Raise a descriptive error from store_accessor if the column is not …

…a Store

If a developer has neglected to use a structured column type (hstore
or json) or to declare a serializer with `ActiveRecord.store`:

```ruby
class User < ActiveRecord::Base
  store_accessor :settings, :notifications
end
```

then a `ConfigurationError` will now be raised by `store_accessor`
with a descriptive error message:

    ActiveRecord::ConfigurationError: the column 'settings' has not
    been configured as a store.  Please make sure the column is
    declared serializable via 'ActiveRecord.store' or, if your
    database supports it, use a structured column type like hstore or
    json.

Previously, in this situation, a `NoMethodError` was raised when the
accessor was read or written:

```ruby
puts user.notifications
```

Raising an exception earlier, with a helpful message, should help
developers understand more quickly what's wrong and how to fix it.

Note that this change makes `store_accessor` call `type_for_attribute`
which will potentially load the model's schema where it was not being
loaded before. As a result, some small changes were needed to the test
suite where the `json_data_type` table was not created early enough,
and where an anonymous class needed to be bound to a real table. I
don't think this should affect the majority of Store users.

Closes rails#51699

activerecord/CHANGELOG.md

@@ -1,3 +1,19 @@
+*   Improve `ActiveRecord.store_accessor` to raise an exception if the column is not either
+    structured (e.g., PostgreSQL +hstore+/+json+, or MySQL +json+) or declared serializable via
+    `ActiveRecord.store`.
+
+    Previously, an exception would be raised late when the accessor was read or written:
+
+        NoMethodError: undefined method `accessor' for an instance of ActiveRecord::Type::Text
+
+    Now, an exception is raised early when `store_accessor` is called:
+
+        ActiveRecord::ConfigurationError: the column 'metadata' has not been configured as a store.
+          Please make sure the column is declared serializable via 'ActiveRecord.store' or, if your
+          database supports it, use a structured column type like hstore or json.
+
+    *Mike Dalessio*
+
 *   Fix inference of association model on nested models with the same demodularized name.
 
     E.g. with the following setup:

activerecord/lib/active_record/store.rb

@@ -110,6 +110,10 @@ def store(store_attribute, options = {})
       end
 
       def store_accessor(store_attribute, *keys, prefix: nil, suffix: nil)
+        unless type_for_attribute(store_attribute).respond_to?(:accessor)
+          raise ConfigurationError, "the column '#{store_attribute}' has not been configured as a store. Please make sure the column is declared serializable via 'ActiveRecord.store' or, if your database supports it, use a structured column type like hstore or json."
+        end
+
         keys = keys.flatten
 
         accessor_prefix =

activerecord/test/cases/json_shared_test_cases.rb

@@ -3,6 +3,12 @@
 require "support/schema_dumping_helper"
 require "pp"
 
+# ensure we have a "json_data_type" table when JsonDataType is defined,
+# because store_accessor checks the column for a store accessor.
+ActiveRecord::Base.lease_connection.create_table("json_data_type") do |t|
+  t.json "settings"
+end
+
 module JSONSharedTestCases
   include SchemaDumpingHelper
 

activerecord/test/cases/store_test.rb

@@ -285,9 +285,13 @@ def test_convert_store_attributes_from_Hash_to_HashWithIndifferentAccess_saving_
 
   test "stored_attributes are tracked per class" do
     first_model = Class.new(ActiveRecord::Base) do
+      self.table_name = "admin_users"
+      store :data
       store_accessor :data, :color
     end
     second_model = Class.new(ActiveRecord::Base) do
+      self.table_name = "admin_users"
+      store :data
       store_accessor :data, :width, :height
     end
 
@@ -297,6 +301,8 @@ def test_convert_store_attributes_from_Hash_to_HashWithIndifferentAccess_saving_
 
   test "stored_attributes are tracked per subclass" do
     first_model = Class.new(ActiveRecord::Base) do
+      self.table_name = "admin_users"
+      store :data
       store_accessor :data, :color
     end
     second_model = Class.new(first_model) do
@@ -359,4 +365,12 @@ def test_convert_store_attributes_from_Hash_to_HashWithIndifferentAccess_saving_
   test "prefix/suffix do not affect stored attributes" do
     assert_equal [:secret_question, :two_factor_auth, :login_retry], Admin::User.stored_attributes[:configs]
   end
+
+  test "store_accessor raises an exception if the column is not either serializable or a structured type" do
+    assert_raises ActiveRecord::ConfigurationError do
+      Class.new(Admin::User) do
+        store_accessor :name, :color
+      end
+    end
+  end
 end