field" 
      data-field='fullName'>

    <div
      data-input-validator-target="errors"
      data-field="fullName"
      class="">Errors will be rendered here</div>
</div>

4. Add, mix, and match validations attributes to the input field

<div data-controller="input-validator">
    <input 
      type="text" 
      data-input-validator-target="field" 
      data-field='fullName'
      data-validates-presence
      data-validates-length="5,10"
      data-validates-numericality
      data-validates-email
      >

    <div
      data-input-validator-target="errors"
      data-field="fullName"
      class=""></div>
</div>

Standard Validation attributes

Attribute	Description	Renders
data-validates-presence	Validates presence	<div error="presence">Can't be blank</div>
data-validates-length="5,10"	Validates length in format "min,max"	<div error="length-min">Too short. Must be 5 characters long</div>
data-validates-numericality	Ensures value is a Number	<div error="numericality">Must be a number</div>
data-validates-email	Ensures value is in Email format	<div error="email">Invalid email format</div>
data-validates-strong-password	Ensures value is strong password	<div error="strong-password-length">Must be at least 10 characters long</div>, <div error="strong-password-special-character">Must contain at least one special character (!@#$%^&*) </div>, <div error="strong-password-capital-letter">Must contain at least one capital letter (A-Z)</div>
data-validations="[{"presence": true}, {"email": true}, {"numericality": true}, {"length": {"min": 5, "max": 10}}]"	Handles multiple validations from a json-friendly-string	<div error="presence">...</div> <div error="length-min">...</div> <div error="numericality">...</div> <div error="email">...</div>

Multiple validations passed as a json-friendly string

You can also pass multiple validations as a json-friendly string with the data-validations attribute.

Example:

<input 
  type="text" 
  data-input-validator-target="field" 
  data-field='jsonBulkValidations'
  data-validations='[{"presence": true}, {"email": true}, {"numericality": true}, {"length": {"min": 5, "max": 10}}]'
>

Will render

<div data-input-validator-target="errors" data-field="jsonBulkValidations">
    <div error="presence">Can't be blank</div>
    <div error="length-min">Too short. Must be 5 characters long</div>
    <div error="numericality">Must be a number</div>
    <div error="email">Invalid email format</div>
</div>

Usage in Rails: Leveraging existing model validations in Rails form helpers

1. Add a json_validations_for method to application_helper.rb

module ApplicationHelper
  def json_validations_for(model, field)
    validations_hash = {}

    validators = model.class.validators_on(field)
    validators.each do |validator|
      validator_name = validator.class.name.demodulize.underscore.to_sym

      if validator_name == :length_validator
        options = validator.options.dup
        validations_hash[:length] = { min: options[:minimum].present? ? options[:minimum] : 1,
                                      max: options[:maximum].present? ? options[:maximum] : 1000 }
      end

      validations_hash[:presence] = true if validator_name == :presence_validator
      validations_hash[:numericality] = true if validator_name == :numericality_validator
    end

    validations_hash[:strong_password] = true if field == :password
    validations_hash[:email] = true if field == :email

    validations = validations_hash.map do |key, value|
      { key.to_s => value }
    end

    validations.to_json.html_safe
  end
end

2. Use the json_validations_for helper method in your Rails form helpers

<%= f.text_field :email,
                  data: {
                    input_validator_target:"field",
                    field: :email,
                    validations: json_validations_for(@user, :email)
                  } %>
<div data-input-validator-target="errors" data-field="email"></div>

Make sure you have a matching errors element with data-input-validator-target="errors" and matching data-field=""

i18n

You can use the data-input-validator-i18n-locale attribute to specify a locale for error messages.

<form data-controller="input-validator" data-input-validator-i18n-locale="es">
...
<form>

Supported languages values:

Value	Language
en	English
es	Spanish
fr	French
pt-BR	Portugese (Brazil)
zh-CN	Chinese (Simplified)
zh-TW	Chinese (Traditional)