add base API error messages

app/controllers/api/api_base_controller.rb

@@ -15,6 +15,10 @@ module Api
     before_action :authenticate_user!
     check_authorization
 
+    rescue_from Params::BaseValidator::InvalidParameterError do |e|
+      render json: { error: e.message }, status: :unprocessable_entity
+    end
+
     if Rails.env.production?
       rescue_from CanCan::AccessDenied do |e|
         Rollbar.error(e) if defined?(Rollbar)

app/controllers/api/submissions_controller.rb

@@ -63,6 +63,8 @@ module Api
     end
 
     def create
+      Params::SubmissionCreateValidator.call(params, dry_run: true)
+
       return render json: { error: 'Template not found' }, status: :unprocessable_entity if @template.nil?
 
       if @template.fields.blank?

lib/params/base_validator.rb

@@ -0,0 +1,103 @@
+# frozen_string_literal: true
+
+module Params
+  class BaseValidator
+    InvalidParameterError = Class.new(StandardError)
+
+    def self.call(...)
+      validator = new(...)
+
+      validator.call
+    rescue InvalidParameterError => e
+      Rollbar.error(e) if defined?(Rollbar)
+
+      raise e unless validator.dry_run?
+    rescue StandardError => e
+      Rollbar.error(e) if defined?(Rollbar)
+    end
+
+    attr_reader :params, :dry_run
+
+    alias dry_run? dry_run
+
+    def initialize(params, dry_run: false)
+      @params = params
+      @dry_run = dry_run
+      @current_path = ''
+    end
+
+    def call
+      raise NotImplementedError
+    end
+
+    def raise_error(message)
+      message += " in `#{@current_path}`." if @current_path.present?
+
+      raise InvalidParameterError, message unless dry_run?
+
+      Rollbar.error(message) if defined?(Rollbar)
+    end
+
+    def required(params, keys, message: nil)
+      keys = Array.wrap(keys)
+
+      return if keys.any? { |key| params&.dig(key).present? }
+
+      raise_error(message || "#{keys.join(' or ')} is required")
+    end
+
+    def type(params, key, type, message: nil)
+      return if params.blank?
+      return unless params.key?(key)
+
+      return if params[key].is_a?(type)
+
+      type = 'Object' if type == 'Hash'
+
+      raise_error(message || "#{key} must be a #{type}")
+    end
+
+    def in_path(params, path = [])
+      old_path = @current_path
+
+      @current_path = [old_path, *path].compact_blank.map(&:to_s).join('.')
+
+      param = params.dig(*path)
+
+      yield params.dig(*path) if param
+
+      @current_path = old_path
+    end
+
+    def in_path_each(params, path = [])
+      old_path = @current_path
+
+      params.dig(*path)&.each_with_index do |item, index|
+        @current_path = old_path + [*path].map(&:to_s).join('.') + "[#{index}]"
+
+        yield item if item
+      end
+
+      @current_path = old_path
+    end
+
+    def boolean(params, key, message: nil)
+      return if params.blank?
+      return unless params.key?(key)
+
+      value = ActiveModel::Type::Boolean.new.cast(params[key])
+
+      return if value.is_a?(TrueClass) || value.is_a?(FalseClass)
+
+      raise_error(message || "#{key} must be true or false")
+    end
+
+    def value_in(params, key, values, allow_nil: false, message: nil)
+      return if params.blank?
+      return if allow_nil && params[key].nil?
+      return if values.include?(params[key])
+
+      raise_error(message || "#{key} must be one of #{values.join(', ')}")
+    end
+  end
+end

lib/params/submission_create_validator.rb

@@ -0,0 +1,83 @@
+# frozen_string_literal: true
+
+module Params
+  class SubmissionCreateValidator < BaseValidator
+    # rubocop:disable Metrics
+    def call
+      if params[:submission].blank? && (params[:emails].present? || params[:email].present?)
+        validate_creation_from_emails(params)
+      else
+        validate_creation_from_submission(params)
+      end
+    end
+
+    def validate_creation_from_emails(params)
+      required(params, :template_id)
+      required(params, %i[emails email])
+
+      type(params, :emails, String)
+      boolean(params, :send_email)
+      type(params, :message, Hash)
+
+      in_path(params, :message) do |message_params|
+        type(message_params, :subject, String)
+        type(message_params, :body, String)
+
+        required(message_params, :body)
+      end
+
+      true
+    end
+
+    def validate_creation_from_submission(params)
+      required(params, :template_id)
+      required(params, %i[submission submissions])
+
+      in_path(params, :submission) do |submission_params|
+        required(submission_params, :submitters) if params[:submission]
+      end
+
+      boolean(params, :send_email)
+      boolean(params, :send_sms)
+      type(params, :order, String)
+      type(params, :completed_redirect_url, String)
+      type(params, :bcc_completed, String)
+      type(params, :message, Hash)
+
+      in_path(params, :message) do |message_params|
+        type(message_params, :subject, String)
+        type(message_params, :body, String)
+
+        required(message_params, :body)
+      end
+
+      value_in(params, :order, %w[preserved random], allow_nil: true)
+
+      in_path_each(params, %i[submission submitters]) do |submitter_params|
+        required(submitter_params, :email)
+
+        type(submitter_params, :name, String)
+        type(submitter_params, :email, String)
+        type(submitter_params, :phone, String)
+        type(submitter_params, :values, Hash)
+        boolean(submitter_params, :send_email)
+        boolean(submitter_params, :send_sms)
+        type(submitter_params, :completed_redirect_url, String)
+        type(submitter_params, :fields, Array)
+
+        in_path_each(submitter_params, %i[fields]) do |field_params|
+          required(field_params, :name)
+
+          type(field_params, :name, String)
+          type(field_params, :default_value, String)
+          type(field_params, :validation_pattern, String)
+          type(field_params, :invalid_message, String)
+          boolean(field_params, :readonly)
+        end
+      end
+
+      true
+    end
+    # rubocop:enable Metrics
+  end
+end