无法绑定到具有嵌套（匿名）类型的 pyxb 类

Question

我遵循了来自this thread 的说明以及来自此 XML 的说明：

<?xml version="1.0" encoding="UTF-8" ?>
<my_report>    
<something>
<foo>
Yes
</foo>
</something>

<something_else>
<id>4</id>
<foo>Finally</foo>
<score>0.2</score>
</something_else>    
</my_report>

我使用 this tool online 创建了以下 XSD 架构。

<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="my_report">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="something">
          <xs:complexType>
            <xs:sequence>
              <xs:element type="xs:string" name="foo"/>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="something_else">
          <xs:complexType>
            <xs:sequence>
              <xs:element type="xs:byte" name="id"/>
              <xs:element type="xs:string" name="foo"/>
              <xs:element type="xs:float" name="score"/>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

然后我在shell中调用pyxben -u my_schema.csd -m my_schema，然后尝试使用绑定构建对象：

from my_schema import my_report
my_xml_report = my_report()

到目前为止，这似乎有效（我可以访问my_xml_report.something）。但是，当我尝试填充嵌套元素时：

my_xml_report.something.foo = "No"

我收到错误'NoneType'object has no atttribute 'foo'。

The documentation 谈论anonymous types 似乎与我的问题有关，但我仍然无法让它工作：

import pyxb
my_xml_report.something = pyxb.BIND('foo', "No")

我收到错误MixedContentError: invalid non-element content

我该如何填写这个 XML？

Answer 1

非规范化架构很困难，您可能需要尝试多种方法来提供所需的信息。这是一个带注释的示例，虽然我使用的是 PyXB 1.2.3，所以功能可能更完整：

import pyxb
import my_schema

rep = my_schema.my_report()

# The something element here is very simple, with a single string
# element.  For the inner string element foo PyXB can figure things
# out for itself.  For the outer element it needs help.
#
# In a normalized schema where the type of something was tSomething,
# you would do:
#
#   rep.something = tSomething('yes')
#
# Without a tSomething easily reachable, to build it up piece-by-piece
# you could do:
rep.something = pyxb.BIND()  # Create an instance of whatever type satisfies something
rep.something.foo = 'yes'    # Assign to the foo element of what got created

# You can then optimize.  Here pyxb.BIND substitutes for the something
# element wrapper around that string, and figures out for itself that
# the "yes" can only go in the foo element:
rep.something = pyxb.BIND('yes')

# In fact, sometimes PyXB can even figure out the intermediate
# intermediate layers:
rep.something = 'yes'
# No more than two of them, though (and the lowest must be a simple type).

# Similarly here pyxb.BIND substitutes for the type of the
# something_else element.  Again the inner content is unambiguous and
# sequential, so the values can be provided in the constructor.
rep.something_else = pyxb.BIND(4, 'finally', 0.2)

print rep.toxml('utf-8')