Allow proc default values that depend on other values

lib/sequel/plugins/defaults_setter.rb

@@ -43,13 +43,13 @@ module Plugins
     #   album.values # => {}
     #   album.a
     #   album.values # => {:a => Date.today}
-    # 
+    #
     # Usage:
     #
     #   # Make all model subclass instances set defaults (called before loading subclasses)
     #   Sequel::Model.plugin :defaults_setter
     #
-    #   # Make the Album class set defaults 
+    #   # Make the Album class set defaults
     #   Album.plugin :defaults_setter
     module DefaultsSetter
       # Set the default values based on the model schema. Options:
@@ -76,7 +76,7 @@ module ClassMethods
         def cache_default_values?
           @cache_default_values
         end
-        
+
         # Freeze default values when freezing model class
         def freeze
           @default_values.freeze
@@ -133,7 +133,13 @@ module InstanceMethods
         def [](k)
           if new? && !values.has_key?(k)
             v = model.default_values.fetch(k){return}
-            v = v.call if v.respond_to?(:call)
+            if v.respond_to?(:call)
+              if v.arity == 1
+                v = v.call(self)
+              else
+                v = v.call
+              end
+            end
             values[k] = v if model.cache_default_values?
             v
           else

spec/extensions/defaults_setter_spec.rb

@@ -9,11 +9,11 @@ def db.supports_schema_parsing?() true end
     def db.schema(*) [] end
     db.singleton_class.send(:alias_method, :schema, :schema)
     @c = c = Class.new(Sequel::Model(db[:foo]))
-    @c.instance_variable_set(:@db_schema, {:a=>{}})
+    @c.instance_variable_set(:@db_schema, {:a=>{}, :b=>{}})
     @c.plugin :defaults_setter
-    @c.columns :a
+    @c.columns :a, :b
     @pr = proc do |x|
-      db.define_singleton_method(:schema){|*| [[:id, {:primary_key=>true}], [:a, {:ruby_default => x, :primary_key=>false}]]}
+      db.define_singleton_method(:schema){|*| [[:id, {:primary_key=>true}], [:a, {:ruby_default => x, :primary_key=>false}], [:b, {:primary_key=>false}]]}
       db.singleton_class.send(:alias_method, :schema, :schema)
       c.dataset = c.dataset; c
     end
@@ -181,6 +181,12 @@ def db.schema(*) [] end
     c.new.a.must_equal 2
   end
 
+  it "should allow proc default values that depend on other values" do
+    @pr.call(2)
+    @c.default_values[:a] = proc{ |instance| instance.b * 2 }
+    @c.new(b: 5).a.must_equal 10
+  end
+
   it "should set default value upon initialization when plugin loaded without dataset" do
     db = @db
     @c = c = Class.new(Sequel::Model)