added teh ability for filters/groups to do something on chain-creation

git-svn-id: https://dev.finn.de/svn/cockpit/branches/reporting_merge@1651 7926756e-e54e-46e6-9721-ed318f58905e

app/models/cost_query.rb

@@ -12,6 +12,10 @@ class CostQuery < ActiveRecord::Base
     @accepted_properties ||= []
   end
 
+  def self.chain_initializer
+    return @chain_initializer ||= []
+  end
+
   def available_filters
     CostQuery::Filter.all
   end
@@ -19,7 +23,7 @@ class CostQuery < ActiveRecord::Base
   def transformer
     @transformer ||= CostQuery::Transformer.new self
   end
-  
+
   def walker
     @walker ||= CostQuery::Walker.new self
   end
@@ -31,12 +35,20 @@ class CostQuery < ActiveRecord::Base
   end
 
   def chain(klass = nil, options = {})
-    @chain ||= Filter::NoFilter.new
+    build_new_chain unless @chain
     @chain = klass.new @chain, options if klass
     @chain = @chain.parent until @chain.top?
     @chain
   end
 
+  def build_new_chain
+    #FIXME: is there a better way to load all filter and groups?
+    Filter.all && GroupBy.all
+
+    @chain = Filter::NoFilter.new
+    self.class.chain_initializer.each { |block| block.call self }
+  end
+
   def filter(name, options = {})
     add_chain Filter, name, options
   end

app/models/cost_query/chainable.rb

@@ -60,6 +60,15 @@ class CostQuery < ActiveRecord::Base
       name.demodulize.underscore
     end
 
+    ##
+    # The given block is called when a new chain is created for a cost_query.
+    # The query will be given to the block as a parameter.
+    # Example:
+    # initialize_query_with { |query| query.filter CostQuery::Filter::City, :operators => '=', :values => 'Berlin, da great City' }
+    def self.initialize_query_with(&block)
+      CostQuery.chain_initializer.push block
+    end
+
     inherited_attribute :label
     inherited_attribute :properties, :list => true