Generators should raise an error if a field has an invalid type

Generators can create invalid migrations when passing an invalid
field type. For example, when mixing up the name and type:

    bin/rails g model post string:title

This will generate a field for post with a column named `string`
of the type `title`, instead of a column named `title` of the type
`string`. Running the migration will result in an error as the type
`title` is not known to the database.

Instead of generating invalid files, the generator should raise an error
if the type is invalid. We validate the type by checking if it's a
default migration types like: string, integer, datetime, but also
references, and rich_text.

If the type isn't a default type, we can ask the
database connection if the type is valid. This uses the `valid_type?`
method defined on each database adapter, which returns true if the
adapter supports the column type. This method is also used by the
SchemaDumper.

Some gems like 'postgis' add custom types. The 'postgis' gem adds these
types by overriding the `native_database_types` method.
That method is used by `valid_type?` method on the database adapter,
making this change compatible with 'postgis'.

railties/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Raise an error in generators if a field type is invalid.
+
+    *Petrik de Heus*
+
 *   `bin/rails tmp:clear` deletes also files and directories in `tmp/storage`.
 
     *George Claghorn*

railties/lib/rails/generators/generated_attribute.rb

@@ -7,6 +7,25 @@ module Generators
     class GeneratedAttribute # :nodoc:
       INDEX_OPTIONS = %w(index uniq)
       UNIQ_INDEX_OPTIONS = %w(uniq)
+      DEFAULT_TYPES = %w(
+        attachment
+        attachments
+        belongs_to
+        boolean
+        date
+        datetime
+        decimal
+        digest
+        float
+        integer
+        references
+        rich_text
+        string
+        text
+        time
+        timestamp
+        token
+      )
 
       attr_accessor :name, :type
       attr_reader   :attr_options
@@ -24,6 +43,10 @@ def parse(column_definition)
           type, attr_options = *parse_type_and_options(type)
           type = type.to_sym if type
 
+          if type && !valid_type?(type)
+            raise Error, "Could not generate field '#{name}' with unknown type '#{type}'."
+          end
+
           if type && reference?(type)
             if UNIQ_INDEX_OPTIONS.include?(has_index)
               attr_options[:index] = { unique: true }
@@ -33,6 +56,11 @@ def parse(column_definition)
           new(name, type, has_index, attr_options)
         end
 
+        def valid_type?(type)
+          DEFAULT_TYPES.include?(type.to_s) ||
+            ActiveRecord::Base.connection.valid_type?(type)
+        end
+
         def reference?(type)
           [:references, :belongs_to].include? type
         end

railties/test/generators/generated_attribute_test.rb

@@ -2,13 +2,15 @@
 
 require "generators/generators_test_helper"
 require "rails/generators/generated_attribute"
+require "rails/generators/base"
 
 class GeneratedAttributeTest < Rails::Generators::TestCase
   include GeneratorsTestHelper
 
   def setup
     @old_belongs_to_required_by_default = Rails.application.config.active_record.belongs_to_required_by_default
     Rails.application.config.active_record.belongs_to_required_by_default = true
+    ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
   end
 
   def teardown
@@ -57,10 +59,13 @@ def test_field_type_returns_file_field
     end
   end
 
-  def test_field_type_with_unknown_type_returns_text_field
-    %w(foo bar baz).each do |attribute_type|
-      assert_field_type attribute_type, :text_field
+  def test_field_type_with_unknown_type_raises_error
+    field_type = :unknown
+    e = assert_raise Rails::Generators::Error do
+      create_generated_attribute field_type
     end
+    message = "Could not generate field 'test' with unknown type 'unknown'"
+    assert_match message, e.message
   end
 
   def test_default_value_is_integer
@@ -109,7 +114,7 @@ def test_default_value_is_nil
   end
 
   def test_default_value_is_empty_string
-    %w(foo bar baz).each do |attribute_type|
+    %w(digest token).each do |attribute_type|
       assert_field_default_value attribute_type, ""
     end
   end
@@ -128,7 +133,7 @@ def test_reference_is_true
   end
 
   def test_reference_is_false
-    %w(foo bar baz).each do |attribute_type|
+    %w(string text float).each do |attribute_type|
       assert_not_predicate create_generated_attribute(attribute_type), :reference?
     end
   end
@@ -140,8 +145,8 @@ def test_polymorphic_reference_is_true
   end
 
   def test_polymorphic_reference_is_false
-    %w(foo bar baz).each do |attribute_type|
-      assert_not_predicate create_generated_attribute("#{attribute_type}{polymorphic}"), :polymorphic?
+    %w(references belongs_to).each do |attribute_type|
+      assert_not_predicate create_generated_attribute(attribute_type), :polymorphic?
     end
   end
 
@@ -163,6 +168,12 @@ def test_handles_column_names_for_references
     assert_equal "post_id", create_generated_attribute("belongs_to", "post").column_name
   end
 
+  def test_parse_works_with_adapter_specific_types
+    att = Rails::Generators::GeneratedAttribute.parse("document:json")
+    assert_equal "document", att.name
+    assert_equal :json, att.type
+  end
+
   def test_parse_required_attribute_with_index
     att = Rails::Generators::GeneratedAttribute.parse("supplier:references:index")
     assert_equal "supplier", att.name