Module: Queryfy

Extended by:
Configuration
Defined in:
lib/queryfy.rb,
lib/queryfy/version.rb

Constant Summary collapse

VERSION = 
"0.3.0"

Class Method Summary collapse

Methods included from Configuration

configuration, define_setting

Class Method Details

.add_order(arel_table, arel_query, orderstring) ⇒ Object 



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# File 'lib/queryfy.rb', line 121

def self.add_order(arel_table, arel_query, orderstring)
	# adds order conditions to the passed query

	# If we don't want to order, return the oridinal query
	return arel_query if orderstring.nil? || orderstring == ''

	# Split the fields we want to order on
	split = orderstring.split(',')
	
	# Determine how we want to order each field (asc or desc)
	split.each do |s|
			order_char = s[-1, 1]
			s.chop! if order_char == '+' || order_char == '-'
			next unless order_char == '+' || order_char == '-'
			field = Queryfy.get_arel_field(arel_table, s)
			order = :asc
			if order_char == '-'
					order = :desc
			end

			# Add the order as a string, since hash is unsupported with query
			arel_query = arel_query.order("#{field} #{order}")
	end
	return arel_query
end

.build_query(klass, querystring, orderstring, limit = 50, offset = 0) ⇒ Object

Actually builds the query



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# File 'lib/queryfy.rb', line 14

def self.build_query(klass, querystring, orderstring, limit = 50, offset = 0)
	limit = [max_limit, limit.to_i].min
	offset = offset.to_i
	# Handle empty and nil queries
	if (querystring.nil? || querystring == '')
			data = self.add_order(klass.arel_table, klass.limit(limit).offset(offset), orderstring)
		return {
			data: data,
			count: klass.all.count,
			limit: limit.to_i, offset: offset.to_i
		}
	end

	begin
		tree = FilterLexer::Parser.parse(querystring)
	rescue FilterLexer::ParseException => e
		raise FilterParseError, "Failed to parse querystring, #{ e.message }"
		return
	end

	# Build the query with pagination
	query = klass.arel_table.project(Arel.star).take(limit).skip(offset)

	cleaned_tree = self.clean_tree(tree)
	arel_tree = self.cleaned_to_arel(klass.arel_table, cleaned_tree)
	# If we want to actually query, add the conditions to query
	query = query.where(arel_tree) unless arel_tree.nil?
	query = self.add_order(klass.arel_table, query, orderstring)

	total = 0
	if arel_tree.nil?
		total = klass.all.count
	else
		countquery = klass.arel_table.project(klass.arel_table[klass.primary_key.to_sym].count.as('total')).where(arel_tree)
		results = klass.connection.execute(countquery.to_sql)
		if results.count == 0
			raise QueryfyError, 'Failed to select count, this should not happen'
		else
			total = results[0]['total']
		end
	end

	# Return the results
	return {data: klass.find_by_sql(query.to_sql), count: total.to_i, limit: limit.to_i, offset: offset.to_i}
end

.clean_tree(tree, input = []) ⇒ Object

Cleans the filterlexer tree Output is an array with either filterentries and operators, or an array of filterentries and operators The latter represents a group



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# File 'lib/queryfy.rb', line 63

def self.clean_tree(tree, input = [])
	tree.elements.each do |el|
		if el.is_a?(FilterLexer::Expression)
			input += clean_tree(el)
		elsif el.is_a?(FilterLexer::Group)
			input += [clean_tree(el)]
		else
			input.push(el)
		end
	end
	return input
end

.cleaned_to_arel(arel_table, tree, ast = nil) ⇒ Object

Converts a cleaned tree to something arel can understand



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# File 'lib/queryfy.rb', line 77

def self.cleaned_to_arel(arel_table, tree, ast = nil)
	tree.each_with_index do |el, idx|
		next if el.is_a?(FilterLexer::LogicalOperator)
		operator = nil
		operator = tree[idx - 1] if idx > 0
		if el.is_a?(Array)
			ast = join_ast(ast, arel_table.grouping(cleaned_to_arel(arel_table, el)), operator)
		else
			ast = join_ast(ast, el.to_arel(arel_table), operator)
		end
	end

	return ast
end

.from_queryparams(klass, queryparams) ⇒ Object 



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# File 'lib/queryfy.rb', line 105

def self.from_queryparams(klass, queryparams)
	filter = ''
	offset = 0
	order = ''
	limit = Queryfy::default_limit
	if (queryparams.is_a?(Hash))
		filter = queryparams['filter'] unless queryparams['filter'].nil?
		offset = queryparams['offset'] unless queryparams['offset'].nil?
		limit = queryparams['limit'] unless queryparams['limit'].nil?
		order = queryparams['order'] unless queryparams['order'].nil?
	elsif(queryparams.is_a?(String))
		filter = queryparams
	end
	return Queryfy.build_query(klass, filter, order, limit, offset)
end

.get_arel_field(arel_table, field) ⇒ Object 



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# File 'lib/queryfy.rb', line 147

def self.get_arel_field(arel_table, field)
	# Check if the field we want to filter on exists
	field_index = arel_table.engine.column_names.index(field)
	arel_field = nil

	# Field does not exist, fail
	if field_index.nil?
		raise NoSuchFieldError.new("Unknown field #{ field }", field)
	else
		# Get the arel field name from our input, just to make sure
		# there is nothing weird is in the input
		arel_field = arel_table.engine.column_names[field_index]
	end
	return arel_field
end

.join_ast(ast, nodes, operator) ⇒ Object

Merges an existing ast with the passed nodes and uses the operator as a merge operator



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# File 'lib/queryfy.rb', line 93

def self.join_ast(ast, nodes, operator)
	if ast.nil? && !operator.nil?
		raise InvalidFilterFormat, "Cannot join on nil tree with operator near #{operator.text_value}"
	end
	if operator.nil? || ast.nil?
		ast = nodes
	else
		ast = ast.send(operator.to_arel, nodes)
	end
	return ast
end