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rails--rails/activerecord/test
Matt Yoho f41825809c Add Relation#annotate for SQL commenting
This patch has two main portions:

1. Add SQL comment support to Arel via Arel::Nodes::Comment.
2. Implement a Relation#annotate method on top of that.

== Adding SQL comment support

Adds a new Arel::Nodes::Comment node that represents an optional SQL
comment and teachers the relevant visitors how to handle it.

Comment nodes may be added to the basic CRUD statement nodes and set
through any of the four (Select|Insert|Update|Delete)Manager objects.

For example:

    manager = Arel::UpdateManager.new
    manager.table table
    manager.comment("annotation")
    manager.to_sql # UPDATE "users" /* annotation */

This new node type will be used by ActiveRecord::Relation to enable
query annotation via SQL comments.

== Implementing the Relation#annotate method

Implements `ActiveRecord::Relation#annotate`, which accepts a comment
string that will be appeneded to any queries generated by the relation.

Some examples:

    relation = Post.where(id: 123).annotate("metadata string")
    relation.first
    # SELECT "posts".* FROM "posts" WHERE "posts"."id" = 123
    # LIMIT 1 /* metadata string */

    class Tag < ActiveRecord::Base
      scope :foo_annotated, -> { annotate("foo") }
    end
    Tag.foo_annotated.annotate("bar").first
    # SELECT "tags".* FROM "tags" LIMIT 1 /* foo */ /* bar */

Also wires up the plumbing so this works with `#update_all` and
`#delete_all` as well.

This feature is useful for instrumentation and general analysis of
queries generated at runtime.
2019-03-21 20:30:56 -07:00
..
active_record/connection_adapters
assets
cases Add Relation#annotate for SQL commenting 2019-03-21 20:30:56 -07:00
fixtures
migrations
models Add Relation#annotate for SQL commenting 2019-03-21 20:30:56 -07:00
schema Add insert_all to ActiveRecord models (#35077) 2019-03-05 11:16:44 -08:00
support Remove duplicated protected params definitions 2019-02-24 19:50:53 +09:00
config.example.yml
config.rb