[Ruby on Rails] Individual display of error messages

Target

Development environment

ruby 2.5.7 Rails 5.2.4.3 OS: macOS Catalina

Premise

• If you select ▶ ◯◯, explanations will be displayed. I hope you can refer to it if you are not sure.

-Build login environment with devise

• If there are few descriptions, I think that it is an effective means, As the number increases, the number of descriptions will increase considerably, so I hope you can see it for reference.

edit view

In the initial state, it is described as follows.

erb:app/views/users/registrations/new.html.erb

<h2>Sign up</h2>

<%= form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f| %>
  <%= render "users/shared/error_messages", resource: resource %>

 　<div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name, autofocus: true, autocomplete: "name" %>
  </div>

  <div class="field">
    <%= f.label :email %><br />
    <%= f.email_field :email, autofocus: true, autocomplete: "email" %>
  </div>

  <div class="field">
    <%= f.label :password %>
    <% if @minimum_password_length %>
    <em>(<%= @minimum_password_length %> characters minimum)</em>
    <% end %><br />
    <%= f.password_field :password, autocomplete: "new-password" %>
  </div>

  <div class="field">
    <%= f.label :password_confirmation %><br />
    <%= f.password_field :password_confirmation, autocomplete: "new-password" %>
  </div>

  <div class="actions">
    <%= f.submit "Sign up" %>
  </div>
<% end %>

<%= render "users/shared/links" %>

Make edits to the above.

erb:app/views/users/registrations/new.html.erb

<h2>Sign up</h2>

<%= form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f| %>
  <% if @user.errors.any? %>
  <% end %>

  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name, autofocus: true, autocomplete: "name" %>
    <% if @user.errors.include?(:name) %>
      <p style="color: red;"><%= @user.errors.full_messages_for(:name).first %>
    <% end %>
  </div>

  <div class="field">
    <%= f.label :email %><br />
    <%= f.email_field :email, autofocus: true, autocomplete: "email" %>
    <% if @user.errors.include?(:email) %>
      <p style="color: red;"><%= @user.errors.full_messages_for(:email).first %>
    <% end %>
  </div>

  <div class="field">
    <%= f.label :password %>
    <% if @minimum_password_length %>
    <em>(<%= @minimum_password_length %> characters minimum)</em>
    <% end %><br />
    <%= f.password_field :password, autocomplete: "new-password" %>
    <% if @user.errors.include?(:password) %>
      <p style="color: red;"><%= @user.errors.full_messages_for(:password).first %>
    <% end %>
  </div>

  <div class="field">
    <%= f.label :password_confirmation %><br />
    <%= f.password_field :password_confirmation, autocomplete: "new-password" %>
    <% if @user.errors.include?(:password_confirmation) %>
      <p style="color: red;"><%= @user.errors.full_messages_for(:password_confirmation).first %>
    <% end %>
  </div>

  <div class="actions">
    <%= f.submit "Sign up" %>
  </div>
<% end %>

<%= render "users/shared/links" %>

Supplement

python

(1) Delete the following description and add an if statement.@Check for user errors.
<%= form_for〜%>
<%= render "users/shared/error_messages", resource: resource %>
↓
<%= form_for〜%>
<% if @user.errors.any? %>
<% end %>

(2) Add the following column names under each field after editing.
<% if @user.errors.include?(:name) %>
  <p style="color: red;"><%= @user.errors.full_messages_for(:name).first %>
<% end %>

If you want to add validation and see more errors, If you add as below, it's OK. There are many types of validation, so please check it out. By the way, I have confirmed that the following validations are not blank.

app/models/user.rb

validates :name, presence: true