module Arel
module SqlCompiler
class GenericCompiler
attr_reader :relation
def initialize(relation)
@relation = relation
@engine = relation.engine
end
def select_sql
if relation.projections.first.is_a?(Count) && relation.projections.size == 1 &&
(taken.present? || wheres.present?) && joins(self).blank?
subquery = build_query("SELECT 1 FROM #{from_clauses}", build_clauses)
query = "SELECT COUNT(*) AS count_id FROM (#{subquery}) AS subquery"
else
query = [
"SELECT #{relation.select_clauses.join(', ')}",
"FROM #{relation.from_clauses}",
build_clauses
].compact.join ' '
end
query
end
def build_clauses
joins = joins(self)
wheres = relation.where_clauses
groups = relation.group_clauses
havings = relation.having_clauses
orders = relation.order_clauses
clauses = [ "",
joins,
("WHERE #{wheres.join(' AND ')}" unless wheres.empty?),
("GROUP BY #{groups.join(', ')}" unless groups.empty?),
("HAVING #{havings.join(' AND ')}" unless havings.empty?),
("ORDER BY #{orders.join(', ')}" unless orders.empty?)
].compact.join ' '
offset = relation.skipped
limit = relation.taken
@engine.add_limit_offset!(clauses, :limit => limit,
:offset => offset) if offset || limit
clauses << " #{locked}" unless locked.blank?
clauses unless clauses.blank?
end
def delete_sql
build_query \
"DELETE",
"FROM #{table_sql}",
("WHERE #{wheres.collect(&:to_sql).join(' AND ')}" unless wheres.blank? ),
(add_limit_on_delete(taken) unless taken.blank? )
end
def add_limit_on_delete(taken)
"LIMIT #{taken}"
end
def insert_sql(include_returning = true)
insertion_attributes_values_sql = if record.is_a?(Value)
record.value
else
attributes = record.keys.sort_by do |attribute|
attribute.name.to_s
end
first = attributes.collect do |key|
engine.quote_column_name(key.name)
end.join(', ')
second = attributes.collect do |key|
key.format(record[key])
end.join(', ')
build_query "(#{first})", "VALUES (#{second})"
end
build_query \
"INSERT",
"INTO #{table_sql}",
insertion_attributes_values_sql,
("RETURNING #{engine.quote_column_name(primary_key)}" if include_returning && compiler.supports_insert_with_returning?)
end
def supports_insert_with_returning?
false
end
def update_sql
build_query \
"UPDATE #{table_sql} SET",
assignment_sql,
build_update_conditions_sql
end
protected
def method_missing(method, *args)
if block_given?
relation.send(method, *args) { |*block_args| yield(*block_args) }
else
relation.send(method, *args)
end
end
def build_query(*parts)
parts.compact.join(" ")
end
def assignment_sql
if assignments.respond_to?(:collect)
attributes = assignments.keys.sort_by do |attribute|
attribute.name.to_s
end
attributes.map do |attribute|
value = assignments[attribute]
"#{engine.quote_column_name(attribute.name)} = #{attribute.format(value)}"
end.join(", ")
else
assignments.value
end
end
def build_update_conditions_sql
conditions = ""
conditions << " WHERE #{wheres.collect(&:to_sql).join(' AND ')}" unless wheres.blank?
conditions << " ORDER BY #{order_clauses.join(', ')}" unless orders.blank?
unless taken.blank?
conditions = limited_update_conditions(conditions, taken)
end
conditions
end
def limited_update_conditions(conditions, taken)
conditions << " LIMIT #{taken}"
quoted_primary_key = engine.quote_column_name(primary_key)
"WHERE #{quoted_primary_key} IN (SELECT #{quoted_primary_key} FROM #{engine.connection.quote_table_name table.name} #{conditions})"
end
end
end
end