add column type

app/models/column.rb

@@ -27,4 +27,8 @@ class Column
       table:, column:, label:, classname:, type:, scope:, value_column:, filterable:, displayable:
     }
   end
+
+  def self.find(h_id)
+    Procedure.with_discarded.find(h_id[:procedure_id]).find_column(h_id:)
+  end
 end

app/types/column_type.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+class ColumnType < ActiveRecord::Type::Value
+  # value can come from:
+  # setter: column (Column),
+  # form_input: column.id == { procedure_id:, column_id: }.to_json (String),
+  # from db: { procedure_id:, column_id: } (Hash)
+  def cast(value)
+    case value
+    in NilClass
+      nil
+    in Column
+      value
+    # from form
+    in String => id
+      h_id = JSON.parse(id, symbolize_names: true)
+      Column.find(h_id)
+    # from db
+    in Hash => h_id
+      Column.find(h_id)
+    end
+  end
+
+  # db -> ruby
+  def deserialize(value) = cast(value)
+
+  # ruby -> db
+  def serialize(value)
+    case value
+    in NilClass
+      nil
+    in Column
+      JSON.generate(value.h_id)
+    else
+      raise ArgumentError, "Invalid value for Column serialization: #{value}"
+    end
+  end
+end

config/initializers/types.rb

@@ -1,7 +1,9 @@
 # frozen_string_literal: true
 
+require Rails.root.join("app/types/column_type")
 require Rails.root.join("app/types/export_item_type")
 
 ActiveSupport.on_load(:active_record) do
+  ActiveRecord::Type.register(:column, ColumnType)
   ActiveRecord::Type.register(:export_item, ExportItemType)
 end

spec/types/column_type_spec.rb

@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+describe ColumnType do
+  let(:type) { ColumnType.new }
+
+  describe 'cast' do
+    it 'from Column' do
+      column = Column.new(procedure_id: 1, table: 'table', column: 'column')
+      expect(type.cast(column)).to eq(column)
+    end
+
+    it 'from nil' do
+      expect(type.cast(nil)).to eq(nil)
+    end
+
+    describe 'from form' do
+      it 'with valid column id' do
+        column = Column.new(procedure_id: 1, table: 'table', column: 'column')
+
+        expect(Column).to receive(:find).with(column.h_id).and_return(column)
+        expect(type.cast(column.id)).to eq(column)
+      end
+
+      it 'with invalid column id' do
+        expect { type.cast('invalid') }.to raise_error(JSON::ParserError)
+
+        id = { procedure_id: 'invalid', column_id: 'nop' }.to_json
+        expect { type.cast(id) }.to raise_error(ActiveRecord::RecordNotFound)
+      end
+    end
+
+    describe 'from db' do
+      it 'with valid column id' do
+        column = Column.new(procedure_id: 1, table: 'table', column: 'column')
+        expect(Column).to receive(:find).with(column.h_id).and_return(column)
+        expect(type.cast(column.h_id)).to eq(column)
+      end
+
+      it 'with invalid column id' do
+        h_id = { procedure_id: 'invalid', column_id: 'nop' }
+        expect { type.cast(h_id) }.to raise_error(ActiveRecord::RecordNotFound)
+      end
+    end
+  end
+
+  describe 'deserialize' do
+    context 'with valid value' do
+      it 'works' do
+        column = Column.new(procedure_id: 1, table: 'table', column: 'column')
+        expect(Column).to receive(:find).with(column.h_id).and_return(column)
+
+        expect(type.deserialize(column.h_id)).to eq(column)
+      end
+    end
+  end
+
+  describe 'serialize' do
+    it 'with SortedColumn' do
+      column = Column.new(procedure_id: 1, table: 'table', column: 'column')
+      expect(type.serialize(column)).to eq(column.h_id.to_json)
+    end
+
+    it 'with nil' do
+      expect(type.serialize(nil)).to eq(nil)
+    end
+
+    it 'with invalid value' do
+      expect { type.serialize('invalid') }.to raise_error(ArgumentError)
+    end
+  end
+end