data-member-order.md

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Data Member Order		03/30/2017	.net-framework			dotnet-clr		article	data contracts [WCF], ordering members	0658a47d-b6e5-4ae0-ba72-ababc3c6ff33	17	Erikre	erikre	erikre

Data Member Order

In some applications, it is useful to know the order in which data from the various data members is sent or is expected to be received (such as the order in which data appears in the serialized XML). Sometimes it may be necessary to change this order. This topic explains the ordering rules.

Basic Rules

The basic rules for data ordering include:

• If a data contract type is a part of an inheritance hierarchy, data members of its base types are always first in the order.

• Next in order are the current type’s data members that do not have the xref:System.Runtime.Serialization.DataMemberAttribute.Order%2A property of the xref:System.Runtime.Serialization.DataMemberAttribute attribute set, in alphabetical order.

• Next are any data members that have the xref:System.Runtime.Serialization.DataMemberAttribute.Order%2A property of the xref:System.Runtime.Serialization.DataMemberAttribute attribute set. These are ordered by the value of the Order property first and then alphabetically if there is more than one member of a certain Order value. Order values may be skipped.

Alphabetical order is established by calling the xref:System.String.CompareOrdinal%2A method.

Examples

Consider the following code.

[!code-csharpC_DataContractNames#4] [!code-vbC_DataContractNames#4]

The XML produced is similar to the following.

<DerivedType>  
    <!-- Zebra is a base data member, and appears first. -->  
    <zebra/>   
  
    <!-- Cat has no Order, appears alphabetically first. -->  
    <cat/>  
  
   <!-- Dog has no Order, appears alphabetically last. -->  
    <dog/>   
  
    <!-- Bird is the member with the smallest Order value -->  
    <bird/>  
  
    <!-- Albatross has the next Order value, alphabetically first. -->  
    <albatross/>  
  
    <!-- Parrot, with the next Order value, alphabetically last. -->  
     <parrot/>  
  
    <!-- Antelope is the member with the highest Order value. Note that   
    Order=2 is skipped -->  
     <antelope/>   
</DerivedType>  

See Also

xref:System.Runtime.Serialization.DataContractAttribute
Data Contract Equivalence
Using Data Contracts