X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/04cc77648cc62c73433801475c27ede4ceb76c8b..a934fcf84acd4cc3a351fde1b6e21a0bd93757ef:/services/api/lib/load_param.rb

diff --git a/services/api/lib/load_param.rb b/services/api/lib/load_param.rb
index f1c3198b0e..3f1a3b223a 100644
--- a/services/api/lib/load_param.rb
+++ b/services/api/lib/load_param.rb
@@ -1,10 +1,18 @@
+# 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
+
+  # Maximum number of rows to return in a single query, even if the client asks for more.
+  MAX_LIMIT = 1000
+
+  # Load params[:where] into @where
   def load_where_param
     if params[:where].nil? or params[:where] == ""
       @where = {}
@@ -21,6 +29,7 @@ module LoadParam
     @where = @where.with_indifferent_access
   end
 
+  # Load params[:filters] into @filters
   def load_filters_param
     @filters ||= []
     if params[:filters].is_a? Array
@@ -28,12 +37,109 @@ module LoadParam
     elsif params[:filters].is_a? String and !params[:filters].empty?
       begin
         f = Oj.load params[:filters]
-        raise unless f.is_a? Array
-        @filters += f
+        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
 
+  def default_orders
+    ["#{table_name}.modified_at desc"]
+  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+$/)
+        raise ArgumentError.new("Invalid value for limit parameter")
+      end
+      @limit = [params[:limit].to_i, MAX_LIMIT].min
+    else
+      @limit = DEFAULT_LIMIT
+    end
+
+    if params[:offset]
+      unless params[:offset].to_s.match(/^\d+$/)
+        raise ArgumentError.new("Invalid value for offset parameter")
+      end
+      @offset = params[:offset].to_i
+    else
+      @offset = 0
+    end
+
+    @orders = []
+    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.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
+          # $2 is of course the actual database column name
+          @orders << "#{attr} #{direction.downcase}"
+        end
+      end
+    end
+
+    if @orders.empty?
+      @orders = default_orders
+    end
+
+    case params[:select]
+    when Array
+      @select = params[:select]
+    when String
+      begin
+        @select = Oj.load params[:select]
+        raise unless @select.is_a? Array or @select.nil?
+      rescue
+        raise ArgumentError.new("Could not parse \"select\" param as an array")
+      end
+    end
+
+    if @select
+      # Any ordering columns must be selected when doing select,
+      # otherwise it is an SQL error, so filter out invaliding orderings.
+      @orders.select! { |o|
+        # match select column against order array entry
+        @select.select { |s| /^#{table_name}.#{s}( (asc|desc))?$/.match o }.any?
+      }
+    end
+
+    @distinct = true if (params[:distinct] == true || params[:distinct] == "true")
+    @distinct = false if (params[:distinct] == false || params[:distinct] == "false")
+  end
+
 end