make active_connection? return true only if there is an open connection in use for the current thread. fixes #5330

Last commit message should not have said 'Rails 4' either

This reverts commit fd584a63.

Reason: This is not suitable for a Rails guide in my opinion.

refactor Hash#slice and Hash#extract!

Change the message string to use in  test case.

Update CHANGELOG to fix wrong extension.

Fix has_many through associations when mass_assignment_sanitizer is strict

[Proposal] Schema cache dump

Reason: Temporarily reverting this because it has uncovered an issue that
prevents Sam's test suite from passing.

This reverts commit 9b2c38b7.

Reason: We are about to temporarily revert the change to the default.

This reverts commit 5c0aba23.

Add tests to test that through associations are not readonly, and we can update the records we retrive from the association

Enhance PostgreSQL Adapter schema support

Update ActiveRecord::AttributeMethods#attribute_present? to return false for empty strings

Correct "its" usage for "AJAX on Rails" page

Add test case for #5307

odd and even keys are not scoped by activerecord.

warning fix : mismatched indentations at 'end' with 'case'

path segment

Adds :layout option to render :partial when a collection is given.

Refactor ActionDispatch::UploadedFile