获取哈希键/值或默认值时，无论是键/值或整个哈希可能不存在

我是新来的Ruby和想如果这是关键，其中无论是哈希键进行访问哈希的最佳方式不存在或整个哈希不存在。获取哈希键/值或默认值时，无论是键/值或整个哈希可能不存在

此代码运行在Rails的部分，也许有或无PARAMATERS被调用。

可以将此代码加以改进，或者这是最好的技术

title = (defined?(locals) && locals[:title]) || 'Sponsored Links'

调用部分上2个不同视图

视图1

<%=render 'advertisement/advert_panels', locals: { site_section: 'Public', ad_count: 3, is_hr: false } %>

视图2

<%= render partial: "advertisement/advert_panels" %>

福部分

<% 
    # ************************************************************************ 
    # IS THIS the best way to access locals[KEY] || default value 
    # ************************************************************************ 
    title = (defined?(locals) && locals[:title]) || 'Sponsored Links' 
    site_section = (defined?(locals) && locals[:site_section]) || :signed_in 
    ad_count = (defined?(locals) && locals[:ad_count]) || 3 
    css_inner_container = (defined?(locals) && locals[:css_inner_container]) || 'margin-top-5 margin-bottom-5' 
    is_hr = (site_section == :signed_in) 
%> 

<% @adverts = Advertisement.get_ads_by_location(site_section, location_id, 0, ad_count) %> 

<% if @adverts.length > 0 %> 

<div class="row-fluid"> 
    <h3 class="darkBlue center"><%=title%></h3> 
    <% if is_hr %><hr /><%end%> 

    <% @adverts.each do |item| %> 

    <div class='<%= css_inner_container %>'> 
    <a href="<%= item.target_url %>" target="<%= item.name.delete(' ')%>"> 
      <img src="<%= item.image_url %>" title="<%=item.name%>" /> 
     </a> 
    </div> 

    <% end %> 
</div> 

<% end %>

来源

2014-12-04 David Cruwys

LL代码可以使用local_assigns对象来测试，如果事情已定。参考here

<% 
    title = (local_assigns.has_key?(:title) && title) || 'Sponsored Links' 
    site_section = (local_assigns.has_key?(:site_section) && site_section) || :signed_in 
    ad_count = (local_assigns.has_key?(:ad_count) && ad_count) || 3 
    css_inner_container = (local_assigns.has_key?(:css_inner_container) && css_inner_container) || 'margin-top-5 margin-bottom-5' 
    is_hr = (site_section == :signed_in) 
%>

来源

2014-12-04 02:28:52 rdubya

获取哈希键/值或默认值时，无论是键/值或整个哈希可能不存在

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