Handle ActiveRecord table name prefix and suffix

ActiveRecord allows you to set `table_name_prefix` and
`table_name_suffix` both via configuration (which ultimately sets the
options on `ActiveRecord::Base`) and in any subclass of ActiveRecord.
When set in configuration or directly on `ActiveRecord::Base`, rails
migrations and the schema dumper make the setting transparent to
migrations, `schema.rb`, etc.

For example, if I run the following:

```
ActiveRecord::Base.table_name_prefix = "api_"

class CreateUsers < ActiveRecord::Migration[7.0]
  def change
    create_table :users
  end
end
```

then the table that is created in the database is `app_users`, but
`schema.rb` calls the table `users`. If the user runs `rake
db:schema:load` then the table is created as `app_users` once again.
Setting the prefix or suffix in any way other than in configuration or
directly on `ActiveRecord::Base` does not influence schema generation at
all.

Prior to this change, Scenic didn't handle this situation at all. If you
had a prefix set and tried to run `create_view :searches` Scenic would
fail looking for the file `app_searches_v01.sql`. It turns out, rails
migrations mutate the arguments to most every method call automatically.
See: https://github.com/rails/rails/blob/4607108f91881cd1c24285dca63dc8e0f3f8a4f1/activerecord/lib/active_record/migration.rb#L917-L933

To get around this, I added `Scenic::UnaffixedName` so we could reverse
this process. This is essentially a copy of what Rails itself does in
its own schema dumper here: https://github.com/rails/rails/blob/4607108f91881cd1c24285dca63dc8e0f3f8a4f1/activerecord/lib/active_record/schema_dumper.rb#L295-L299

By unaffixing the view name in two places, we're able to fully support
table name prefix and suffix. This was probably more investigative work
than was warranted for this edge case feature, but I dove in thinking it
was going to be easy and now here we are...

Fixes #295

lib/scenic.rb

@@ -5,6 +5,7 @@
 require "scenic/railtie"
 require "scenic/schema_dumper"
 require "scenic/statements"
+require "scenic/unaffixed_name"
 require "scenic/version"
 require "scenic/view"
 require "scenic/index"

lib/scenic/definition.rb

@@ -2,7 +2,7 @@ module Scenic
   # @api private
   class Definition
     def initialize(name, version)
-      @name = name
+      @name = name.to_s
       @version = version.to_i
     end
 
@@ -28,8 +28,10 @@ def version
 
     private
 
+    attr_reader :name
+
     def filename
-      "#{@name.to_s.tr('.', '_')}_v#{version}.sql"
+      "#{UnaffixedName.for(name).tr('.', '_')}_v#{version}.sql"
     end
   end
 end

lib/scenic/unaffixed_name.rb

@@ -0,0 +1,31 @@
+module Scenic
+  # The name of a view or table according to rails.
+  #
+  # This removes any table name prefix or suffix that is configured via
+  # ActiveRecord. This allows, for example, the SchemaDumper to dump a view with
+  # its unaffixed name, consistent with how rails handles table dumping.
+  class UnaffixedName
+    # Gets the unaffixed name for the provided string
+    # @return [String]
+    #
+    # @param name [String] The (potentially) affixed view name
+    def self.for(name)
+      new(name, config: ActiveRecord::Base).call
+    end
+
+    def initialize(name, config:)
+      @name = name
+      @config = config
+    end
+
+    def call
+      prefix = Regexp.escape(config.table_name_prefix)
+      suffix = Regexp.escape(config.table_name_suffix)
+      name.sub(/\A#{prefix}(.+)#{suffix}\z/, "\\1")
+    end
+
+    private
+
+    attr_reader :name, :config
+  end
+end

lib/scenic/view.rb

@@ -45,7 +45,7 @@ def to_schema
       materialized_option = materialized ? "materialized: true, " : ""
 
       <<-DEFINITION
-  create_view #{name.inspect}, #{materialized_option}sql_definition: <<-\SQL
+  create_view #{UnaffixedName.for(name).inspect}, #{materialized_option}sql_definition: <<-\SQL
     #{definition.indent(2)}
   SQL
       DEFINITION

spec/scenic/definition_spec.rb

@@ -35,6 +35,14 @@ module Scenic
 
         expect(definition.path).to eq "db/views/non_public_searches_v01.sql"
       end
+
+      it "handles active record view prefix and suffixing" do
+        with_affixed_tables(prefix: "foo_", suffix: "_bar") do
+          definition = Definition.new("foo_searches_bar", 1)
+
+          expect(definition.path).to eq "db/views/searches_v01.sql"
+        end
+      end
     end
 
     describe "full_path" do

spec/scenic/schema_dumper_spec.rb

@@ -55,6 +55,20 @@ class SearchInAHaystack < ActiveRecord::Base
     end
   end
 
+  it "handles active record table name prefixes and suffixes" do
+    with_affixed_tables(prefix: "a_", suffix: "_z") do
+      view_definition = "SELECT 'needle'::text AS haystack"
+      Search.connection.create_view :a_searches_z, sql_definition: view_definition
+      stream = StringIO.new
+
+      ActiveRecord::SchemaDumper.dump(Search.connection, stream)
+
+      output = stream.string
+
+      expect(output).to include 'create_view "searches"'
+    end
+  end
+
   it "ignores tables internal to Rails" do
     view_definition = "SELECT 'needle'::text AS haystack"
     Search.connection.create_view :searches, sql_definition: view_definition

spec/spec_helper.rb

@@ -2,12 +2,14 @@
 require "database_cleaner"
 
 require File.expand_path("dummy/config/environment", __dir__)
+require "support/rails_configuration_helpers"
 require "support/generator_spec_setup"
 require "support/view_definition_helpers"
 
 RSpec.configure do |config|
   config.order = "random"
   config.include ViewDefinitionHelpers
+  config.include RailsConfigurationHelpers
   DatabaseCleaner.strategy = :transaction
 
   config.around(:each, db: true) do |example|

spec/support/rails_configuration_helpers.rb

@@ -0,0 +1,10 @@
+module RailsConfigurationHelpers
+  def with_affixed_tables(prefix: "", suffix: "")
+    ActiveRecord::Base.table_name_prefix = prefix
+    ActiveRecord::Base.table_name_suffix = suffix
+    yield
+  ensure
+    ActiveRecord::Base.table_name_prefix = ""
+    ActiveRecord::Base.table_name_suffix = ""
+  end
+end