What is Attributes in XML
This topic fully describe about XML Attributes. After learn this you are able to understand how we can use XML Attributes.
DTD Attributes in xml
Attributes in xml declared with the ATTLIST declaration. with a different element that has the different work
For Example :
<!ATTLIST element-name attribute-name attribute-type default-value>
example:
<!ATTLIST payment CDATA "check">
XML example:
<payment ="check" />
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Note: Attributes can be several type
Attribute Type |
Attributes Description |
CDDATA |
The value is character data |
ID |
The value is unique id |
IDRef |
The value in the id of other element |
IDREFS |
The value in the id of list of other ids |
NMTOKEN |
The value is a valid xml name |
XML: |
The value is the predefine or default xml value |
Entities |
The values is the list of entitles |
The default value can be also . These are following
Value |
description |
value |
default value of the attributes |
#REQUIRED |
The value must be required |
#IMPLIED |
The Attribute is not required |
#FIXED value |
Attribute value fixed |
Default Attribute value
DTD:
<!ELEMENT square EMPTY>
<!ATTLIST height width CDATA "0">
Valid XML:
<square height="200" />
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#REQUIRED
<!ATTLIST element-name attribute-name attribute-type #REQUIRED>
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Note : - this is the declaration of #REQUIRED
Example:
DTD:
<!ATTLIST personal number CDATA #REQUIRED>
Valid XML:
<personal number="677" />
Invalid XML:
<personal/>
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#IMPLIED
<!ATTLIST element-name attribute-name attribute-type #IMPLIED>
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Note : this is only declaration part of #IMPLIED
Example:
DTD:
<!ATTLIST fax no CDATA #IMPLIED>
Valid XML:
<fax no="555-9995588" />
Valid XML:
<fax />
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#FIXED value
<!ATTLIST element-name attribute-name attribute-type #FIXED "value">
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Note: This is only the declaration portion of the #FIXED value
Example :
DTD:
<!ATTLIST company CDATA #FIXED "MCN Private solution">
Valid XML:
< company="MCN private solution" />
Invalid XML:
< company="dotnet factor" />
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Enumerated Attribute Values
How to declared it
<!ATTLIST element-name attribute-name (en1|en2|..) default-value>
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Example :
DTD:
<!ATTLIST pay type (check|cash) "cash">
XML example:
<pay type="check" />
or
<pay type="cash" />
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Enumerated attributes value must be one of the legal value ( check or cash).
further Readings
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