擅长:python、mysql、java
<p>一个简单的修复方法是在您的<code>Item</code>类中定义<code>keys()</code>方法:</p>
<pre><code>class MyItem(Item):
foo = Field()
bar = Field()
gar = Field()
cha = Field()
def keys(self):
# in your preferred order
return ['cha', 'gar','bar','foo']
</code></pre>