Key/keyref not performed on dynamic types

[robbert-harms]

Hi brunato,

I was trying to add a key/keyref to one of my nodes with a dynamic type, but unfortunately it won't catch incorrect values. I made a small demo case:

XSD:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning" elementFormDefault="qualified"
    attributeFormDefault="unqualified" vc:minVersion="1.1"
    targetNamespace="http://www.test.com/XMLSchema/data/2021"
    xmlns="http://www.test.com/XMLSchema/data/2021"
    xmlns:ad="http://www.test.com/XMLSchema/data/2021">
    <xs:element name="assessment">
        <xs:annotation>
            <xs:documentation>Data about the performed tests.</xs:documentation>
        </xs:annotation>
        <xs:complexType>
            <xs:sequence>
                <xs:element maxOccurs="unbounded" minOccurs="0" name="part" type="AssessmentPart">
                    <xs:key name="circle_id_key">
                        <xs:annotation>
                            <xs:documentation>For ContrastVisionTest. 

Since all parts are types we can not add keys and keyrefs to them. As such, we add the constraints here.</xs:documentation>
                        </xs:annotation>
                        <xs:selector xpath="ad:screen_elements/ad:contrast_circles/ad:circle"/>
                        <xs:field xpath="@circle_id"/>
                    </xs:key>
                    <xs:keyref name="circle_id_keyref" refer="circle_id_key">
                        <xs:selector xpath="ad:events/ad:circle_pressed"/>
                        <xs:field xpath="@circle_id"/>
                    </xs:keyref>
                </xs:element>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
    <xs:complexType abstract="true" name="AssessmentPart">
        <xs:annotation>
            <xs:documentation>Base type for the assessment element.</xs:documentation>
        </xs:annotation>
    </xs:complexType>
    <xs:complexType abstract="true" name="AssessmentTest">
        <xs:annotation>
            <xs:documentation>Base type for a test.</xs:documentation>
        </xs:annotation>
        <xs:complexContent>
            <xs:extension base="AssessmentPart"/>
        </xs:complexContent>
    </xs:complexType>
    <xs:complexType name="ContrastVisionTest">
        <xs:complexContent>
            <xs:extension base="AssessmentTest">
                <xs:sequence>
                    <xs:element name="screen_elements">
                        <xs:complexType>
                            <xs:sequence>
                                <xs:element name="contrast_circles">
                                    <xs:complexType>
                                        <xs:sequence>
                                            <xs:element maxOccurs="3" name="circle" minOccurs="3">
                                                <xs:complexType>
                                                  <xs:attribute name="circle_id" use="required">
                                                  <xs:annotation>
                                                  <xs:documentation>The id of this circle, used to reference the circle presses.</xs:documentation>
                                                  </xs:annotation>
                                                  <xs:simpleType>
                                                  <xs:restriction base="xs:integer">
                                                  <xs:minInclusive value="0"/>
                                                  <xs:maxInclusive value="9"/>
                                                  </xs:restriction>
                                                  </xs:simpleType>
                                                  </xs:attribute>
                                                </xs:complexType>
                                            </xs:element>
                                        </xs:sequence>
                                    </xs:complexType>
                                </xs:element>
                            </xs:sequence>
                        </xs:complexType>
                    </xs:element>
                    <xs:element name="events">
                        <xs:complexType>
                            <xs:sequence>
                                <xs:element maxOccurs="unbounded" minOccurs="0"
                                    name="circle_pressed">
                                    <xs:complexType>
                                        <xs:attribute name="circle_id" type="xs:integer"
                                            use="required"/>
                                    </xs:complexType>
                                </xs:element>
                            </xs:sequence>
                        </xs:complexType>
                    </xs:element>
                </xs:sequence>
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>
</xs:schema>

XML:

<?xml version="1.0" encoding="UTF-8"?>
<assessment xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning"
 xmlns="http://www.test.com/XMLSchema/data/2021"
 xsi:schemaLocation="http://www.test.com/XMLSchema/data/2021">
    <part xsi:type="ContrastVisionTest">
        <screen_elements>
            <contrast_circles>
                <circle circle_id="1"/>
                <circle circle_id="1"/>
                <circle circle_id="2"/>
            </contrast_circles>
        </screen_elements>
        <events>
            <circle_pressed circle_id="0"/>
            <circle_pressed circle_id="1"/>
            <circle_pressed circle_id="2"/>
        </events>
    </part>
</assessment>

Other validation libraries, such as Xerex throw a warning that circle_id is not unique, i.e. that I use circle_id="1" twice.

The XMLSchema library in general works for validating key/keyref, but it seems to fail with elements referencing an xsi:type, such as in the above example.

Is this something that can be fixed?

Thank you for making this library, it helps me a lot in moving fully to Python.

Best,

Robbert

[brunato]

Hi,
each key identity has a dictionary with schema's elements related to its XPath selector, so the fix is to add the missing XSD elements when a dynamic type is used. For doing this I've added a dummy element for XPath operations and a part inside the "xsi:type" block of XsdElement.iter_decode().

        if XSI_TYPE in elem.attrib:
            type_name = elem.attrib[XSI_TYPE].strip()
            try:
                xsd_type = self.maps.get_instance_type(type_name, xsd_type, namespaces)
            except (KeyError, TypeError) as err:
                yield self.validation_error(validation, err, elem, **kwargs)
            else:
                # Add missing selected elements to identity
                if self.identities:
                    xpath_element = XPathElement(self.name, xsd_type)
                    for identity in self.identities.values():
                        context = IdentityXPathContext(self.schema, item=xpath_element)
                        for e in identity.selector.token.select_results(context):
                            if e not in identity.elements:
                                identity.elements[e] = None

The fix will be available in the next release.

Thank you for providing clear samples for the case (I will add them into package's tests).

[robbert-harms]

Hi Brunato,

Thank you for your looking into the matter. Glad my examples are of help.

Looking forward to the next release.

Best wishes,

Robbert

[brunato]

Hi @robbert-harms,
a new release of xmlschema is available (v1.6.2). If you upgrade also elementpath is updated to the latest (for fixing issue #243).

Best regards,
Davide

[robbert-harms]

Thank you Davide, for repairing this so swiftly.

Your fixed for this worked as well.