XSD validation error. "A Problem Was Found Starting At: Attribute"

Question

I am validating my XSD through https://www.freeformatter.com/xml-validator-xsd.html but it throws an error

The content of sequence must match (annotation?, (element | Group | Choice | Sequence | Any)*). A problem was found starting at: Attribute

I need to make NOT NULL for the reportType. I used attribute (use="required") and tried to move the attribute out of sequence as well but it still throws an error. Any help will be appreciated.

Below is my XSD code.

<?xml version="1.0"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="missing">

  <xs:complexType>
    <xs:sequence>
      <xs:element name="missingID" type="xs:string"/>
      <xs:attribute name="reportType" use="required"/>
      <xs:simpleType>
        <xs:restriction base="xs:string">
          <xs:minLength value= "1"/>
          <xs:maxLength value= "255"/>
        </xs:restriction>
      </xs:simpleType>

      <xs:element name="reportDescription">
        <xs:simpleType >
          <xs:restriction base="xs:string">
            <xs:minLength value= "1"/>
            <xs:maxLength value= "255"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:element>

      <xs:element name="contact">
        <xs:simpleType >
          <xs:restriction base="xs:string">
            <xs:minLength value= "1"/>
            <xs:maxLength value= "255"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:element>

      <xs:element name="reward">
        <xs:simpleType >
          <xs:restriction base="xs:string">
            <xs:minLength value= "1"/>
            <xs:maxLength value= "255"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:element>

      <xs:element name="location">
        <xs:simpleType >
          <xs:restriction base="xs:string">
            <xs:minLength value= "1"/>
            <xs:maxLength value= "255"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:element>

      <xs:element name="photo" type="xs:base64Binary"/>
      <xs:element name="statusID" type="xs:string"/>
      <xs:element name="userID" type="xs:string"/>

      <xs:element name="created_date">
        <xs:simpleType>
          <xs:restriction base="xs:dateTime"/>
        </xs:simpleType>
      </xs:element>

    </xs:sequence>

  </xs:complexType>

</xs:element>
</xs:schema>

(Added from a subsequent comment:)

This is the xml I'm working with my xsd.

<?xml version="1.0" encoding="UTF-8"?> 
<missing> 
  <missingID> m1234 </missingID> 
  <reportType> Missing Report </reportType> 
  <reportDescription> A person was missing yesterday at Manhattan around 8 P.M. </reportDescription> 
  <contact> 1234567891 </contact> 
  <reward> Cash $10000 </reward> 
  <location> New York </location> 
  <photo> </photo>  
  <statusID> s1234 </statusID> 
  <userID> a1234 </userID> 
  <created_date> 2019-11-29T09:00:15 </created_date> 
</missing>

Answer 1

The immediate problem causing your immediate error is that the reportType attribute declaration has to follow the xs:sequence, not be within it. See How to add attribute declaration in XSD for element with sequence of child elements?

You'll also have to move the xs:simpleType that appears to be intended to be associated with the reportType attribute to within that attributes declaration rather than following it.

Altogether, here's is your (now valid) XSD with the above repairs:

<?xml version="1.0"?>
<xs:schema attributeFormDefault="unqualified" 
           elementFormDefault="qualified"
           xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="missing">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="missingID" type="xs:string"/>
        <xs:element name="reportDescription">
          <xs:simpleType >
            <xs:restriction base="xs:string">
              <xs:minLength value= "1"/>
              <xs:maxLength value= "255"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:element>
        <xs:element name="contact">
          <xs:simpleType >
            <xs:restriction base="xs:string">
              <xs:minLength value= "1"/>
              <xs:maxLength value= "255"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:element>
        <xs:element name="reward">
          <xs:simpleType >
            <xs:restriction base="xs:string">
              <xs:minLength value= "1"/>
              <xs:maxLength value= "255"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:element>
        <xs:element name="location">
          <xs:simpleType >
            <xs:restriction base="xs:string">
              <xs:minLength value= "1"/>
              <xs:maxLength value= "255"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:element>
        <xs:element name="photo" type="xs:base64Binary"/>
        <xs:element name="statusID" type="xs:string"/>
        <xs:element name="userID" type="xs:string"/>
        <xs:element name="created_date">
          <xs:simpleType>
            <xs:restriction base="xs:dateTime"/>
          </xs:simpleType>
        </xs:element>
      </xs:sequence>
      <xs:attribute name="reportType" use="required">
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:minLength value= "1"/>
            <xs:maxLength value= "255"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
</xs:schema>

Answer 2

My first thought was that you're trying to define a complex type with simple content. If that's the case then it's easy to find examples and tutorials, see for example here:

XML Schema: Element with attributes containing only text?

But when I looked again, I'm not sure I know what you are trying to do. The problem is, you haven't shown us the XML that you want to validate. It's hard to tell you what's wrong with incorrect code when you don't know what it's supposed to do.