UniqueFieldValueConstraint SourceCode GPL - https://github.com/iboxdb/db4o-gpl

java.lang.Object
- com.db4o.constraints.UniqueFieldValueConstraint

All Implemented Interfaces:

ConfigurationItem
```
public class UniqueFieldValueConstraint
extends java.lang.Object
implements ConfigurationItem
```
Configures a field of a class to allow unique values only. In C/S mode, add this configuration-item to the server side only. You need to turn on indexing for the given field, otherwise the unique constrain won't work. Add this to your configuration with CommonConfiguration.add(com.db4o.config.ConfigurationItem)

Field Summary

Fields
Modifier and Type Field Description

protected java.lang.Object _clazz

protected java.lang.String _fieldName

Constructor Summary

Constructors
Constructor	Description
`UniqueFieldValueConstraint(java.lang.Object clazz, java.lang.String fieldName)`	constructor to create a UniqueFieldValueConstraint.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`apply(InternalObjectContainer objectContainer)`	internal method, public for implementation reasons.
`void`	`prepare(Configuration configuration)`	Gives a chance for the item to augment the configuration.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - _clazz
```
protected final java.lang.Object _clazz
```
  - _fieldName
```
protected final java.lang.String _fieldName
```
- Constructor Detail
  - UniqueFieldValueConstraint
```
public UniqueFieldValueConstraint(java.lang.Object clazz,
                                  java.lang.String fieldName)
```
    constructor to create a UniqueFieldValueConstraint.
    
    Parameters:
    
    clazz - can be a class (Java) / Type (.NET) / instance of the class / fully qualified class name
    
    fieldName - the name of the field that is to be unique.
- Method Detail
  - prepare
```
public void prepare(Configuration configuration)
```
    Description copied from interface: ConfigurationItem
    
    Gives a chance for the item to augment the configuration.
    
    Specified by:
    
    prepare in interface ConfigurationItem
    
    Parameters:
    
    configuration - the configuration that the item was added to
  - apply
```
public void apply(InternalObjectContainer objectContainer)
```
    internal method, public for implementation reasons.
    
    Specified by:
    
    apply in interface ConfigurationItem
    
    Parameters:
    
    objectContainer - the ObjectContainer to configure