Add constraints to table "federal_subjects"

app/models/federal_subject.rb

@@ -25,9 +25,15 @@ class FederalSubject < ApplicationRecord
   # Validations #
   ###############
 
-  validates :english_name, presence: true, uniqueness: true
+  validates :english_name,
+            presence: true,
+            uniqueness: true,
+            length: { in: 1..255 }
 
-  validates :native_name, presence: true, uniqueness: true
+  validates :native_name,
+            presence: true,
+            uniqueness: true,
+            length: { in: 1..255 }
 
   validates :number,
             presence: true,
@@ -36,6 +42,9 @@ class FederalSubject < ApplicationRecord
 
   validates :timezone, presence: true, format: { with: TIMEZONE_RE }
 
+  validate :english_name_looks_realistic
+  validate :native_name_looks_realistic
+
   ###########
   # Methods #
   ###########
@@ -47,4 +56,20 @@ class FederalSubject < ApplicationRecord
       english_name
     end
   end
+
+private
+
+  def english_name_looks_realistic
+    return if english_name.blank?
+
+    errors.add :english_name, :leading_spaces  if english_name.start_with? ' '
+    errors.add :english_name, :trailing_spaces if english_name.end_with?   ' '
+  end
+
+  def native_name_looks_realistic
+    return if native_name.blank?
+
+    errors.add :native_name, :leading_spaces  if native_name.start_with? ' '
+    errors.add :native_name, :trailing_spaces if native_name.end_with?   ' '
+  end
 end

config/locales/activerecord/en.yml

@@ -102,3 +102,5 @@ en:
         image_size: 'has too big size'
         image_format: 'has invalid format: %{content_type}'
         image_ext: 'has invalid extension: ".%{ext}"'
+        leading_spaces: 'has leading spaces'
+        trailing_spaces: 'has trailing spaces'

db/migrate/20190720124758_add_constraints_to_important_tables.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+class AddConstraintsToImportantTables < ActiveRecord::Migration[6.0]
+  def change
+    constraint :federal_subjects, :english_name, <<~SQL
+      length(english_name) BETWEEN 1 AND 255
+      AND
+      english_name !~ '^[[:space:]]{1,}'
+      AND
+      english_name !~ '[[:space:]]{1,}$'
+    SQL
+
+    constraint :federal_subjects, :native_name, <<~SQL
+      length(native_name) BETWEEN 1 AND 255
+      AND
+      native_name !~ '^[[:space:]]{1,}'
+      AND
+      native_name !~ '[[:space:]]{1,}$'
+    SQL
+
+    constraint :federal_subjects, :number, 'number > 0'
+  end
+
+private
+
+  def constraint(table, name, check)
+    reversible do |dir|
+      dir.up do
+        execute <<~SQL
+          ALTER TABLE #{table} ADD CONSTRAINT #{name} CHECK (#{check})
+        SQL
+      end
+
+      dir.down do
+        execute <<~SQL
+          ALTER TABLE #{table} DROP CONSTRAINT #{name}
+        SQL
+      end
+    end
+  end
+end

db/structure.sql

@@ -222,7 +222,10 @@ CREATE TABLE public.federal_subjects (
     english_name character varying NOT NULL,
     native_name character varying NOT NULL,
     number integer NOT NULL,
-    timezone interval NOT NULL
+    timezone interval NOT NULL,
+    CONSTRAINT english_name CHECK ((((length((english_name)::text) >= 1) AND (length((english_name)::text) <= 255)) AND ((english_name)::text !~ '^[[:space:]]{1,}'::text) AND ((english_name)::text !~ '[[:space:]]{1,}$'::text))),
+    CONSTRAINT native_name CHECK ((((length((native_name)::text) >= 1) AND (length((native_name)::text) <= 255)) AND ((native_name)::text !~ '^[[:space:]]{1,}'::text) AND ((native_name)::text !~ '[[:space:]]{1,}$'::text))),
+    CONSTRAINT number CHECK ((number > 0))
 );
 
 
@@ -1124,6 +1127,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20190718184543'),
 ('20190719224405'),
 ('20190720022446'),
-('20190720042127');
+('20190720042127'),
+('20190720124758');
 
 

spec/models/federal_subject_spec.rb

@@ -16,13 +16,37 @@ RSpec.describe FederalSubject do
   end
 
   describe '#english_name' do
+    def allow_value(*)
+      super.for :english_name
+    end
+
     it { is_expected.to validate_presence_of :english_name }
     it { is_expected.to validate_uniqueness_of :english_name }
+
+    it do
+      is_expected.to \
+        validate_length_of(:english_name).is_at_least(1).is_at_most(255)
+    end
+
+    it { is_expected.not_to allow_value ' Foo' }
+    it { is_expected.not_to allow_value 'Foo ' }
   end
 
   describe '#native_name' do
+    def allow_value(*)
+      super.for :native_name
+    end
+
     it { is_expected.to validate_presence_of :native_name }
     it { is_expected.to validate_uniqueness_of :native_name }
+
+    it do
+      is_expected.to \
+        validate_length_of(:native_name).is_at_least(1).is_at_most(255)
+    end
+
+    it { is_expected.not_to allow_value ' Foo' }
+    it { is_expected.not_to allow_value 'Foo ' }
   end
 
   describe '#number' do