From 86972f41cc34e9835f4d077282b93c74426c151c Mon Sep 17 00:00:00 2001
From: jbranchaud <jbranchaud@gmail.com>
Date: Wed, 20 Nov 2024 10:10:04 -0600
Subject: [PATCH] Add Set Default As SQL Function In Migration as a Rails TIL

---
 .vimrc                                        | 12 +++++
 README.md                                     |  3 +-
 ...et-default-as-sql-function-in-migration.md | 52 +++++++++++++++++++
 3 files changed, 66 insertions(+), 1 deletion(-)
 create mode 100644 rails/set-default-as-sql-function-in-migration.md

diff --git a/.vimrc b/.vimrc
index 6989dbc..f4beaf4 100644
--- a/.vimrc
+++ b/.vimrc
@@ -9,3 +9,15 @@ function! CountTILs()
 endfunction
 
 nnoremap <leader>c :call CountTILs()<cr>
+
+augroup DisableMarkdownFormattingForTILReadme
+    autocmd!
+    autocmd BufRead ~/code/til/README.md autocmd! Format
+augroup END
+
+" local til_readme_group = vim.api.nvim_create_augroup('DisableMarkdownFormattingForTILReadme', { clear = true })
+" vim.api.nvim_create_autocmd('BufRead', {
+"   command = 'autocmd! Format',
+"   group = til_readme_group,
+"   pattern = vim.fn.expand '~/code/til/README.md',
+" })
diff --git a/README.md b/README.md
index 9129e6d..26257a7 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1511 TILs and counting..._
+_1512 TILs and counting..._
 
 ---
 
@@ -1020,6 +1020,7 @@ _1511 TILs and counting..._
 - [Serialize With fast_jsonapi In A Rails App](rails/serialize-with-fast-jsonapi-in-a-rails-app.md)
 - [Set A Timestamp Field To The Current Time](rails/set-a-timestamp-field-to-the-current-time.md)
 - [Set DateTime To Include Time Zone In Migrations](rails/set-datetime-to-include-time-zone-in-migrations.md)
+- [Set Default As SQL Function In Migration](rails/set-default-as-sql-function-in-migration.md)
 - [Set default_url_options For Entire Application](rails/set-default-url-options-for-entire-application.md)
 - [Set Schema Search Path](rails/set-schema-search-path.md)
 - [Set Statement Timeout For All Postgres Connections](rails/set-statement-timeout-for-all-postgres-connections.md)
diff --git a/rails/set-default-as-sql-function-in-migration.md b/rails/set-default-as-sql-function-in-migration.md
new file mode 100644
index 0000000..a6fa7bf
--- /dev/null
+++ b/rails/set-default-as-sql-function-in-migration.md
@@ -0,0 +1,52 @@
+# Set Default As SQL Function In Migration
+
+With static default values, like `0`, `true`, or `'pending'`, we can set them
+directly as the value of `default`.
+
+```ruby
+class CreateActionsTable < ActiveRecord::Migration[7.2]
+  def change
+    create_table :actions do |t|
+      t.string :status, default: 'pending'
+    end
+  end
+end
+```
+
+However, if we want our default value to be a SQL function like `now()`, we
+have to use a lambda.
+
+Let's extend the above example to see what that looks like:
+
+```ruby
+class CreateActionsTable < ActiveRecord::Migration[7.2]
+  def change
+    create_table :actions do |t|
+      t.string :status, default: 'pending'
+
+      t.column :created_at, :timestamptz, default: -> { 'now()' }, null: false
+    end
+  end
+end
+```
+
+If we need to alter the default of an existing table's column, we can do
+something like this:
+
+```ruby
+class AddDefaultTimestampsToActions < ActiveRecord::Migration[7.2]
+  def up
+    change_column_default :actions, :created_at, -> { "now()" }
+    change_column_default :actions, :updated_at, -> { "now()" }
+  end
+
+  def down
+    change_column_default :actions, :created_at, nil
+    change_column_default :actions, :updated_at, nil
+  end
+end
+```
+
+I believe this functionality is available to Rails 5.0 and later.
+
+[source](https://github.com/rails/rails/issues/27077#issuecomment-261155826)