Frequently Asked Questions

Why are all properties marked as optional?

We rely on the fields ordering for all binding procedures and due to the following limitation we have to mark even required fields as optional.

TypeError will be raised if a field without a default value follows a field with a default value. This is true whether this occurs in a single class, or as a result of class inheritance.

Source: dataclasses

In Python 3.10 dataclasses introduced a new directive kw_only that resolves the above limitation and xsdata handling. Read more

If you can’t update just yet please check the attrs plugin!

Why are elements out of order?

There are a few cases when elements can appear in any order. The default simplified models don’t have a way to store the original order of the elements in a document.

Repeatable choice elements is one of them.

<xsd:schema xmlns:xsd="">
  <xsd:element name="root">
      <xsd:choice maxOccurs="unbounded">
        <xsd:element ref="alpha" />
        <xsd:element ref="bravo" />

In order to maintain the original order between roundtrip conversions you need to enable compound fields. Compound fields are group fields and can be used to wrap mixed context elements, repeatable choice elements or complex sequential elements.

Read more