ECTO-验证关联模型的存在 [英] Ecto - validate presence of associated model

问题描述

如何验证Ecto中相关模型的存在?

How can one validate the presence of an associated model in Ecto ?

schema "foo" do
  has_many: bar, Bar

  timestamps
end

@required_fields ~w(bar) # invalid

有办法吗?并验证这些字段的最小/最大数量?

Is there a way to do so ? And validate a min/max number of these fields ?

推荐答案

还没有任何东西.但是您可以在changeset函数中自己运行这些验证:

There isn't anything yet. But you can run these validations yourself in your changeset function:

def changeset(model, params) do
  model
  |> cast(...)
  |> validate_bar_association()
end

def validate_bar_association(changeset) do
  bar = changeset.model.bar
  cond do
    bar == nil ->
      add_error changeset, :bar, "No bar"
    length(bar) < 5 ->
      changeset
    true ->
      add_error changeset, :bar, "waaaay too many"
  end
end

我们确实想使嵌套关联更好，但是优先级列表中还有其他更高的项. :)

We do want to make nested associations better but there are other items higher up on our priority list. :)

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