为了避免写十几次又长又丑的三进制，比如p_count = root.pool_count if hasattr(root, 'pool_count') else (-1)，我写了 GetThis(el, attr, err="") 函数。
如何获得将el 和attr 的值 连接到一个元素中的函数，而不是attr 作为文字？
test_data = ("""
<rsp stat="ok">
<group id="34427465497@N01" iconserver="1" iconfarm="1" lang="" ispoolmoderated="0" is_member="0" is_moderator="0" is_admin="0">
<name>GNEverybody</name>
<members>245</members>
<pool_count>133</pool_count>
<topic_count>106</topic_count>
<restrictions photos_ok="1" videos_ok="1" images_ok="1" screens_ok="1" art_ok="1" safe_ok="1" moderate_ok="0" restricted_ok="0" has_geo="0" />
</group>
</rsp>
""")
################
from lxml import etree
from lxml import objectify
################
def GetThis(el, attr, err=""):
if hasattr(el, attr):
return el.attr
else:
return err
################
Grp = objectify.fromstring(test_data)
root = Grp.group
gName = GetThis(root, "name", "No Name")
err_tst = GetThis(root, "not-there", "Error OK")
p_count = root.pool_count if hasattr(root, 'pool_count') else (-1)
实际上，我收到以下错误:
Traceback (most recent call last):
File "C:/Mirc/Python/Temp Files/test_lxml.py", line 108, in <module>
gName = GetThis(root, "name", "")
File "C:/Mirc/Python/Temp Files/test_lxml.py", line 10, in GetThis
print (el.attr)
File "lxml.objectify.pyx", line 218, in lxml.objectify.ObjectifiedElement.__getattr__ (src\lxml\lxml.objectify.c:3506)
File "lxml.objectify.pyx", line 437, in lxml.objectify._lookupChildOrRaise (src\lxml\lxml.objectify.c:5756)
AttributeError: no such child: attr
谢谢!
请您参考如下方法:
不需要您的 GetThis 函数，因为您可以简单地使用 getattr :
gName = getattr(root, "name", "No Name")
err_tst = getattr(root, "not-there", "Error OK")
第一个参数是对象，第二个是属性，第三个是可选的，是在属性不存在时返回的默认值(如果省略最后一部分，将返回一个 AttributeError 被提升)。
上面两行代码等价于:
gName = root.name if hasattr(root, "name") else "No Name"
err_tst = root.not-there if hasattr(root, "not-there") else "Error OK"
