Elixir 表联接
EXTO文档展示了如何连接两个表(A您可以在树状结构中预加载关联,然后根据需要映射结果Elixir 表联接,elixir,ecto,Elixir,Ecto,EXTO文档展示了如何连接两个表(A您可以在树状结构中预加载关联,然后根据需要映射结果 > subquery = App.Post |> preload(:comments) #Ecto.Query<from p in App.Post, preload: [:comments]> > query = App.User |> preload(posts: ^subquery) #Ecto.Query<from u in App.User, prelo
> subquery = App.Post |> preload(:comments)
#Ecto.Query<from p in App.Post, preload: [:comments]>
> query = App.User |> preload(posts: ^subquery)
#Ecto.Query<from u in App.User,
preload: [posts: #Ecto.Query<from p in App.Post, preload: [:comments]>]>
> Repo.all(query)
[
%App.User{...},
%App.User{...},
%App.User{
...,
posts: [
%App.Post{...},
%App.Post{...},
%App.Post{
...,
comments: [
%App.Comment{...},
%App.Comment{...},
%App.Comment{...}
]
}
]
}
]
>subquery=App.Post |>预加载(:注释)
#异位查询
>query=App.User |>预加载(帖子:^子查询)
#异位查询
>全部回购(查询)
[
%App.User{…},
%App.User{…},
%应用程序用户{
...,
职位:[
%App.Post{…},
%App.Post{…},
%App.Post{
...,
评论:[
%App.Comment{…},
%App.Comment{…},
%App.Comment{…}
]
}
]
}
]
> subquery = App.Post |> preload(:comments)
#Ecto.Query<from p in App.Post, preload: [:comments]>
> query = App.User |> preload(posts: ^subquery)
#Ecto.Query<from u in App.User,
preload: [posts: #Ecto.Query<from p in App.Post, preload: [:comments]>]>
> Repo.all(query)
[
%App.User{...},
%App.User{...},
%App.User{
...,
posts: [
%App.Post{...},
%App.Post{...},
%App.Post{
...,
comments: [
%App.Comment{...},
%App.Comment{...},
%App.Comment{...}
]
}
]
}
]