Add pretty print support (#5810)

* Add pretty print support

This adds the `pretty_print` method, which pretty prints the same information as the `inspect` method. This is meant to be called by the default 'pp' gem, e.g. by calling `pp(person)` or `person.pretty_inspect`.

The specs are an almost identical to the specs for the `inspect` method to ensure the same information is included.

* Simplify code with if modifier

Co-authored-by: Jamis Buck <[email protected]>

* Avoid "default gem" terminology

Co-authored-by: Jamis Buck <[email protected]>

---------

Co-authored-by: Jamis Buck <[email protected]>
Co-authored-by: Jamis Buck <[email protected]>

lib/mongoid/inspectable.rb

@@ -19,6 +19,37 @@ def inspect
       "#<#{self.class.name} _id: #{_id}, #{inspection * ', '}>"
     end
 
+    # This pretty prints the same information as the inspect method. This is
+    # meant to be called by the standard 'pp' library.
+    #
+    # @param [ PP ] pretty_printer The pretty printer.
+    #
+    # @example Pretty print the document.
+    #   person.pretty_inspect
+    #
+    # @api private
+    def pretty_print(pretty_printer)
+      keys = fields.keys | attributes.keys
+      pretty_printer.group(1, "#<#{self.class.name}", '>') do
+        sep = lambda { pretty_printer.text(',') }
+        pretty_printer.seplist(keys, sep) do |key|
+          pretty_printer.breakable
+          field = fields[key]
+          as = "(#{field.options[:as]})" if field && field.options[:as]
+          pretty_printer.text("#{key}#{as}")
+          pretty_printer.text(':')
+          pretty_printer.group(1) do
+            pretty_printer.breakable
+            if key == "_id"
+              pretty_printer.text(_id.to_s)
+            else
+              pretty_printer.pp(@attributes[key])
+            end
+          end
+        end
+      end
+    end
+
     private
 
     # Get an array of inspected fields for the document.

spec/mongoid/inspectable_spec.rb

@@ -84,4 +84,84 @@
       end
     end
   end
+
+  describe "#pretty_inspect" do
+
+    context "when not allowing dynamic fields" do
+
+      let(:person) do
+        Person.new(title: "CEO")
+      end
+
+      let(:pretty_inspected) do
+        person.pretty_inspect
+      end
+
+      it "includes the model type" do
+        expect(pretty_inspected).to include("#<Person")
+      end
+
+      it "displays the id" do
+        expect(pretty_inspected).to include("_id: #{person.id}")
+      end
+
+      it "displays defined fields" do
+        expect(pretty_inspected).to include(%q,title: "CEO",)
+      end
+
+      it "displays field aliases" do
+        expect(pretty_inspected).to include("t(test):")
+      end
+
+      it "displays the default discriminator key" do
+        expect(pretty_inspected).to include(%q,_type: "Person",)
+      end
+    end
+
+    context "when using a custom discriminator key" do
+
+      before do
+        Person.discriminator_key = "dkey"
+      end
+
+      after do
+        Person.discriminator_key = nil
+      end
+
+      let(:person) do
+        Person.new(title: "CEO")
+      end
+
+      let(:pretty_inspected) do
+        person.pretty_inspect
+      end
+
+      it "displays the new discriminator key" do
+        expect(pretty_inspected).to include(%q,dkey: "Person",)
+      end
+    end
+
+    context "when allowing dynamic fields" do
+
+      let(:person) do
+        Person.new(title: "CEO", some_attribute: "foo")
+      end
+
+      let(:pretty_inspected) do
+        person.pretty_inspect
+      end
+
+      it "includes dynamic attributes" do
+        expect(pretty_inspected).to include(%q,some_attribute: "foo",)
+      end
+    end
+
+    context 'when id is unaliased' do
+      let(:shirt) { Shirt.new(id: 1, _id: 2) }
+
+      it 'shows the correct _id and id values' do
+        shirt.pretty_inspect.should == "#<Shirt _id: 2, color: nil, id: \"1\">\n"
+      end
+    end
+  end
 end