Add inspect_pk plugin to make it easier to retrieve model instance ba…

…sed on inspect output

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Add inspect_pk plugin to make it easier to retrieve model instance based on inspect output (jeremyevans)
+
 * Treat all Trilogy errors with error code 1205 as Sequel::DatabaseLockTimeout in the trilogy adapter (jeremyevans)
 
 * Allow Data{base,set}#extension to not require files if the extension is already registered (jeremyevans) (#2246)

lib/sequel/model/base.rb

@@ -1311,7 +1311,7 @@ def id
       # Returns a string representation of the model instance including
       # the class name and values.
       def inspect
-        "#<#{model.name} @values=#{inspect_values}>"
+        "#<#{inspect_prefix} @values=#{inspect_values}>"
       end
 
       # Returns the keys in +values+.  May not include all column names.
@@ -1994,7 +1994,12 @@ def initialize_set(h)
         set(h) unless h.empty?
       end
 
-      # Default inspection output for the values hash, overwrite to change what #inspect displays.
+      # Default inspect output for the inspect, by default, just showing the class.
+      def inspect_prefix
+        model.name
+      end
+
+      # Default inspect output for the values hash, overwrite to change what #inspect displays.
       def inspect_values
         @values.inspect
       end

lib/sequel/plugins/inspect_pk.rb

@@ -0,0 +1,44 @@
+# frozen-string-literal: true
+
+module Sequel
+  module Plugins
+    # The inspect_pk plugin includes the pk right next to the
+    # model name in inspect, allowing for easily copying and
+    # pasting to retrieve a copy of the object:
+    #
+    #   Album.with_pk(1).inspect
+    #   #         default: #<Album @values={...}>
+    #   # with inspect_pk: #<Album[1] @values={...}>
+    #
+    # Usage:
+    #
+    #   # Make all model instances include pk in inspect output
+    #   Sequel::Model.plugin :inspect_pk
+    #
+    #   # Make Album instances include pk in inspect output
+    #   Album.plugin :inspect_pk
+    module InspectPk
+      module InstanceMethods
+        private
+
+        # The primary key value to include in the inspect output, if any.
+        # For composite primary keys, this only includes a value if all
+        # fields are present.
+        def inspect_pk
+          if primary_key && (pk = self.pk) && (!(Array === pk) || pk.all?)
+            pk
+          end
+        end
+
+        # Include the instance's primary key in the output.
+        def inspect_prefix
+          if v = inspect_pk
+            "#{super}[#{v.inspect}]"
+          else
+            super
+          end
+        end
+      end
+    end
+  end
+end

spec/extensions/inspect_pk_spec.rb

@@ -0,0 +1,45 @@
+require_relative "spec_helper"
+
+describe "inspect_pk plugin" do
+  def inspect(vals={}, &block)
+    Class.new(Sequel::Model) do
+      def self.name; 'M' end
+      plugin :inspect_pk
+      set_dataset DB.dataset
+      class_exec(&block) if block
+      columns(*vals.keys)
+      unrestrict_primary_key
+    end.new(vals).inspect
+  end
+
+  it "should not include primary key value if model does not have primary key" do
+    inspect(id: 1){no_primary_key}.must_equal "#<M @values=#{{:id=>1}.inspect}>"
+  end
+
+  it "should not include primary key value if model has scalar primary key and instance does not have primary key value" do
+    inspect{set_primary_key :id}.must_equal "#<M @values={}>"
+  end
+
+  it "should not include primary key value if model instance has composite primary key and instance does not have values for all primary key components" do
+    [{id1: 1, id2: nil}, {id1: nil, id2: 2}, {id1: nil, id2: nil}].each do |vals|
+      inspect(vals){set_primary_key [:id1, :id2]}.must_equal "#<M @values=#{vals.inspect}>"
+    end
+  end
+
+  it "should include primary value for scalar primary key if present" do
+    inspect(id: 1){set_primary_key :id}.must_equal "#<M[1] @values=#{{id: 1}.inspect}>"
+  end
+
+  it "should include primary value for composite primary key if all fields present" do
+    vals = {id1: 1, id2: 2}
+    inspect(vals){set_primary_key [:id1, :id2]}.must_equal "#<M[[1, 2]] @values=#{vals.inspect}>"
+  end
+
+  it "should use inspect value of primary key" do
+    inspect(id: "1"){}.must_equal "#<M[\"1\"] @values=#{{id: "1"}.inspect}>"
+  end
+
+  it "should use inspect_pk method to get inspect pk value" do
+    inspect{def inspect_pk; "2" end}.must_equal "#<M[\"2\"] @values={}>"
+  end
+end

www/pages/plugins.html.erb

@@ -455,6 +455,10 @@
 <span class="ul__span">Adds Model.finder and Model.prepared_finder methods for defining optimized lookup methods.</span>
 </li>
 <li class="ul__li ul__li--grid">
+<a class="a" href="rdoc-plugins/classes/Sequel/Plugins/InspectPk.html">inspect_pk </a>
+<span class="ul__span">Makes it easier to retrieve model instance based on inspect output.</span>
+</li>
+<li class="ul__li ul__li--grid">
 <a class="a" href="rdoc-plugins/classes/Sequel/Plugins/List.html">list </a>
 <span class="ul__span">Allows you to treat model objects as being part of a list, so you can move them up/down and get next/previous entries.</span>
 </li>