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database - 创建phoenix表单并提交时出错

问题描述

我是凤凰和长生不老药的新手。尝试创建表单以将 1 个句子提交到数据库中，单击提交表单时出现错误。顺便提一句。我正在学习一些课程，我很困惑。有代码 Opa_Controller.ex

 defmodule Test.OpaController do
   use Test.Web, :controller
     alias Test.Opa

    def new(conn,_params) do
     struct = %Test.Opa{}
     params = %{}
     changeset = Test.Opa.changeset(struct,params)
     render conn, "sex.html", changeset: changeset
   end
   def create(conn,%{"naziv" => naziv}) do

     changeset = Opa.changeset(%Opa{}, naziv)
    case Repo.insert(changeset) do
      {:ok, post} -> IO.inspect(post)
       {:error, changeset} -> IO.inspect(changeset)
   end
   end
 end

测试.ex

 defmodule Test.Opa do
   use Test.Web, :model

   schema "opala" do
     field :naziv, :string
   end

   def changeset(struct, params \\ %{}) do
     struct
     |> cast(params, [:naziv])
     |> validate_required ([:naziv])
   end
 end

html文件

 <%= form_for @changeset, opa_path(@conn, :create), fn f -> %>
     <%= text_input f, :naziv, placeholder: "naziv" %>
     <%= submit "Save Topic" %>
 <% end %>

路由器.ex

     get "/", PageController, :index
     get "/opa/new", OpaController, :new
     get "/hello", HelloController, :index
     post "/opa", OpaController, :create

在终端我得到

     [debug] ** (Phoenix.ActionClauseError) could not find a matching      Test.OpaController.create clause
     to process request. This typically happens when there is a
     parameter mismatch but may also happen when any of the other
     action arguments do not match. The request parameters are:

       %{"_csrf_token" => "BDgWfgElRhRdSgoFBTo0BF4+P1YXNgAAtANQOf4Fi+GIlpej+Mt1eg==", "_utf8" => "✓", "opa" => %{"naziv" => "sa"}}

在浏览器中：https ://pastebin.com/A2Z3466D

标签： databaseelixirphoenix-framework

解决方案

create 操作需要一个顶级 map key "naziv"，从函数定义中可以看出：

def create(conn,%{"naziv" => naziv}) do

发送到控制器操作的参数（如错误消息中所示）是：

%{
  "_csrf_token" => "BDgWfgElRhRdSgoFBTo0BF4+P1YXNgAAtANQOf4Fi+GIlpej+Mt1eg==",
  "_utf8" => "✓",
  "opa" => %{"naziv" => "sa"}
}

如我们所见，"naziv"嵌套在顶级"opa"键下。

我们真正想要克服的是改变 create 函数中的模式匹配，以便它需要一个顶级"opa"键：

    def create(conn,%{"opa" => opa_params}) do
      changeset = Opa.changeset(%Opa{}, opa_params)
      case Repo.insert(changeset) do
        {:ok, post} -> IO.inspect(post)
        {:error, changeset} -> IO.inspect(changeset)
      end
    end

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