Simplify limits to text columns on new tables

Changes the rubocop to complain about usage for new
migrations.

db/migrate/20201029144444_create_vulnerability_finding_links.rb

@@ -11,8 +11,8 @@ class CreateVulnerabilityFindingLinks < ActiveRecord::Migration[6.0]
     create_table :vulnerability_finding_links, if_not_exists: true do |t|
       t.timestamps_with_timezone null: false
       t.references :vulnerability_occurrence, index: { name: 'finding_links_on_vulnerability_occurrence_id' }, null: false, foreign_key: { on_delete: :cascade }
-      t.text :name, limit: 255
-      t.text :url, limit: 2048, null: false
+      t.text :name, limit: 255 # rubocop:disable Migration/AddLimitToTextColumns
+      t.text :url, limit: 2048, null: false # rubocop:disable Migration/AddLimitToTextColumns
     end
 
     add_text_limit :vulnerability_finding_links, :name, 255

doc/development/database/strings_and_the_text_data_type.md

@@ -12,7 +12,7 @@ When adding new columns that will be used to store strings or other textual info
 
 1. We always use the `text` data type instead of the `string` data type.
 1. `text` columns should always have a limit set, either by using the `create_table` with
-the `#text_limit` helper (see below) when creating a table, or by using the `add_text_limit`
+the `#text ... limit: 100` helper (see below) when creating a table, or by using the `add_text_limit`
 when altering an existing table.
 
 The standard Rails `text` column type can not be defined with a limit, but we extend `create_table` to
@@ -43,8 +43,8 @@ Don't use text columns for `attr_encrypted` attributes. Use a
 ## Create a new table with text columns
 
 When adding a new table, the limits for all text columns should be added in the same migration as
-the table creation. We add a `#text_limit` method to Rails' `create_table`, which allows adding limits
-for text columns.
+the table creation. We add a `limit:` attribute to Rails' `#text` method, which allows adding a limit
+for this column.
 
 For example, consider a migration that creates a table with two text columns,
 `db/migrate/20200401000001_create_db_guides.rb`:
@@ -54,11 +54,8 @@ class CreateDbGuides < Gitlab::Database::Migration[1.0]
   def change
     create_table :db_guides do |t|
       t.bigint :stars, default: 0, null: false
-      t.text :title
-      t.text :notes
-
-      t.text_limit :title, 128
-      t.text_limit :notes, 1024
+      t.text :title, limit: 128
+      t.text :notes, limit: 1024
     end
   end
 end

lib/gitlab/database/migration_helpers/v2.rb

@@ -30,16 +30,21 @@ module Gitlab
           helper_context = self
 
           super do |t|
-            t.define_singleton_method(:text_limit) do |column_name, limit, name: nil|
-              # rubocop:disable GitlabSecurity/PublicSend
-              name = helper_context.send(:text_limit_name, table_name, column_name, name: name)
-              helper_context.send(:validate_check_constraint_name!, name)
-              # rubocop:enable GitlabSecurity/PublicSend
+            t.define_singleton_method(:text) do |column_name, **kwargs|
+              limit = kwargs.delete(:limit)
 
-              column_name = helper_context.quote_column_name(column_name)
-              definition = "char_length(#{column_name}) <= #{limit}"
+              super(column_name, **kwargs)
 
-              t.check_constraint(definition, name: name)
+              if limit
+                # rubocop:disable GitlabSecurity/PublicSend
+                name = helper_context.send(:text_limit_name, table_name, column_name)
+                # rubocop:enable GitlabSecurity/PublicSend
+
+                column_name = helper_context.quote_column_name(column_name)
+                definition = "char_length(#{column_name}) <= #{limit}"
+
+                t.check_constraint(definition, name: name)
+              end
             end
 
             t.instance_eval(&block) unless block.nil?

rubocop/cop/migration/add_limit_to_text_columns.rb

@@ -13,8 +13,13 @@ module RuboCop
       class AddLimitToTextColumns < RuboCop::Cop::Cop
         include MigrationHelpers
 
+        TEXT_LIMIT_ATTRIBUTE_ALLOWED_SINCE = 2021_09_10_00_00_00
+
         MSG = 'Text columns should always have a limit set (255 is suggested). ' \
-          'You can add a limit to a `text` column by using `add_text_limit`'
+          'You can add a limit to a `text` column by using `add_text_limit` or by using `.text... limit: 255` inside `create_table`'
+
+        TEXT_LIMIT_ATTRIBUTE_NOT_ALLOWED = 'Text columns should always have a limit set (255 is suggested). Using limit: is not supported in this version. ' \
+        'You can add a limit to a `text` column by using `add_text_limit` or `.text_limit` inside `create_table`'
 
         def_node_matcher :reverting?, <<~PATTERN
           (def :down ...)
@@ -37,15 +42,29 @@ module RuboCop
           node.each_descendant(:send) do |send_node|
             next unless text_operation?(send_node)
 
-            # We require a limit for the same table and attribute name
-            if text_limit_missing?(node, *table_and_attribute_name(send_node))
-              add_offense(send_node, location: :selector)
+            if text_operation_with_limit?(send_node)
+              add_offense(send_node, location: :selector, message: TEXT_LIMIT_ATTRIBUTE_NOT_ALLOWED) if version(node) < TEXT_LIMIT_ATTRIBUTE_ALLOWED_SINCE
+            else
+              # We require a limit for the same table and attribute name
+              if text_limit_missing?(node, *table_and_attribute_name(send_node))
+                add_offense(send_node, location: :selector)
+              end
             end
           end
         end
 
         private
 
+        def text_operation_with_limit?(node)
+          migration_method = node.children[1]
+
+          return unless migration_method == :text
+
+          if attributes = node.children[3]
+            attributes.pairs.find { |pair| pair.key.value == :limit }.present?
+          end
+        end
+
         def text_operation?(node)
           # Don't complain about text arrays
           return false if array_column?(node)

spec/lib/gitlab/database/migration_helpers/v2_spec.rb

@@ -235,78 +235,17 @@ RSpec.describe Gitlab::Database::MigrationHelpers::V2 do
       ]
     end
 
-    context 'when no check constraints are defined' do
+    context 'using a limit: attribute on .text' do
       it 'creates the table as expected' do
         migration.create_table table_name do |t|
           t.timestamps_with_timezone
           t.integer :some_id, null: false
           t.boolean :active, null: false, default: true
-          t.text :name
+          t.text :name, limit: 100
         end
 
         expect_table_columns_to_match(column_attributes, table_name)
-      end
-    end
-
-    context 'when a text_limit defined' do
-      context 'when the text_limit is explicity named' do
-        it 'creates the table as expected' do
-          migration.create_table table_name do |t|
-            t.timestamps_with_timezone
-            t.integer :some_id, null: false
-            t.boolean :active, null: false, default: true
-            t.text :name
-
-            t.text_limit :name, 255, name: 'check_name_length'
-            t.check_constraint 'some_id > 0', name: 'some_id_is_positive'
-          end
-
-          expect_table_columns_to_match(column_attributes, table_name)
-
-          expect_check_constraint(table_name, 'check_name_length', 'char_length(name) <= 255')
-          expect_check_constraint(table_name, 'some_id_is_positive', 'some_id > 0')
-        end
-      end
-
-      context 'when the text_limit is not named' do
-        it 'creates the table as expected, naming the text limit' do
-          migration.create_table table_name do |t|
-            t.timestamps_with_timezone
-            t.integer :some_id, null: false
-            t.boolean :active, null: false, default: true
-            t.text :name
-
-            t.text_limit :name, 255
-            t.check_constraint 'some_id > 0', name: 'some_id_is_positive'
-          end
-
-          expect_table_columns_to_match(column_attributes, table_name)
-
-          expect_check_constraint(table_name, 'check_cda6f69506', 'char_length(name) <= 255')
-          expect_check_constraint(table_name, 'some_id_is_positive', 'some_id > 0')
-        end
-      end
-
-      context 'when text_limit is given invalid name' do
-        let(:expected_max_length) { described_class::MAX_IDENTIFIER_NAME_LENGTH }
-        let(:expected_error_message) { "The maximum allowed constraint name is #{expected_max_length} characters" }
-
-        context 'when the explicit text limit name is not valid' do
-          it 'raises an error' do
-            too_long_length = expected_max_length + 1
-
-            expect do
-              migration.create_table table_name do |t|
-                t.timestamps_with_timezone
-                t.integer :some_id, null: false
-                t.boolean :active, null: false, default: true
-                t.text :name
-
-                t.text_limit :name, 255, name: ('a' * too_long_length)
-              end
-            end.to raise_error(expected_error_message)
-          end
-        end
+        expect_check_constraint(table_name, 'check_cda6f69506', 'char_length(name) <= 100')
       end
     end
   end

spec/rubocop/cop/migration/add_limit_to_text_columns_spec.rb

@@ -11,6 +11,7 @@ RSpec.describe RuboCop::Cop::Migration::AddLimitToTextColumns do
 
     before do
       allow(cop).to receive(:in_migration?).and_return(true)
+      allow(cop).to receive(:version).and_return(described_class::TEXT_LIMIT_ATTRIBUTE_ALLOWED_SINCE + 5)
     end
 
     context 'when text columns are defined without a limit' do
@@ -63,11 +64,8 @@ RSpec.describe RuboCop::Cop::Migration::AddLimitToTextColumns do
 
               create_table :test_text_limits_create do |t|
                 t.integer :test_id, null: false
-                t.text :title
-                t.text :description
-
-                t.text_limit :title, 100
-                t.text_limit :description, 255
+                t.text :title, limit: 100
+                t.text :description, limit: 255
               end
 
               add_column :test_text_limits, :email, :text
@@ -82,6 +80,30 @@ RSpec.describe RuboCop::Cop::Migration::AddLimitToTextColumns do
           end
         RUBY
       end
+
+      context 'for migrations before 2021_09_10_00_00_00' do
+        it 'when limit: attribute is used (which is not supported yet for this version): registers an offense' do
+          allow(cop).to receive(:version).and_return(described_class::TEXT_LIMIT_ATTRIBUTE_ALLOWED_SINCE - 5)
+
+          expect_offense(<<~RUBY)
+            class TestTextLimits < ActiveRecord::Migration[6.0]
+              def up
+                create_table :test_text_limit_attribute do |t|
+                  t.integer :test_id, null: false
+                  t.text :name, limit: 100
+                    ^^^^ Text columns should always have a limit set (255 is suggested). Using limit: is not supported in this version. You can add a limit to a `text` column by using `add_text_limit` or `.text_limit` inside `create_table`
+                end
+
+                create_table_with_constraints :test_text_limit_attribute do |t|
+                  t.integer :test_id, null: false
+                  t.text :name, limit: 100
+                    ^^^^ Text columns should always have a limit set (255 is suggested). Using limit: is not supported in this version. You can add a limit to a `text` column by using `add_text_limit` or `.text_limit` inside `create_table`
+                end
+              end
+            end
+          RUBY
+        end
+      end
     end
 
     context 'when text array columns are defined without a limit' do