Merge branch 'dz-remove-namespaces-path-uniq' into 'master'

Modify namespace name and path validation

## What does this MR do?

* Allow same namespace name with different parent_id
* Allow same namespace path. Uniq validation should be handled by routes table

## Are there points in the code the reviewer needs to double check?

migrations

## Why was this MR needed?

So we can use same name in different nesting like: 

```
gitlab-ce/foo
gitlab-com/foo
foo/gitlab-ce
```

## Screenshots (if relevant)

no

## Does this MR meet the acceptance criteria?

- ~~[Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added~~
- ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~API support added~~
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/2772

See merge request !8013

app/models/namespace.rb

@@ -17,14 +17,13 @@ class Namespace < ActiveRecord::Base
   validates :owner, presence: true, unless: ->(n) { n.type == "Group" }
   validates :name,
     presence: true,
-    uniqueness: true,
+    uniqueness: { scope: :parent_id },
     length: { maximum: 255 },
     namespace_name: true
   validates :description, length: { maximum: 255 }
   validates :path,
     presence: true,
-    uniqueness: { case_sensitive: false },
     length: { maximum: 255 },
     namespace: true

db/migrate/20161206153749_remove_uniq_path_index_from_namespace.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class RemoveUniqPathIndexFromNamespace < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  DOWNTIME = false
+
+  def up
+    constraint_name = 'namespaces_path_key'
+
+    transaction do
+      if index_exists?(:namespaces, :path)
+        remove_index(:namespaces, :path)
+      end
+
+      # In some bizarre cases PostgreSQL might have a separate unique constraint
+      # that we'll need to drop.
+      if constraint_exists?(constraint_name) && Gitlab::Database.postgresql?
+        execute("ALTER TABLE namespaces DROP CONSTRAINT IF EXISTS #{constraint_name};")
+      end
+    end
+  end
+
+  def down
+    unless index_exists?(:namespaces, :path)
+      add_concurrent_index(:namespaces, :path, unique: true)
+    end
+  end
+
+  def constraint_exists?(name)
+    indexes(:namespaces).map(&:name).include?(name)
+  end
+end

db/migrate/20161206153751_add_path_index_to_namespace.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddPathIndexToNamespace < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  DOWNTIME = false
+
+  def up
+    add_concurrent_index :namespaces, :path
+  end
+
+  def down
+    if index_exists?(:namespaces, :path)
+      remove_index :namespaces, :path
+    end
+  end
+end

db/migrate/20161206153753_remove_uniq_name_index_from_namespace.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class RemoveUniqNameIndexFromNamespace < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  DOWNTIME = false
+
+  def up
+    constraint_name = 'namespaces_name_key'
+
+    transaction do
+      if index_exists?(:namespaces, :name)
+        remove_index(:namespaces, :name)
+      end
+
+      # In some bizarre cases PostgreSQL might have a separate unique constraint
+      # that we'll need to drop.
+      if constraint_exists?(constraint_name) && Gitlab::Database.postgresql?
+        execute("ALTER TABLE namespaces DROP CONSTRAINT IF EXISTS #{constraint_name};")
+      end
+    end
+  end
+
+  def down
+    unless index_exists?(:namespaces, :name)
+      add_concurrent_index(:namespaces, :name, unique: true)
+    end
+  end
+
+  def constraint_exists?(name)
+    indexes(:namespaces).map(&:name).include?(name)
+  end
+end

db/migrate/20161206153754_add_name_index_to_namespace.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddNameIndexToNamespace < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  DOWNTIME = false
+
+  def up
+    add_concurrent_index(:namespaces, [:name, :parent_id], unique: true)
+  end
+
+  def down
+    if index_exists?(:namespaces, :name)
+      remove_index :namespaces, [:name, :parent_id]
+    end
+  end
+end

db/schema.rb

@@ -744,11 +744,11 @@ ActiveRecord::Schema.define(version: 20161212142807) do
   add_index "namespaces", ["created_at"], name: "index_namespaces_on_created_at", using: :btree
   add_index "namespaces", ["deleted_at"], name: "index_namespaces_on_deleted_at", using: :btree
-  add_index "namespaces", ["name"], name: "index_namespaces_on_name", unique: true, using: :btree
+  add_index "namespaces", ["name", "parent_id"], name: "index_namespaces_on_name_and_parent_id", unique: true, using: :btree
   add_index "namespaces", ["name"], name: "index_namespaces_on_name_trigram", using: :gin, opclasses: {"name"=>"gin_trgm_ops"}
   add_index "namespaces", ["owner_id"], name: "index_namespaces_on_owner_id", using: :btree
   add_index "namespaces", ["parent_id", "id"], name: "index_namespaces_on_parent_id_and_id", unique: true, using: :btree
-  add_index "namespaces", ["path"], name: "index_namespaces_on_path", unique: true, using: :btree
+  add_index "namespaces", ["path"], name: "index_namespaces_on_path", using: :btree
   add_index "namespaces", ["path"], name: "index_namespaces_on_path_trigram", using: :gin, opclasses: {"path"=>"gin_trgm_ops"}
   add_index "namespaces", ["type"], name: "index_namespaces_on_type", using: :btree
@@ -1290,4 +1290,4 @@ ActiveRecord::Schema.define(version: 20161212142807) do
   add_foreign_key "subscriptions", "projects", on_delete: :cascade
   add_foreign_key "trending_projects", "projects", on_delete: :cascade
   add_foreign_key "u2f_registrations", "users"
-end
+end
\ No newline at end of file

spec/models/group_spec.rb

@@ -50,9 +50,8 @@ describe Group, models: true do
   describe 'validations' do
     it { is_expected.to validate_presence_of :name }
-    it { is_expected.to validate_uniqueness_of(:name) }
+    it { is_expected.to validate_uniqueness_of(:name).scoped_to(:parent_id) }
     it { is_expected.to validate_presence_of :path }
-    it { is_expected.to validate_uniqueness_of(:path) }
     it { is_expected.not_to validate_presence_of :owner }
   end

spec/models/namespace_spec.rb

@@ -6,20 +6,16 @@ describe Namespace, models: true do
   it { is_expected.to have_many :projects }
   it { is_expected.to validate_presence_of(:name) }
-  it { is_expected.to validate_uniqueness_of(:name) }
+  it { is_expected.to validate_uniqueness_of(:name).scoped_to(:parent_id) }
   it { is_expected.to validate_length_of(:name).is_at_most(255) }
   it { is_expected.to validate_length_of(:description).is_at_most(255) }
   it { is_expected.to validate_presence_of(:path) }
-  it { is_expected.to validate_uniqueness_of(:path) }
   it { is_expected.to validate_length_of(:path).is_at_most(255) }
   it { is_expected.to validate_presence_of(:owner) }
-  describe "Mass assignment" do
-  end
-
   describe "Respond to" do
     it { is_expected.to respond_to(:human_name) }
     it { is_expected.to respond_to(:to_param) }