如何通过Ecto Multi从先前插入的表键中检索ID [英] How to retrieve id from previous inserted table key by Ecto Multi

问题描述

我想通过Ecto Multi从先前插入的表主键中检索ID.

I would like to retrieve id from previous inserted table primary key by Ecto Multi.

首先，我将插入到主表中.那么B明细表需要A.id.我尝试了以下代码.

At first, I insert to A main table. then B details table needs A.id. I tried following code.

Multi.new()
  |> Multi.insert(:insert, main)
  |> Multi.insert_all(:insert_all, B, details)
  |> Repo.transaction()

但是我不知道如何检索插入表B的A.id.我该怎么办?

However I have no idea how to retrieve A.id for insert table B. What I should do for it?

推荐答案

您可以执行以下示例，创建一个新的 User 记录和一个新的 Email 记录.(其中 email 记录通过 user_id 外键与父 user 记录相关联).

You can do something like the following example which creates a new User record and a new Email record (where the email record is associated to the parent user record via a user_id foreign key).

alias Ecto.Multi

user = get_user_params_from_form() # <-- or where-ever you are getting data
email = get_email_params_from_form()

Multi.new()
    |> Multi.insert(:user, User.changeset(%User{}, user))
    |> Multi.insert(
      :email,
      # Capture the id from the previous operation
      fn %{
           user: %User{
             id: user_id
           }
         } ->
        Email.changeset(%Email{user_id: user_id}, email)
      end
    )

我认为这证明了您描述的关系类型.希望对您有帮助！

I think this demonstrates the type of relationship you described. Hope it helps!

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