content/api/user-guide/6.5-ava.mdtext

Title: 6.5 - Ava
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# 6.5 - Ava

An _Ava_ is used to store an _Attribute_ value associated to an _AttributeType_. 

It describes a container holding an _AttributeType_ associated with a _Value_ in a _Rdn_. An example would be:

    :::Java
    dc=example

where 'dc' is the _AttributeType_ and 'example' its associated value.

The value can be a binary or a String value, depending on the _AttributeType_.

We can create a schema aware _Ava_, or just a plain _Ava_. Having a schema aware _Ava_ allows further controls to be made on the value we inject.  Is syntax will be checked against the _AttributeType_ syntax.

Most of the time, one will not need to create or manipulate an _Ava_, as it's an internal element of a _Rdn_.

_Ava_ is also a _Externalizable_ class.

_Ava_ instances are immutable.


## Usage

As for the _Dn_ and _Rdn_ classes, we have to hold two representations of its internal _AttributeType_ and _Value_.  The User Provided form, and the escaped form (which are used inside filters). If the _AVA_ is schema aware, the escaped form will be computed, otherwise we store the user provided form. Let's see some examples.


### Schema Aware Ava

Here we will create an _AVA_ and check that the user provided values are preserved. The _getName()_ and _getString()_ methods will give back this user provided form, in a form that allows it to be used in a Filter.

    :::Java
    Ava atav = new Ava( schemaManager, " CommonName ", " This is    a TEST " );
    System.out.println( "toString     : '" + atav.toString() + "'" );
    System.out.println( "Escaped      : '" + atav.getEscaped() + "'" );
    System.out.println( "UserProvided : '" + atav.getName() + "'" );

will produce :

    :::Java
    toString     : ' CommonName =\ This is    a TEST\ '
    Escaped      : ' CommonName =\ This is    a TEST\ '
    UserProvided : ' CommonName =\ This is    a TEST\ '


*{+}Not Schema Aware{+}*

The biggest difference in this case is that the _AttributeType_ will not be replaced by its _Oid_, but instead by a lowercase form of the provided ID. We also escape the leading and trailing spaces in the value.

{code}
public void testAvaSimpleNorm() throws LdapException
{
    Ava atav = new Ava( null, " CommonName ", " This is    a TEST " );
    assertEquals( " CommonName = This is    a TEST ", atav.toString() );
    assertEquals( "commonname=\\ This is    a TEST\\ ", atav.getNormName() );
    assertEquals( " CommonName = This is    a TEST ", atav.getUpName() );
}
{code}