X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/995dd33ec5bc9ebb7cc4ff075a1f5e1a4e7db20c..9bd0009d81d3bcdb1b1b1b3ff070537b6ff68f54:/services/api/lib/load_param.rb

diff --git a/services/api/lib/load_param.rb b/services/api/lib/load_param.rb
index dba05825a7..5b22274d07 100644
--- a/services/api/lib/load_param.rb
+++ b/services/api/lib/load_param.rb
@@ -1,12 +1,15 @@
+# Mixin module for reading out query parameters from request params.
+#
 # Expects:
 #   +params+ Hash
 # Sets:
-#   @where, @filters
-
+#   @where, @filters, @limit, @offset, @orders
 module LoadParam
 
+  # Default number of rows to return in a single query.
   DEFAULT_LIMIT = 100
 
+  # Load params[:where] into @where
   def load_where_param
     if params[:where].nil? or params[:where] == ""
       @where = {}
@@ -14,7 +17,7 @@ module LoadParam
       @where = params[:where]
     elsif params[:where].is_a? String
       begin
-        @where = Oj.load(params[:where])
+        @where = Oj.strict_load(params[:where])
         raise unless @where.is_a? Hash
       rescue
         raise ArgumentError.new("Could not parse \"where\" param as an object")
@@ -23,27 +26,33 @@ module LoadParam
     @where = @where.with_indifferent_access
   end
 
+  # Load params[:filters] into @filters
   def load_filters_param
     @filters ||= []
     if params[:filters].is_a? Array
       @filters += params[:filters]
     elsif params[:filters].is_a? String and !params[:filters].empty?
       begin
-        f = Oj.load params[:filters]
-        raise unless f.is_a? Array
-        @filters += f
+        f = Oj.strict_load params[:filters]
+        if not f.nil?
+          raise unless f.is_a? Array
+          @filters += f
+        end
       rescue
         raise ArgumentError.new("Could not parse \"filters\" param as an array")
       end
     end
   end
 
+  # Load params[:limit], params[:offset] and params[:order]
+  # into @limit, @offset, @orders
   def load_limit_offset_order_params
     if params[:limit]
       unless params[:limit].to_s.match(/^\d+$/)
         raise ArgumentError.new("Invalid value for limit parameter")
       end
-      @limit = params[:limit].to_i
+      @limit = [params[:limit].to_i,
+                Rails.configuration.max_items_per_response].min
     else
       @limit = DEFAULT_LIMIT
     end
@@ -58,21 +67,99 @@ module LoadParam
     end
 
     @orders = []
-    if params[:order]
-      params[:order].split(',').each do |order|
+    if (params[:order].is_a?(Array) && !params[:order].empty?) || !params[:order].blank?
+      od = []
+      (case params[:order]
+       when String
+         if params[:order].starts_with? '['
+           od = Oj.strict_load(params[:order])
+           raise unless od.is_a? Array
+           od
+         else
+           params[:order].split(',')
+         end
+       when Array
+         params[:order]
+       else
+         []
+       end).each do |order|
+        order = order.to_s
         attr, direction = order.strip.split " "
         direction ||= 'asc'
+        # The attr can have its table unspecified if it happens to be for the current "model_class" (the first case)
+        # or it can be fully specified with the database tablename (the second case) (e.g. "collections.name").
+        # NB that the security check for the second case table_name will not work if the model
+        # has used set_table_name to use an alternate table name from the Rails standard.
+        # I could not find a perfect way to handle this well, but ActiveRecord::Base.send(:descendants)
+        # would be a place to start if this ever becomes necessary.
         if attr.match /^[a-z][_a-z0-9]+$/ and
             model_class.columns.collect(&:name).index(attr) and
             ['asc','desc'].index direction.downcase
           @orders << "#{table_name}.#{attr} #{direction.downcase}"
+        elsif attr.match /^([a-z][_a-z0-9]+)\.([a-z][_a-z0-9]+)$/ and
+            ['asc','desc'].index(direction.downcase) and
+            ActiveRecord::Base.connection.tables.include?($1) and
+            $1.classify.constantize.columns.collect(&:name).index($2)
+          # $1 in the above checks references the first match from the regular expression, which is expected to be the database table name
+          # $2 is of course the actual database column name
+          @orders << "#{attr} #{direction.downcase}"
         end
       end
     end
-    if @orders.empty?
-      @orders << "#{table_name}.modified_at desc"
+
+    # If the client-specified orders don't amount to a full ordering
+    # (e.g., [] or ['owner_uuid desc']), fall back on the default
+    # orders to ensure repeating the same request (possibly with
+    # different limit/offset) will return records in the same order.
+    #
+    # Clean up the resulting list of orders such that no column
+    # uselessly appears twice (Postgres might not optimize this out
+    # for us) and no columns uselessly appear after a unique column
+    # (Postgres does not optimize this out for us; as of 9.2, "order
+    # by id, modified_at desc, uuid" is slow but "order by id" is
+    # fast).
+    orders_given_and_default = @orders + model_class.default_orders
+    order_cols_used = {}
+    @orders = []
+    orders_given_and_default.each do |order|
+      otablecol = order.split(' ')[0]
+
+      next if order_cols_used[otablecol]
+      order_cols_used[otablecol] = true
+
+      @orders << order
+
+      otable, ocol = otablecol.split('.')
+      if otable == table_name and model_class.unique_columns.include?(ocol)
+        # we already have a full ordering; subsequent entries would be
+        # superfluous
+        break
+      end
     end
-  end
 
+    case params[:select]
+    when Array
+      @select = params[:select]
+    when String
+      begin
+        @select = Oj.strict_load params[:select]
+        raise unless @select.is_a? Array or @select.nil?
+      rescue
+        raise ArgumentError.new("Could not parse \"select\" param as an array")
+      end
+    end
+
+    if @select
+      # Any ordering columns must be selected when doing select,
+      # otherwise it is an SQL error, so filter out invaliding orderings.
+      @orders.select! { |o|
+        # match select column against order array entry
+        @select.select { |s| /^#{table_name}.#{s}( (asc|desc))?$/.match o }.any?
+      }
+    end
+
+    @distinct = true if (params[:distinct] == true || params[:distinct] == "true")
+    @distinct = false if (params[:distinct] == false || params[:distinct] == "false")
+  end
 
 end