From f6e8f18d89c7ad1aac3429941b5f71ab25b5e6c3 Mon Sep 17 00:00:00 2001
From: Kristina Lim <kristinalim.ph@gmail.com>
Date: Fri, 21 Sep 2018 12:16:06 +0800
Subject: [PATCH] Add validator for integer arrays

Example usage:

    validates :related_post_ids, integer_array: true
---
 app/validators/integer_array_validator.rb     | 63 +++++++++++++++++++
 config/locales/en.yml                         |  3 +
 .../integer_array_validator_spec.rb           | 57 +++++++++++++++++
 3 files changed, 123 insertions(+)
 create mode 100644 app/validators/integer_array_validator.rb
 create mode 100644 spec/validators/integer_array_validator_spec.rb

diff --git a/app/validators/integer_array_validator.rb b/app/validators/integer_array_validator.rb
new file mode 100644
index 0000000000..27042c972b
--- /dev/null
+++ b/app/validators/integer_array_validator.rb
@@ -0,0 +1,63 @@
+# Validates an integer array
+#
+# This uses Integer() behind the scenes.
+#
+# === Example
+#
+#   class Post
+#     include ActiveModel::Validations
+#
+#     attr_accessor :related_post_ids
+#     validates :related_post_ids, integer_array: true
+#   end
+#
+#   post = Post.new
+#
+#   post.related_post_ids = nil
+#   post.valid?                     # => true
+#
+#   post.related_post_ids = []
+#   post.valid?                     # => true
+#
+#   post.related_post_ids = 1
+#   post.valid?                     # => false
+#   post.errors[:related_post_ids]  # => ["must be an array"]
+#
+#   post.related_post_ids = [1, 2, 3]
+#   post.valid?                     # => true
+#
+#   post.related_post_ids = ["1", "2", "3"]
+#   post.valid?                     # => true
+#
+#   post.related_post_ids = [1, "2", "Not Integer", 3]
+#   post.valid?                     # => false
+#   post.errors[:related_post_ids]  # => ["must contain only valid integers"]
+class IntegerArrayValidator < ActiveModel::EachValidator
+  NOT_ARRAY_ERROR = I18n.t("validators.integer_array_validator.not_array_error")
+  INVALID_ELEMENT_ERROR = I18n.t("validators.integer_array_validator.invalid_element_error")
+
+  def validate_each(record, attribute, value)
+    return if value.nil?
+
+    validate_attribute_is_array(record, attribute, value)
+    validate_attribute_elements_are_integer(record, attribute, value)
+  end
+
+  protected
+
+  def validate_attribute_is_array(record, attribute, value)
+    return if value.is_a?(Array)
+
+    record.errors.add(attribute, NOT_ARRAY_ERROR)
+  end
+
+  def validate_attribute_elements_are_integer(record, attribute, array)
+    return unless array.is_a?(Array)
+
+    array.each do |element|
+      Integer(element)
+    end
+  rescue ArgumentError
+    record.errors.add(attribute, INVALID_ELEMENT_ERROR)
+  end
+end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index cea3d34d6b..f59b6d4bba 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -104,6 +104,9 @@ en:
     date_time_string_validator:
       not_string_error: "must be a string"
       invalid_format_error: "must be valid"
+    integer_array_validator:
+      not_array_error: "must be an array"
+      invalid_element_error: "must contain only valid integers"
 
   enterprise_mailer:
     confirmation_instructions:
diff --git a/spec/validators/integer_array_validator_spec.rb b/spec/validators/integer_array_validator_spec.rb
new file mode 100644
index 0000000000..156409f0d0
--- /dev/null
+++ b/spec/validators/integer_array_validator_spec.rb
@@ -0,0 +1,57 @@
+require "spec_helper"
+
+describe IntegerArrayValidator do
+  class TestModel
+    include ActiveModel::Validations
+
+    attr_accessor :ids
+
+    validates :ids, integer_array: true
+  end
+
+  describe "internationalization" do
+    it "has translation for NOT_ARRAY_ERROR" do
+      expect(described_class::NOT_ARRAY_ERROR).not_to be_blank
+    end
+
+    it "has translation for INVALID_ELEMENT_ERROR" do
+      expect(described_class::INVALID_ELEMENT_ERROR).not_to be_blank
+    end
+  end
+
+  describe "validation" do
+    let(:instance) { TestModel.new }
+
+    it "does not add error when nil" do
+      instance.ids = nil
+      expect(instance).to be_valid
+    end
+
+    it "does not add error when blank array" do
+      instance.ids = []
+      expect(instance).to be_valid
+    end
+
+    it "adds error NOT_ARRAY_ERROR when neither nil nor an array" do
+      instance.ids = 1
+      expect(instance).not_to be_valid
+      expect(instance.errors[:ids]).to include(described_class::NOT_ARRAY_ERROR)
+    end
+
+    it "does not add error when array of integers" do
+      instance.ids = [1, 2, 3]
+      expect(instance).to be_valid
+    end
+
+    it "does not add error when array of integers as String" do
+      instance.ids = ["1", "2", "3"]
+      expect(instance).to be_valid
+    end
+
+    it "adds error INVALID_ELEMENT_ERROR when an element cannot be parsed as Integer" do
+      instance.ids = [1, "2", "Not Integer", 3]
+      expect(instance).not_to be_valid
+      expect(instance.errors[:ids]).to include(described_class::INVALID_ELEMENT_ERROR)
+    end
+  end
+end