带有has_many的嵌套表单，其中包含现有记录

Question

在我的应用程序中，我有客户和联系人。客户可以有多个联系人，联系人可以有多个客户。它们通过CustomerContact表相关联。问题是，基于他们的电子邮件地址，数据库只能有一个唯一的联系人。

那是什么，我想创建一个表单，用户可以在其中输入客户信息和他们想要的联系人数量。我使用cocoon gem实现了这一点。现在的问题是，没有“选择现有联系人”，只有文本字段，其思想是，当提交表单时，系统可以通过现有的电子邮件地址查看系统中是否已经存在联系人，并且不仅将客户分配给该联系人，还可以更新现有的联系人信息。如果是新联系人，则只需在数据库中插入一个新联系人并将该联系人分配给客户即可。

很明显，这完全超出了正常的处理方式。你通常会进行某种查找，然后选择一个现有的联系人，但这不是老板想要的。

这是我遇到的问题

当我为数据库中已存在的联系人输入电子邮件地址时，Rails总是抛出错误“联系人电子邮件已经被占用”。“没问题，我想”，对于现有的联系人，我将在数据库中查找，并通过操作控制器中的params来创建联系人的id属性。所以我写了下面的代码：

# convert the params to a Hash so we can manuipulate them
myparams = customer_params.to_h

# if we have contacts we want to assign to the customer
if myparams['contacts_attributes']
  # loop through each contact they entered
  myparams['contacts_attributes'].each do |k,v|
    # see if the contact exists in the database and isn't being destroyed
    if Contact.exists?(email: v['email']) && v['_destroy'] != '1'
      # grab the contact information
      contact = Contact.where(email: v['email']).first
      # just a double check that we got the contact from the database
      if contact
        # create an id attribute for the contact
        myparams['contacts_attributes'][k]['id'] = contact.id
      end
    end
  end
end

“太美了！”或者我是这样想的。当我尝试保存联系人时，遇到以下错误：

Couldn't find Contact with ID=117 for Customer with ID=

显然，当我将参数传递给Customer#new方法时，Rails正在对CustomerContact表执行查找，试图访问Contacts表，这样它就可以获得联系人的信息。但是，由于这是一个新客户，因此该关联尚未建立，因为该客户尚未创建。

好的..。所以我有了这个想法

如果我从contact_attributes中删除现有联系人并直接创建customer_contacts关联会怎么样！因此，在myparams['customer_contacts_attributes'] = []发挥作用的地方：

# convert the params to a Hash so we can manuipulate them
myparams = customer_params.to_h
# so we can create a record on the customer_contacts association
# directly if the contact already exits
myparams['customer_contacts_attributes'] = []    

# if we have contacts we want to assign to the customer
if myparams['contacts_attributes']
  # loop through each contact they entered
  myparams['contacts_attributes'].each do |k,v|
    # see if the contact exists in the database and isn't being destroyed
    if Contact.exists?(email: v['email']) && v['_destroy'] != '1'
      # grab the contact information
      contact = Contact.where(email: v['email']).first
      # just a double check that we got the contact from the database
      if contact
        # removed the contact
        myparams['contacts_attributes'].delete(k)
        # create the `customer_contact` association directly
        myparams['customer_contacts_attributes'].push({'user_id': contact.id})
      end
    end
  end
end

还有..。成功了！嗯，一些什么。保存客户，分配数据库中已存在的联系人，并创建和分配新的联系人...那么问题出在哪里呢？好吧..。如果由于任何原因验证失败，并且页面被重新绘制，则用户输入的现有联系人将从表单中消失。

我请求帮助

所以我有一些工作，但我真的需要帮助。我需要它，以便如果验证失败，联系人显示在表单中。而且，很明显这不是最好的方法。我希望有人以前在rails中做过这样的事情，并且有更好的方法来实现它。

我的关联设置如下：

class CustomerContact < ApplicationRecord
  belongs_to :customer
  belongs_to :contact
end

class Customer < ApplicationRecord
  has_many :customer_contacts
  has_many :contacts, through: :customer_contacts

  accepts_nested_attributes_for :customer_contacts
  accepts_nested_attributes_for :contacts, allow_destroy: true
end

class Contact < ApplicationRecord
  has_many :customer_contacts
  has_many :customers, through: :customer_contacts
end

contact部分的设置如下所示，请注意，我在new和edit操作中都使用了它：

<table class="table table-striped">
  <thead>
  <tr>
    <th>Name</th>
    <th>Email</th>
    <th>Phone</th>
    <th>Department</th>
    <th>Manager</th>
    <th>
      <%= link_to_add_association f, :contacts, class: 'btn btn-primary', partial: 'contact_fields', data: {
          association_insertion_node: '.contact_fields', association_insertion_method: :append
      } do %>
          <i class="fas fa-plus"></i>
      <% end %>
    </th>
  </tr>
  </thead>
  <tbody class="contact_fields">
  <%= f.fields_for :contacts do |contact| %>
      <%= render 'projects/contact_fields', f: contact %>
  <% end %>
  </tbody>
</table>

contact_fields partial如下：

<tr class="nested-fields">
  <td>
    <%= f.text_field :fullname, class: 'form-control invoke-contacts-search contact-fullname' %>
  </td>
  <td>
    <%= f.text_field :email, class: 'form-control invoke-contacts-search contact-email' %>
  </td>
  <td>
    <%= f.text_field :phone, class: 'form-control contact-phone' %>
  </td>
  <td>
    <%= f.text_field :department, class: 'form-control contact-department' %>
  </td>
  <td>
    <%= f.text_field :manager, class: 'form-control contact-manager' %>
  </td>
  <td>
    <%= link_to_remove_association  f, class: 'btn btn-danger' do %>
        <i class="fas fa-trash-alt"></i>
    <% end %>
  </td>
</tr>

下面是控制器new和create操作

def new
  @customer = Customer.new
  4.times { @customer.contacts.build }
end

def create

# convert the params to a Hash so we can manuipulate them
myparams = customer_params.to_h
# so we can create a record on the customer_contacts association
# directly if the contact already exits
myparams['customer_contacts_attributes'] = []    

# if we have contacts we want to assign to the customer
if myparams['contacts_attributes']
  # loop through each contact they entered
  myparams['contacts_attributes'].each do |k,v|
    # see if the contact exists in the database and isn't being destroyed
    if Contact.exists?(email: v['email']) && v['_destroy'] != '1'
      # grab the contact information
      contact = Contact.where(email: v['email']).first
      # just a double check that we got the contact from the database
      if contact
        # removed the contact
        myparams['contacts_attributes'].delete(k)
        # create the `customer_contact` association directly
        myparams['customer_contacts_attributes'].push({'user_id': contact.id})
      end
    end
  end
end

  @customer = Customers.new(myparams)

  respond_to do |format|
    if @customer.save
      format.html { redirect_to edit_customer_path(@customer), success: 'Customer was successfully created.' }
    else
      format.html { render :new }
    end
  end
end

以下是控制器的编辑和更新操作

def edit
  @customer = Customer.find(params[:id])
end

def update
  myparams = customer_params.to_h

  if myparams['contacts_attributes']
    myparams['contacts_attributes'].each do |k,v|
      if Contacts.exists?(email: v['email']) && v['_destroy'] != '1'
        contact = Contact.where(email: v['email']).first
        if contact
          myparams['contacts_attributes'][k]['id'] = contact.id
          CustomerContact.find_or_create_by(project_id: @customer.id, user_id: contact.id)
        end
      end
    end
  end

  @customer.assign_attributes(myparams)

  respond_to do |format|
    if @customer.save
      format.html { redirect_to edit_customer_path(@customer), success: 'Customer was successfully updated.' }
    else
      format.html { render :edit }
    end
  end
end

Answer 1

所以我终于让它工作了，但为了让它工作，我基本上必须重新实现嵌套属性为您做的所有事情。它不是很漂亮，但它工作得很好。

还有..。查看this post，看看我是如何在模板中收集联系人的

  def update

    myparams = customer_params.to_h
    contacts_valid = true
    @customer.assign_attributes(myparams)
    customer_valid = @customer.valid?
    @contacts = []
    contacts_to_delete = []

    cparams = contact_params.to_h
    cparams['contacts'].each do |k, v|
      if v['id'].to_i > 0
        if v['_destroy'].to_i == 1
          contacts_to_delete << v['id'].to_i
        else
          contact = Contact.find(v['id'])
          contact.assign_attributes(v.except('_destroy', 'id'))
        end
      else
        if (!v['name'].blank? || !v['email'].blank?) && v['_destroy'].to_i != 1
          unless v['email'].blank?
            contact = Contact.where(email: v['email']).first
          end
          if contact
            contact.assign_attributes(v.except('_destroy', 'id'))
          else
            contact = Contact.new(v.except('_destroy', 'id'))
          end
        end
      end

      if contact
        unless contact.valid?
          contacts_valid = false
          # This adds the errors from the contact to the customer object
          contact.errors.full_messages.each do |m|
            @customer.errors.add(:base, m)
          end
        end
        @contacts << contact
      end
    end

    respond_to do |format|
      if customer_valid && contacts_valid
        @customer.save!
        @contacts.each do |c|
          c.save!
          CustomerContact.find_or_create_by(customer_id: @customer.id, contact_id: c.id)
        end
        CustomerContact.where(customer_id: @customer.id, contact_id: contacts_to_delete).destroy_all

        format.html { redirect_to edit_customer_path(@customer), success: 'Customer was successfully updated.' }
        format.json { render :show, status: :ok, location: @customer }
      else
        format.html {
          (6 - @contacts.count).times { @contacts << @customer.contacts.build }
          render :edit
        }
        format.json { render json: @customer.errors, status: :unprocessable_entity }
      end
    end

  end

  def customer_params
    params.require(:customer).permit(:company, :name, :line1, :line2, :city, :state, :zipcode, :country, :webaddress, :status,
                                     contacts_attributes: [:fullname, :phone, :email, :department, :manager, :id, :_destroy],
                                     notes_attributes: [:note]
    )
  end

  def contact_params
    params.permit(contacts: [:fullname, :email, :phone, :department, :manager, :id, :_destroy])
  end