我实施它的方式似乎不是。
在 data_mapper 术语中 - 我有一个加入资源条目,它加入了 Driver、Team 和 Season
我有一个加入 Track and Season 的加入资源 Race
我有一个加入 Entry 和 Race 的加入资源放置。
当我尝试做类似“向我展示某个特定参赛者参加的所有比赛时,例如
@entry_a.races.all
我收到这个错误
DataObjects::SyntaxError: no such column: INNER (code: 1, sql state: , query: SELECT "races"."track_id", "races"."season _id", "races"."race_no" FROM "races" INNER JOIN "配售" ON INNER JOIN "entrys" ON "配售"."entry_team_id" = "entries"."team_id" AND "配售"."entry_driver_id" = "entries"."driver_id" WHERE ("配售". "entry_team_id" = 'FER' AND " placements"."entry_driver_id" = 'MAS') GROUP BY "races"."track_id", "races"."season_id", "races"."race_no" ORDER BY "races" ."track_id", "races"."season_id", uri:sqlite3:C/devProjects/formula1../spec/resources/test.db?scheme=sqlite3&user=&pas Sword=&host=C&port=&query=&fragment=&adapter=sqlite3&path=/devProjects/formula1../spec/resources/test。 D b)
很容易看到这里发生了什么,由 .all 方法包装的查询并不期望在连接时连接。
我设法通过编写一些自定义 sql 来解决这个问题。虽然不理想,但它确实可以完成这项工作。不过,这似乎不是红宝石方式。也许我的数据库架构很烂?
这是我的模型(对代码转储感到抱歉。我被一个 SO 因为我没有引用完整的代码而决定对我投反对票的同事烧死了)
require "rubygems"
require "sqlite3"
require "data_mapper"
require "bigdecimal"
#note that Dir.pwd refers to the location of the file that calls
if ENV["run_mode"] == "prod"
DataMapper::setup(:default, "sqlite3://#{Dir.pwd}/data/prod.db")
else
DataMapper::setup(:default, "sqlite3://#{Dir.pwd}../spec/resources/test.db")
end
class Entry
include DataMapper::Resource
belongs_to :team, :key => true
belongs_to :driver, :key => true
belongs_to :season, :key => true
has n, :placings
has n, :races, :through => :placings
def find_races
return repository.adapter.select('SELECT races.track_id, races.season_id, races.race_no FROM races INNER JOIN placings ON races.track_id = placings.race_track_id INNER JOIN entries ON placings.entry_driver_id = entries.driver_id WHERE (entries.team_id = ? AND entries.driver_id = ?)', self[:team_id], self[:driver_id])
end
end
class Track
include DataMapper::Resource
property :id, String, :key => true
has n, :races
end
class Race
include DataMapper::Resource
property :race_no, Integer
belongs_to :track, :key => true
belongs_to :season, :key => true
has n, :placings
has n, :entries, :through => :placings
end
class Placing
include DataMapper::Resource
property :id, Serial #put this in because dm was complaining that foreign keys from entry object were not unique
belongs_to :race
belongs_to :entry
end
class Season
include DataMapper::Resource
property :id, Integer, :key => true
has n, :races
has n, :entries
end
class Driver
include DataMapper::Resource
property :id, String, :key => true
property :team, String
property :ptd, Integer
property :races, Integer
property :grid, Object
property :race, Object
property :cumulativePoints, Object #the number of points accumulated at a particular point in the season
property :hcScore, Integer
property :domScore, Integer
property :nation, String
property :wins, Integer
property :podiums, Integer
has n, :entries
has n, :teams, :through => :entries
end
class Team
include DataMapper::Resource
property :id, String, :key => true
property :name, String
property :ptd, Integer
property :domScore, Integer
property :nation, String
has n, :entries
has n, :drivers, :through => :entries
def initialize(team_id)
self[:id] = team_id
self.save!
end
def add_driver(driver_id)
@driver = Driver.create(:id => driver_id)
Entry.create(:driver => (Driver.get driver_id), :team => self, :season => Season.last)
return @driver
end
end
class Nation
include DataMapper::Resource
property :id, String, :key => true
property :ptd, Integer
# could possibly have the drivers, teams and engines here as well
end
if ENV["run_mode"] == "test"
DataMapper.finalize.auto_migrate!
else
DataMapper.finalize.auto_upgrade!
end