Rails:无法将图像解析为URL:to_model委托给附件，但是附件为nil Rails 5.2

问题描述

我的格式如下:

<%= form_with(model: user, local: true) do |form| %>
  <% if user.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(user.errors.count, "error") %> prohibited this user from being saved:</h2>

      <ul>
      <% user.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= form.file_field :avatar %>
  </div>

  <div class="actions">
    <%= form.submit %>
  </div>
<% end %>

在我的edit页面上正在调用它:

It is being called on my edit page:

<h1>Upload Avatar</h1>
  <%= image_tag(@user.avatar) %>
  <%= render 'form', user: @user %>
<hr>

我收到标题错误，但是我不确定为什么头像没有附加到user模型上.我已经完成了active_storage的所有要求.

I get the error in the title but I am not sure why the avatar is not being attachd to the user model. I have all the requirements done for active_storage.

has_one_attached :avatar.

在user controller中:

  def identity_params
    params.permit(:email_confirmation, :password, :password_confirmation, :avatar).to_h.symbolize_keys.tap do |params|
      params[:email] = params[:email_confirmation]
    end 
  end 

我也有所有必要的迁移.我是否缺少实际的头像附加逻辑?

Also I have all the necessary migrations. Am I missing the actual avatar attaching logic?

推荐答案

您会收到错误消息无法将图像解析为URL:to_model委托给附件，但附件为零" 您试图在视图中显示不存在的附件:

You can get the error message "Can't resolve image into URL: to_model delegated to attachment, but attachment is nil" if you are trying to show in your view an attachment that does not exist:

<%= image_tag(@user.avatar) %>

为避免错误，您应该执行以下操作:

to avoid error you should do this:

<%= image_tag(@user.avatar) if @user.avatar.attached? %>

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