# @where, @filters, @limit, @offset, @orders
module LoadParam
- # Default limit on number of rows to return in a single query.
+ # Default number of rows to return in a single query.
DEFAULT_LIMIT = 100
# Load params[:where] into @where
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
unless params[:limit].to_s.match(/^\d+$/)
raise ArgumentError.new("Invalid value for limit parameter")
end
- @limit = params[:limit].to_i
+ @limit = [params[:limit].to_i,
+ Rails.configuration.max_items_per_response].min
else
@limit = DEFAULT_LIMIT
end
end
@orders = []
- if params[:order]
+ if (params[:order].is_a?(Array) && !params[:order].empty?) || !params[:order].blank?
od = []
(case params[:order]
when String
order = order.to_s
attr, direction = order.strip.split " "
direction ||= 'asc'
+ # The attr can have its table unspecified if it happens to be for the current "model_class" (the first case)
+ # or it can be fully specified with the database tablename (the second case) (e.g. "collections.name").
+ # NB that the security check for the second case table_name will not work if the model
+ # has used set_table_name to use an alternate table name from the Rails standard.
+ # I could not find a perfect way to handle this well, but ActiveRecord::Base.send(:descendants)
+ # would be a place to start if this ever becomes necessary.
if attr.match /^[a-z][_a-z0-9]+$/ 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
+ # 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
case params[:select]
@distinct = false if (params[:distinct] == false || params[:distinct] == "false")
end
-
end
projects / arvados.git / blobdiff