我正在使用Rails 4.1和我的模型:
Client has_many TicketLists
TicketList has many projects
现在我正在尝试在客户端模型中使用预先加载,例如:
class Client < ActiveRecord::Base
def ticket_lists_with_project_id(project_id)
ticket_lists.includes(:projects).where("projects.id = ?", project_id)
end
end
当我这样做时:
Client.find(2).ticket_lists_with_project_id(1)
Client Load (1.7ms) SELECT "clients".* FROM "clients" WHERE "clients"."is_destroyed" = 'f' AND "clients"."is_closed" = 'f' AND "clients"."id" = $1 LIMIT 1 [["id", 2]]
PG::UndefinedTable: ERROR: missing FROM-clause entry for table "projects"
LINE 1: ...d" = 'f' AND "ticket_lists"."client_id" = $1 AND (projects.i...
^
: SELECT "ticket_lists".* FROM "ticket_lists" WHERE "ticket_lists"."is_destroyed" = 'f' AND "ticket_lists"."client_id" = $1 AND (projects.id = 1)
ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR: missing FROM-clause entry for table "projects"
LINE 1: ...d" = 'f' AND "ticket_lists"."client_id" = $1 AND (projects.i...
答案 0 :(得分:9)
尝试以下方法:
class Client < ActiveRecord::Base
def ticket_lists_with_project_id(project_id)
ticket_lists.includes(:projects)
.where("projects.id = ?", project_id)
.references(:projects)
end
end
它会起作用。如果您想要add conditions加入所包含的模型,则必须明确引用它们。另外 note includes
使用关联名称,而references
需要实际的表名。
答案 1 :(得分:3)
而不是:
ticket_lists.includes(:projects).where("projects.id = ?", project_id)
这样做:
ticket_lists.joins(:projects).where("projects.id = ?", project_id)
由于你使用的是Rails 4,你可以让它看起来更可爱:
ticket_lists.joins(:projects).where(projects: {id: project_id})
答案 2 :(得分:1)
这可能会对您有所帮助:
Client.includes(:ticket_lists => :projects).where("clients.id = ? ", 2)
OR
class Client < ActiveRecord::Base
def ticket_lists_with_project_id(project_id)
Client.includes(:ticket_lists => :projects).where("projects.id = ?", project_id)
end
end