ecto模型参数未验证？

Question

可能是我遗漏了什么，但它觉得这应该是一个无效的记录：

pry(1)> project_params
%{"name" => ""}
pry(2)> changeset
%Ecto.Changeset{action: nil, changes: %{name: ""}, constraints: [], errors: [],
 filters: %{},
 model: %Elix.Project{__meta__: #Ecto.Schema.Metadata<:built>, id: nil,
  inserted_at: nil, name: nil, updated_at: nil,
  user: #Ecto.Association.NotLoaded<association :user is not loaded>,
  user_id: 2}, optional: [], opts: [], params: %{"name" => ""}, prepare: [],
 repo: nil, required: [:name, :user_id],
 types: %{id: :id, inserted_at: Ecto.DateTime, name: :string,
   updated_at: Ecto.DateTime, user_id: :id}, valid?: true, validations: []}
pry(3)> changeset.valid?
true

下面是我对模型的定义：

项目

defmodule Elix.Project do
  use Elix.Web, :model

  schema "projects" do
    field :name, :string
    belongs_to :user, Elix.User

    timestamps
  end

  @required_fields ~w(name user_id)
  @optional_fields ~w()

  @doc """
  Creates a changeset based on the `model` and `params`.

  If no params are provided, an invalid changeset is returned
  with no validation performed.
  """
  def changeset(model, params \\ :empty) do
    model
    |> cast(params, @required_fields, @optional_fields)
  end
end

用户

defmodule Elix.User do
  use Elix.Web, :model

  schema "users" do
    field :email, :string
    field :password, :string, virtual: true
    field :crypted_password, :string
    has_many :projects, Elix.Project

    timestamps
  end

  @required_fields ~w(email password)
  @optional_fields ~w()

  @doc """
  Creates a changeset based on the `model` and `params`.

  If no params are provided, an invalid changeset is returned
  with no validation performed.
  """
  def changeset(model, params \\ :empty) do
    model
    |> cast(params, @required_fields, @optional_fields)
    |> unique_constraint(:email)
    |> validate_format(:email, ~r/@/)
    |> validate_length(:password, min: 5)
  end
end

这是控制器创建操作的代码：

def create(conn, %{"project" => project_params}) do
    changeset =
      Ecto.build_assoc(conn.assigns.current_user, :projects) |>
      Project.changeset(project_params)
IEx.pry
    case Repo.insert(changeset) do
      {:ok, project} ->
        conn
        |> put_flash(:info, "Project #{project.name} created succesfully")
        |> redirect(to: project_path(conn, :index))
      {:error, changeset} ->
        render(conn, "new.html", project: changeset)
    end
  end

我提交表单时没有故意输入任何内容，这样我就可以测试表单显示错误。我在这里错过了什么？

Answer 1

只有当changeset.valid?的值为nil时，name才会是nil。因为在您的情况下，name的值是空字符串，所以变更集将是有效的。

处理以值形式传递空字符串的表单的最佳位置是在控制器中添加scrub_params插件，如下所示：

plug :scrub_params, "project" when action in [:create, :update]

有关文档的更多信息，请查看scrub_params。