Warn by default if trying to eager_graph/association_join an associat…

…ion that uses a block, when the block would be ignored

The auto_restrict_eager_graph plugin raises an error in these
cases.  That will be the default behavior in Sequel 6, but until
then, warn in this case so users know they should fix this.

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Warn by default if trying to eager_graph/association_join an association that uses a block, when the block would be ignored (jeremyevans)
+
 * Speed up validates_unique in validation_helpers plugin by using empty? instead of count == 0 (numbata) (#2122)
 
 * Speed up regexp matches in sqlite adapter on Ruby 2.4+ (jeremyevans)

lib/sequel/model/associations.rb

@@ -3387,8 +3387,15 @@ def eager_graph_association(ds, model, ta, requirements, r, *associations)
           local_opts = ds.opts[:eager_graph][:local]
           limit_strategy = r.eager_graph_limit_strategy(local_opts[:limit_strategy])
 
-          if r[:conditions] && !Sequel.condition_specifier?(r[:conditions]) && !r[:orig_opts].has_key?(:graph_conditions) && !r[:orig_opts].has_key?(:graph_only_conditions) && !r.has_key?(:graph_block)
-            raise Error, "Cannot eager_graph association when :conditions specified and not a hash or an array of pairs.  Specify :graph_conditions, :graph_only_conditions, or :graph_block for the association.  Model: #{r[:model]}, association: #{r[:name]}"
+          # SEQUEL6: remove and integrate the auto_restrict_eager_graph plugin
+          if !r[:orig_opts].has_key?(:graph_conditions) && !r[:orig_opts].has_key?(:graph_only_conditions) && !r.has_key?(:graph_block) && !r[:allow_eager_graph]
+            if r[:conditions] && !Sequel.condition_specifier?(r[:conditions])
+              raise Error, "Cannot eager_graph association when :conditions specified and not a hash or an array of pairs.  Specify :graph_conditions, :graph_only_conditions, or :graph_block for the association.  Model: #{r[:model]}, association: #{r[:name]}"
+            end
+
+            if r[:block] && !r[:graph_use_association_block]
+              warn "eager_graph used for association when association given a block without graph options.  The block is ignored in this case.  This will result in an exception starting in Sequel 6.  Model: #{r[:model]}, association: #{r[:name]}"
+            end
           end
 
           ds = loader.call(:self=>ds, :table_alias=>assoc_table_alias, :implicit_qualifier=>(ta == ds.opts[:eager_graph][:master]) ? first_source : qualifier_from_alias_symbol(ta, first_source), :callback=>callback, :join_type=>join_type || local_opts[:join_type], :join_only=>local_opts[:join_only], :limit_strategy=>limit_strategy, :from_self_alias=>ds.opts[:eager_graph][:master])

spec/model/eager_loading_spec.rb

@@ -1863,6 +1863,14 @@ def columns; literal(opts[:select]) =~ /x_foreign_key_x/ ? [:id, :x_foreign_key_
     proc{c.eager_graph(:genres)}.must_raise Sequel::Error
   end
 
+  it "should warn when using eager_graph with association with block" do
+    c = Class.new(GraphAlbum)
+    c.many_to_many :genres, :clone=>:genres, :join_table=>Sequel[:ag].as(:ga) do |ds| ds end
+    m = nil
+    c.dataset.with_extend{define_method(:warn){|msg| m = msg}}.eager_graph(:genres)
+    m.must_include 'eager_graph used for association when association given a block without graph options.  The block is ignored in this case.  This will result in an exception starting in Sequel 6'
+  end
+
   with_symbol_splitting "should correctly handle an aliased join table symbol in many_to_many and one_through_one" do
     c = Class.new(GraphAlbum)
     c.many_to_many :genres, :clone=>:genres, :join_table=>:ag___ga