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Thread: [xsd] restricting complex type

  1. #1
    Join Date
    Jan 2009
    Posts
    3

    [xsd] restricting complex type

    hi all. i'm a newbie in xsd world. my question regards the complex type.

    let's suppose that we have this definition:
    Code:
    <xs:complexType name = "employee">
      <xs:sequence>
         <xs:element name="name" type="xs:string"/>
         <xs:element name="surname" type="xs:string"/>
         <xs:element name="nation" type="xs:string"/>
      </xs:sequence>
    </xs:complexType>
    well now i'll restrict this complex type creating a new one "itaemployee", which contains a fixed value for the tag "nation" (=italy)

    Code:
    <xs:complexType name = "itaemployee">
      <xs:complexContent>
        <xs:restriction base = "employee">
         <xs:sequence>
          <xs:element name="name" type="xs:string"/>
          <xs:element name="surname" type="xs:string"/>
          <xs:element name="nation" type="xs:string" fixed="italy"/>
         </xs:sequence>
        </xs:restriction>
       <xs:complexContent>
    <xs:complexType>
    now, my question: why i should restrict the type employee to have itaemployee? I could also write:

    Code:
    <xs:complexType name = "itaemployee">
         <xs:sequence>
          <xs:element name="name" type="xs:string"/>
          <xs:element name="surname" type="xs:string"/>
          <xs:element name="nation" type="xs:string" fixed="italy"/>
         </xs:sequence>
    <xs:complexType>
    having a type called itaemployee...
    what is the benefit using the restriction of the complex type?

    help me to understand, please!

  2. #2
    Join Date
    May 2008
    Posts
    381
    The benefit in your example is rather questionable. However, when you have a number of elements that are in a category of sorts, such as when you buy something at a store, including employee discounts:
    Code:
    <xs:complexType name="item.type">
      <xs:sequence>
        <xs:element name="name" type="xs:string"/>
        <xs:element name="price" type="xs:decimal"/>
        <xs:element name="discount" type="xs:decimal" minOccurs="0"
                    default="0.0"/>
        <xs:element name="employee-discount" type="xs:decimal" minOccurs="0"
                    default="0.0"/>
      </xs:sequence>
    </xs:complexType>
    Code:
    <xs:complexType name="employee-item.type">
      <xs:complexContent>
        <xs:restriction base="item.type">
          <xs:sequence>
            <xs:element name="name" type="xs:string"/>
            <xs:element name="price" type="xs:decimal"/>
            <xs:element name="discount" type="xs:decimal" minOccurs="0"
                        default="0.0"/>
            <xs:element name="employee-discount" type="xs:decimal"
                        fixed="0.15"/>
          </xs:sequence>
        </xs:restriction>
      </xs:complexContent>
    </xs:complexType>
    Then instead of using the following:
    Code:
    <item>
      <name>Example</name>
      <price>9.99</price>
    </item>
    
    <item>
      <name>Example</name>
      <price>9.99</price>
      <employee-discount>0.15</employee-discount>
    </item>
    You could use this instead:
    Code:
    <item>
      <name>Example</name>
      <price>9.99</price>
    </item>
    
    <employee-item>
      <name>Example</name>
      <price>9.99</price>
    </employee-item>
    Again, a dumb example, but when you consider adding more elements (e.g. instead of "price", you have "price" and "profit"), you might find it useful. Honestly, I don't typically see using restrictions in this way beneficial. Extensions are more useful for this sort of thing...adding elements and groups rather than restricting elements. I don't find much use for restrictions in complex content. Enumerations in simple content and simple types are what I use them for most commonly.

  3. #3
    Join Date
    Jan 2009
    Posts
    3
    yes, i see...
    but I would have been able to write like this:

    Code:
    <xs:complexType name="employee-item.type">
          <xs:sequence>
            <xs:element name="name" type="xs:string"/>
            <xs:element name="price" type="xs:decimal"/>
            <xs:element name="discount" type="xs:decimal" minOccurs="0"
                        default="0.0"/>
            <xs:element name="employee-discount" type="xs:decimal"
                        fixed="0.15"/>
      </xs:complexContent>
    </xs:complexType>
    id est: defining a new complex type called "employee-item.type"...the usage is the same, but exists the restriction of complex type...so my question is: what is the benefit of this restriction? i was thinking, maybe exists an object-oriented benefit that i cannot see in this moment...

    help help
    Last edited by np2k; 01-25-2009 at 09:55 AM.

  4. #4
    Join Date
    Jan 2009
    Posts
    3
    can someone help me?

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