WIP: fix read_value method in Administrate::Field::Base

lib/administrate/field/base.rb

@@ -34,11 +34,10 @@ def self.permitted_attribute(attr, _options = nil)
 
       def initialize(attribute, data, page, options = {})
         @attribute = attribute
-        @data = data
         @page = page
         @resource = options.delete(:resource)
         @options = options
-        @data = read_value if @data.nil?
+        @data = read_value(data)
       end
 
       def html_class
@@ -53,15 +52,19 @@ def name
         attribute.to_s
       end
 
-      def read_value
+      def read_value(data = nil)
         if options.key?(:getter)
           if options[:getter].respond_to?(:call)
             options[:getter].call(self)
           else
             resource&.public_send(options[:getter])
           end
         else
-          resource&.public_send(attribute)
+          if data.nil?
+            resource&.public_send(attribute)
+          else
+            data
+          end
         end
       end
 

spec/lib/fields/base_spec.rb

@@ -184,11 +184,10 @@
     end
 
     it "reads the value from the resource with a custom getter block" do
-      resource = double
+      resource = double("Model", custom_getter: "value")
       field = field_class.new(:attribute, :date, :page, resource: resource, getter: ->(field) { field.resource.custom_getter })
 
       expect(resource).to receive(:custom_getter)
-      field.read_value
     end
 
     it "returns nil if the resource is nil" do

spec/lib/fields/virtual_field_spec.rb

@@ -0,0 +1,38 @@
+require "rails_helper"
+require "administrate/field/base"
+
+module Administrate
+  module Field
+    class VirtualField < Field::Base
+      def self.searchable?
+        false
+      end
+
+      def read_value(data = nil)
+        resource.inspect
+      end
+
+      def foobar
+        "This is a Foobar: #{data}"
+      end
+    end
+  end
+end
+
+describe Administrate::Field::VirtualField do
+
+  describe "#foobar" do
+    it "displays the foobar" do
+      resource = double('Model', inspect: 'Inspecting')
+
+      field = Administrate::Field::VirtualField.new(
+        :virtual_field,
+        nil,
+        :show,
+        resource: resource
+      )
+
+      expect(field.foobar).to eq("This is a Foobar: Inspecting")
+    end
+  end
+end