How to validate an xml with repeating child elements

Question

I have an xml document with three child elements repeating in any order. I had xsd:sequence element in the xsd because of which the xml doesn't get validated. I can not use xsd:all because the elements occur more than once.

Kindly help me on this.

Here is the xml

 <Trailer>      
        <TrailerField name="SegmentLabelOne" length="4" type="String">TSTS</TrailerField>
        <TrailerField name="SegmentLabelTwo" length="2" type="String">00</TrailerField>
       <CountItem length="10" type="Numeric">MT</CountItem> 
        <TrailerField name="SegmentLabelThree" length="2" type="String">01</TrailerField>
        <CountItem length="10" type="Numeric">MA</CountItem>
        <TrailerField name="SegmentLabelFour" length="2" type="String">02</TrailerField>
        <TrailerField name="FilerOne" length="65" type="String">                                                                 </TrailerField>
 </Trailer>

And here is the xsd

<xsd:complexType name="TrailerSegment">
<xsd:sequence>
            <xsd:element name="NameOfElement" minOccurs="0" maxOccurs="unbounded">
                <xsd:complexType>
                    <xsd:simpleContent>  
                        <xsd:extension base="xsd:string">  
                            <xsd:attribute name="name" type="xsd:string"></xsd:attribute>
                        </xsd:extension>
                    </xsd:simpleContent>
                </xsd:complexType>
            </xsd:element>
            <xsd:element name="CountItem" minOccurs="0" maxOccurs="unbounded">
                <xsd:complexType>
                    <xsd:simpleContent>  
                        <xsd:extension base="xsd:string">
                            <xsd:attribute name="length" type="xsd:string"></xsd:attribute>
                            <xsd:attribute name="type" type="xsd:string"></xsd:attribute>
                        </xsd:extension>
                    </xsd:simpleContent>
                </xsd:complexType>
            </xsd:element>
            <xsd:element name="TrailerField" minOccurs="0" maxOccurs="unbounded">
                <xsd:complexType>
                    <xsd:simpleContent>  
                        <xsd:extension base="xsd:string">  
                            <xsd:attribute name="name" type="xsd:string"></xsd:attribute>
                            <xsd:attribute name="length" type="xsd:string"></xsd:attribute>
                            <xsd:attribute name="type" type="xsd:string"></xsd:attribute>
                        </xsd:extension>
                    </xsd:simpleContent>
                </xsd:complexType>
            </xsd:element>
</xsd:sequence>
</xsd:complexType>

Answer 1

You need something like this:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="Trailer">
    <xs:complexType>
      <xs:sequence>
        <xs:choice maxOccurs="unbounded">
          <xs:element name="TrailerField">
            <xs:complexType>
              <xs:simpleContent>
                <xs:extension base="xs:string">
                  <xs:attribute name="name" type="xs:string" use="required" />
                  <xs:attribute name="length" type="xs:unsignedByte" use="required" />
                  <xs:attribute name="type" type="xs:string" use="required" />
                </xs:extension>
              </xs:simpleContent>
            </xs:complexType>
          </xs:element>
          <xs:element name="CountItem">
            <xs:complexType>
              <xs:simpleContent>
                <xs:extension base="xs:string">
                  <xs:attribute name="length" type="xs:unsignedByte" use="required" />
                  <xs:attribute name="type" type="xs:string" use="required" />
                </xs:extension>
              </xs:simpleContent>
            </xs:complexType>
          </xs:element>
        </xs:choice>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

The <xs:choice> gives you the choice of any one of the elements inside the choice, and since the <xs:choice> has an attribute of maxOccurs=unbounded , you can have any number of repetitions therefore --> you get to choose any number of those elements included, in any order.