# [Rails4][pagination]自製簡易分頁功能

###### tags: `Rails4`,`pagination`

## partials
_pagination.html.erb

<%
=begin
params:

controller
action
id(optional)
extra_params(optional)
page_index
page_count

=end
%>

<!-- pagination -->

<%

  extra_params= extra_params || {}
  id= id || nil

  path= Proc.new{|page_index| url_for(
    {
    controller: controller,
    action: action, 
    id: id,
    page_index: page_index
    }.merge(extra_params)
    )}
%>

<nav aria-label="..." class="mt-4">
  <ul class="pagination">
    <li class="<%= page_index.to_i<=1 ? 'page-item disabled' : 'page-item' %>">
      <%= link_to  "previous", path.call(page_index.to_i-1), class:"page-link" %>

      <!-- <a class="page-link" href="#" tabindex="-1" aria-disabled="true">Previous</a> -->
    </li>

    <% [*1..page_count].each do |i| %>
      <li class="<%= i.to_i == page_index.to_i ? 'page-item active' : 'page-item' %>">
        <%= link_to  i, path.call(i), class:"page-link" %>
      </li>
    
    <% end %>

    
    <li class="<%= page_index.to_i>=page_count ? 'page-item disabled' : 'page-item' %>">
    <%= link_to  "next", path.call(page_index.to_i+1), class:"page-link" %>

    </li>
  </ul>
</nav>
<!-- /pagination -->

## 使用方式:

### 在要引用的view中加入以下程式碼:

<%= render partial:"path/to/partials",locals:{
  controller:"controller_name",
  action:"action_name",
  id: @cat.id,
  page_index: @page_index,
  page_count: @page_count
  } %

### 在controller action加入以下程式碼
(以product為例):

@total = Product.count
@item_per_page = 5
@page_count = (@total.to_f / @item_per_page.to_f).ceil
@page_index=params[:page_index] ? params[:page_index] : 1
@products=Product.offset( (@page_index.to_i-1)*@item_per_page ).limit(@item_per_page)