在<代码>()中,你可以从你的结构中提取这些数值,并将这些数值储存在册,然后这些数值可用于填入<编码>。 在用户对表格进行改动后,将打电话到handle_event(>,handle_event()将接受表格中所用的数值。

In addition, inside mount() you can save your original struct in the socket, then in handle_event() you will be able to access any values from the struct that you need. After the user hits Submit, handle_event() will receive the final values entered into the form, which you can use to update the original struct.

例如:

#=========  Your struct code =======

defmodule MyApp.MyStruct do
  defstruct some_integer: 3,
            some_string: "",
            some_bool: true
end

defmodule MyApp.Context do
  alias MyApp.MyStruct

  def current_struct() do
    %MyStruct{}
  end
end

#================================

defmodule DemoWeb.DemoLive do
  use DemoWeb, :live_view

  def mount(_params, _session, socket) do
    orig_struct = MyApp.Context.current_struct()
    o_int = orig_struct.some_integer
    o_string = orig_struct.some_string
    o_bool = orig_struct.some_bool

    initial_form_data = %{
      "input_int" => o_int,
      "input_string" => o_string,
      "input_bool" => o_bool
    }

    socket = assign(socket,
        my_struct: orig_struct,
        current_int: o_int,
        current_string: o_string,
        current_bool: o_bool,
        my_form: to_form(initial_form_data)
      )

    {:ok, socket}
  end

  def render(assigns) do

    # When you write:
    #
    # <.form for={@my_form} ... >
    #   <.input  field={@my_form[:input_int] } ... />
    #
    # that creates an input element with the type atribute set to "text",
    # the name and id attributes set to "input_int", and the value
    # attribute set to the value corresponding to the "input_int" key in the form data
    # given to to_form().  If there s no key for "input_int" in the form data, then there
    # won t be a value attribute--unless you explicitly set the value attribute.  Explicitly
    # setting the value attribute takes precedence over any form data given to to_form().
    #

    ~H"""
    <div>
      <%= "current integer: #{@current_int}, current string: #{@current_string},
           current bool: #{@current_bool}"  %>
    </div>
    <div>
    <%= "original integer: #{@my_struct.some_integer}, original string: #{@my_struct.some_string},
           original bool: #{@my_struct.some_bool}"  %>
    </div>
    <div>-------</div>
    <div>-------</div>


    <.form for={@my_form} phx-change="changed" phx-submit="save">
      <.input label="Some integer:"
              field={@my_form[:input_int] } 
              value={@current_int}
      />
      <.input label="Some string:"
              field={@my_form[:input_string]} 
              value={@current_string}
      />
      <.input label="Some bool:"
              field={@my_form[:input_bool]}
              value={@current_bool}
      />
      <.button>Submit</.button>
    </.form>
    """
  end

  def handle_event("changed",
                   %{"input_int" => entered_int,
                     "input_string" => entered_string,
                     "input_bool" => entered_bool
                    },
                  socket) do

    #Do something with entered_int, entered_string, entered_bool, e.g. change
    #the values that the <div> uses:
    socket = assign(socket,
                    current_int: entered_int,
                    current_string: entered_string,
                    current_bool: entered_bool
              )

    {:noreply, socket}
  end

  def handle_event("save",
                   %{"input_int" => entered_int,
                     "input_string" => entered_string,
                     "input_bool" => entered_bool
                    },
                   socket) do

    start_struct = socket.assigns.my_struct
    updated_struct = %{start_struct | some_integer: entered_int,
                                      some_string: entered_string,
                                      some_bool: entered_bool}
    #Do something with updated_struct, e.g.:
    IO.inspect(updated_struct, label: "[ME]updated struct:")

    {:noreply, socket}
  end


end

这里是活语页面所看的例子:

 def handle_event("save",
                   %{"input_int" => entered_int,
                     "input_string" => entered_string,
                     "input_bool" => entered_bool
                    },
                   socket) do

iex(2)> function_argument = %{"a" => 10, "b" => 20}
%{"a" => 10, "b" => 20}

iex(3)> %{"a" => a_val} = function_argument
%{"a" => 10, "b" => 20}

iex(4)> a_val
10

iex(5)> %{"b" => b_val, "a" => a_val} = function_argument
%{"a" => 10, "b" => 20}

iex(6)> b_val
20

iex(7)> a_val
10

 def handle_event("save", payload, socket) do

   %{"input_int" => entered_int,
     "input_string" => entered_string,
     "input_bool" => entered_bool} = payload
               

updated_struct = %{start_struct | some_integer: entered_int,
                                  some_string: entered_string,
                                  some_bool: entered_bool}

利用special syntax,用于更新地图或结构(如用于清单的Syntax)。 特别辛迪加确保这些钥匙已经列入地图,因此,错失行为不会给地图增添新的钥匙。

Watch the output in a terminal window, and you ll be able to see what happens when you change an input field or hit the Submit button.

When I try to use input_value(), then I always get nil, even if inspect(form) shows that both some_integer and some_bool have the values that I expect them to have.